Academic literature on the topic 'Floral meristem'
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Journal articles on the topic "Floral meristem"
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Laudencia-Chingcuanco, Debbie, and Sarah Hake. "The indeterminate floral apex1 gene regulates meristem determinacy and identity in the maize inflorescence." Development 129, no. 11 (June 1, 2002): 2629–38. http://dx.doi.org/10.1242/dev.129.11.2629.
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Meristems may be determinate or indeterminate. In maize, the indeterminate inflorescence meristem produces three types of determinate meristems: spikelet pair, spikelet and floral meristems. These meristems are defined by their position and their products. We have discovered a gene in maize, indeterminate floral apex1 (ifa1) that regulates meristem determinacy. The defect found in ifa1 mutants is specific to meristems and does not affect lateral organs. In ifa1 mutants, the determinate meristems become less determinate. The spikelet pair meristem initiates more than a pair of spikelets and the spikelet meristem initiates more than the normal two flowers. The floral meristem initiates all organs correctly, but the ovule primordium, the terminal product of the floral meristem, enlarges and proliferates, expressing both meristem and ovule marker genes. A role for ifa1 in meristem identity in addition to meristem determinacy was revealed by double mutant analysis. In zea agamous1 (zag1) ifa1 double mutants, the female floral meristem converts to a branch meristem whereas the male floral meristem converts to a spikelet meristem. In indeterminate spikelet1 (ids1) ifa1 double mutants, female spikelet meristems convert to branch meristems and male spikelet meristems convert to spikelet pair meristems. The double mutant phenotypes suggest that the specification of meristems in the maize inflorescence involves distinct steps in an integrated process.
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Kong, Doudou, and Annette Becker. "Then There Were Plenty-Ring Meristems Giving Rise to Many Stamen Whorls." Plants 10, no. 6 (June 3, 2021): 1140. http://dx.doi.org/10.3390/plants10061140.
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Floral meristems are dynamic systems that generate floral organ primordia at their flanks and, in most species, terminate while giving rise to the gynoecium primordia. However, we find species with floral meristems that generate additional ring meristems repeatedly throughout angiosperm history. Ring meristems produce only stamen primordia, resulting in polystemous flowers (having stamen numbers more than double that of petals or sepals), and act independently of the floral meristem activity. Most of our knowledge on floral meristem regulation is derived from molecular genetic studies of Arabidopsis thaliana, a species with a fixed number of floral organs and, as such of only limited value for understanding ring meristem function, regulation, and ecological value. This review provides an overview of the main molecular players regulating floral meristem activity in A. thaliana and summarizes our knowledge of ring primordia morphology and occurrence in dicots. Our work provides a first step toward understanding the significance and molecular genetics of ring meristem regulation and evolution.
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Fletcher, J. C. "The ULTRAPETALA gene controls shoot and floral meristem size in Arabidopsis." Development 128, no. 8 (April 15, 2001): 1323–33. http://dx.doi.org/10.1242/dev.128.8.1323.
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The regulation of proper shoot and floral meristem size during plant development is mediated by a complex interaction of stem cell promoting and restricting factors. The phenotypic effects of mutations in the ULTRAPETALA gene, which is required to control shoot and floral meristem cell accumulation in Arabidopsis thaliana, are described. ultrapetala flowers contain more floral organs and whorls than wild-type plants, phenotypes that correlate with an increase in floral meristem size preceding organ initiation. ultrapetala plants also produce more floral meristems than wild-type plants, correlating with an increase in inflorescence meristem size without visible fasciation. Expression analysis indicates that ULTRAPETALA controls meristem cell accumulation partly by limiting the domain of CLAVATA1 expression. Genetic studies show that ULTRAPETALA acts independently of ERA1, but has overlapping functions with PERIANTHIA and the CLAVATA signal transduction pathway in controlling shoot and floral meristem size and meristem determinacy. Thus ULTRAPETALA defines a novel locus that restricts meristem cell accumulation in Arabidopsis shoot and floral meristems.
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Souer, E., A. van der Krol, D. Kloos, C. Spelt, M. Bliek, J. Mol, and R. Koes. "Genetic control of branching pattern and floral identity during Petunia inflorescence development." Development 125, no. 4 (February 15, 1998): 733–42. http://dx.doi.org/10.1242/dev.125.4.733.
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A main determinant of inflorescence architecture is the site where floral meristems are initiated. We show that in wild-type Petunia bifurcation of the inflorescence meristem yields two meristems of approximately equal size. One terminates into a floral meristem and the other maintains its inflorescence identity. By random transposon mutagenesis we have generated two mutants in which the architecture of the inflorescence is altered. In the extra petals- (exp) mutant the inflorescence terminates with the formation of a single terminal flower. Phenotypic analysis showed that exp is required for the bifurcation of inflorescence meristems. In contrast, the aberrant leaf and flower- (alf) mutant is affected in the specification of floral meristem identity while the branching pattern of the inflorescence remains unaltered. A weak alf allele was identified that, after bifurcation of the inflorescence meristem, yields a ‘floral’ meristem with partial inflorescence characteristics. By analysing independent transposon dTph1 insertion alleles we show that the alf locus encodes the Petunia FLORICAULA/LEAFY homolog. In situ hybridisation shows that alf is expressed in the floral meristem and also in the vegetative meristem. Differences and similarities between these Petunia mutants and mutations affecting inflorescence architecture in other species will be discussed.
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Grbić, Vojislava. "Comparative analysis of axillary and floral meristem development." Canadian Journal of Botany 83, no. 4 (April 1, 2005): 343–49. http://dx.doi.org/10.1139/b05-017.
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Axillary and floral meristems are shoot meristems that initiate postembryonically. In Arabidopsis, axillary meristems give rise to branches during vegetative development while floral meristems give rise to flowers during reproductive development. This review compares the development of these meristems from their initiation at the shoot apical meristem up to the establishment of their specific developmental fates. Axillary and floral meristems originate from lateral primordia that form at flanks of the shoot apical meristem. Initial development of vegetative and reproductive primordia are similar, resulting in the formation of a morphologically defined primordium partitioned into adaxial and abaxial domains. The adaxial primordial domain is competent to form a meristem, while the abaxial domain correlates with the formation of a leaf. This review proposes that all primordia partition into domains competent to form the meristem and the leaf. According to this model, a vegetative primordium develops as leaf-bias while a reproductive primordium develops as meristem-bias.Key words: SHOOTMERISTEMLESS, LATERAL SUPPRESSOR, AINTEGUMENTA, adaxial primordial domain, abaxial primordial domain, shoot morphogenesis.
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Thiel, J., R. Koppolu, C. Trautewig, C. Hertig, S. M. Kale, S. Erbe, M. Mascher, et al. "Transcriptional landscapes of floral meristems in barley." Science Advances 7, no. 18 (April 2021): eabf0832. http://dx.doi.org/10.1126/sciadv.abf0832.
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Organ development in plants predominantly occurs postembryonically through combinatorial activity of meristems; therefore, meristem and organ fate are intimately connected. Inflorescence morphogenesis in grasses (Poaceae) is complex and relies on a specialized floral meristem, called spikelet meristem, that gives rise to all other floral organs and ultimately the grain. The fate of the spikelet determines reproductive success and contributes toward yield-related traits in cereal crops. Here, we examined the transcriptional landscapes of floral meristems in the temperate crop barley (Hordeum vulgare L.) using RNA-seq of laser capture microdissected tissues from immature, developing floral structures. Our unbiased, high-resolution approach revealed fundamental regulatory networks, previously unknown pathways, and key regulators of barley floral fate and will equally be indispensable for comparative transcriptional studies of grass meristems.
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Loehrlein, Marietta, and Richard Craig. "Floral Ontogeny of Pelargonium ×domesticum." Journal of the American Society for Horticultural Science 125, no. 1 (January 2000): 36–40. http://dx.doi.org/10.21273/jashs.125.1.36.
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Floral ontogeny of two cultivars of Pelargonium ×domesticum L.H. Bailey, (regal pelargonium) `Duchess' and `Jennifer', was examined. Plants of both cultivars were grown together in a growth chamber at 15.5 °C with a photosynthetic photon flux of 10 mol·m-2·d-1. Meristems were examined at 5-day intervals over an experimental period of 170 days. The initial vegetative meristem was convex with leaf primordia initiated on either side in an alternate pattern. Early floral initiation was characterized by formation of two clefts on either side of the meristem. Between the clefts new meristems developed. Proliferation of meristems continued until numerous meristems were organized in a cluster arrangement at the apex of the shoot. New meristems lacked leaf primordia and would develop into flowers. Floral organ primordia on a floral meristem were initiated in a succession of four whorls: sepals, petals, androecia, and gynoecium.
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Wei, Wei, Robert E. Davis, Gary R. Bauchan, and Yan Zhao. "New Symptoms Identified in Phytoplasma-Infected Plants Reveal Extra Stages of Pathogen-Induced Meristem Fate-Derailment." Molecular Plant-Microbe Interactions® 32, no. 10 (October 2019): 1314–23. http://dx.doi.org/10.1094/mpmi-01-19-0035-r.
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In flowering plants, the transition of a shoot apical meristem from vegetative to reproductive destiny is a graduated, multistage process that involves sequential conversion of the vegetative meristem to an inflorescence meristem, initiation of floral meristems, emergence of flower organ primordia, and formation of floral organs. This orderly process can be derailed by phytoplasma, a bacterium that parasitizes phloem sieve cells. In a previous study, we showed that phytoplasma-induced malformation of flowers reflects stage-specific derailment of shoot apical meristems from their genetically preprogrammed reproductive destiny. Our current study unveiled new symptoms of abnormal morphogenesis, pointing to derailment of meristem transition at additional stages previously unidentified. We also found that the fate of developing meristems may be derailed even after normal termination of the floral meristem and onset of seed production. Although previous reports by others have indicated that different symptoms may be induced by different phytoplasmal effectors, the phenomenon observed in our experiment raises interesting questions as to (i) whether effectors can act at specific stages of meristem transition and (ii) whether specific floral abnormalities are attributable to meristem fate-derailment events triggered by different effectors that each act at a specific stage in meristem transition. Research addressing such questions may lead to discoveries of an array of phytoplasmal effectors.
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Clark, S. E., M. P. Running, and E. M. Meyerowitz. "CLAVATA3 is a specific regulator of shoot and floral meristem development affecting the same processes as CLAVATA1." Development 121, no. 7 (July 1, 1995): 2057–67. http://dx.doi.org/10.1242/dev.121.7.2057.
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We have previously described the phenotype of Arabidopsis thaliana plants with mutations at the CLAVATA1 (CLV1) locus (Clark, S. E., Running, M. P. and Meyerowitz, E. M. (1993) Development 119, 397–418). Our investigations demonstrated that clv1 plants develop enlarged vegetative and inflorescence apical meristems, and enlarged and indeterminate floral meristems. Here, we present an analysis of mutations at a separate locus, CLAVATA3 (CLV3), that disrupt meristem development in a manner similar to clv1 mutations. clv3 plants develop enlarged apical meristems as early as the mature embryo stage. clv3 floral meristems are also enlarged compared with wild type, and maintain a proliferating meristem throughout flower development. clv3 root meristems are unaffected, indicating that CLV3 is a specific regulator of shoot and floral meristem development. We demonstrate that the strong clv3-2 mutant is largely epistatic to clv1 mutants, and that the semi- dominance of clv1 alleles is enhanced by double heterozygosity with clv3 alleles, suggesting that these genes work in the same pathway to control meristem development. We propose that CLV1 and CLV3 are required to promote the differentiation of cells at the shoot and floral meristem.
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Laux, T., K. F. Mayer, J. Berger, and G. Jurgens. "The WUSCHEL gene is required for shoot and floral meristem integrity in Arabidopsis." Development 122, no. 1 (January 1, 1996): 87–96. http://dx.doi.org/10.1242/dev.122.1.87.
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Self perpetuation of the shoot meristem is essential for the repetitive initiation of shoot structures during plant development. In Arabidopsis shoot meristem maintenance is disrupted by recessive mutations in the WUSCHEL (WUS) gene. The defect is evident at all developmental stages and is restricted to shoot and floral meristems, whereas the root meristem is not affected. wus mutants fail to properly organize a shoot meristem in the embryo. Postembryonically, defective shoot meristems are initiated repetitively but terminate prematurely in aberrant flat structures. In contrast to wild-type shoot meristems, primordia initiation occurs ectopically across mutant apices, including the center, and often new shoot meristems instead of organs are initiated. The cells of wus shoot apices are larger and more vacuolated than wild-type shoot meristem cells. wus floral meristems terminate prematurely in a central stamen. Double mutant studies indicate that the number of organ primordia in the center of wus flowers is limited, irrespective of organ identity and we propose that meristem cells are allocated into floral whorl domains in a sequential manner. WUS activity also appears to be required for the formation of supernumerary organs in the center of agamous, superman or clavata1 flowers, suggesting that the WUS gene acts upstream of the corresponding genes. Our results suggest that the WUS gene is specifically required for central meristem identity of shoot and floral meristems to maintain their structural and functional integrity.
Dissertations / Theses on the topic "Floral meristem"
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Filho, José Hernandes Lopes. "Ontogênese do complexo de gemas em Passiflora L. (Passifloraceae) e expressão de PasAP1, ortólogo de APETALA1." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/41/41132/tde-17072015-084101/.
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A axila foliar em Passiflora L. (Passifloraceae) apresenta uma estrutura complexa: de um mesmo ponto parecem surgir flores e gavinhas, além de uma gema vegetativa também estar presente. A origem da gavinha foi interpretada de diferentes maneiras ao longo da história, sendo considerada desde modificações de um ramo até uma flor. Além disso, a ontogenia dessas estruturas tem início em um único meristema axilar, que geralmente é descrito como capaz de se dividir em dois ou mais meristemas (chamado de \"complexo de gemas\"), cada qual dando origem a uma estrutura diferente (gavinhas e flores). Estudos de expressão gênica demonstram a presença do ortólogo do gene LEAFY de Arabidopsis, em meristemas axilares, florais e de gavinhas, em duas espécies de Passiflora. Esse gene é tipicamente relacionado à transição de fase vegetativa para reprodutiva em diversas angiospermas. Assim, o presente estudo objetivou descrever em detalhes a ontogenia das diferentes estruturas originadas no meristema axilar de diferentes espécies, focando em diferentes fases de vida da planta, bem como averiguar a expressão de ortólogos de APETALA1 (AP1), um gene tipicamente relacionado à identidade de meristemas florais e na determinação de sépalas e pétalas. Como resultado, propomos uma nova interpretação para a ontogenia do complexo de gemas, baseada na produção de brácteas e seus meristemas associados. Demonstramos também que o ortólogo de AP1 se expressa de maneira mais ampla do que aquela encontrada no modelo Arabidopsis, possivelmente desempenhando diversas funções relacionadas à manutenção da indeterminação celular.The leaf axil in Passiflora L. (Passifloraceae) bears a complex structure: a tendril and one or more flowers seem to arise from the same growing point. In addition, vegetative bud is also present. There are many different interpretations for the origin of the tendril in this group, ranging from modifications of flowers to side shoots. Also, the ontogeny of these structures is often understood as a single meristem which subdivides into a bud complex, comprising the tendril and flower meristems. Recently, the expression of the LEAFY ortholog was demonstrated in the axillary, tendril and floral meristems of two Passiflora species. In Arabidopsis and many angiosperms, this gene is responsible for the shift between vegetative and reproductive phase. Therefore, the present work aimed to describe, in detail, the ontogeny of the bud complex in Passiflora species belonging to different subgenera, including different life stages. The expression of the ortholog of APETALA1, a gene typically related to floral meristem identity and sepal/petal specification was also assessed. As results, we propose a different interpretation for the ontogeny of the bud complex, based on the production of bracts and their associated meristems by the original axillary meristem, which then turns into the tendril meristem. We also demonstrate that expression of AP1 is much broader than that of the Arabidopsis model, and possibly have many other functions related to cell indeterminacy.
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Chiurugwi, Tinashe. "Molecular studies of floral meristem reversion and determinacy in Impatiens balsamina L." Thesis, University of Reading, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.428291.
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Grandi, V. "FUNCTIONAL ANALYSIS OF TRANSCRIPTION FACTORS INVOLVED IN REPRODUCTIVE MERISTEM IDENTITY IN ARABIDOPSIS THALIANA." Doctoral thesis, Università degli Studi di Milano, 2011. http://hdl.handle.net/2434/150562.
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Flowering is the most important process in a plant’s life as it is the essential step for its reproduction. Flower development starts with a tightly regulated process called the floral transition in which different regulatory pathways, which are regulated by environmental and internal signals, culminate in the transition from vegetative to reproductive growth. Subsequently, flowers develop instead of leaves and the formation of these flowers is controlled by complex regulatory pathways. In model organism Arabidopsis thaliana there are at least five different pathways that regulate the floral transition to guarantee that it occurs under the best possible conditions. The signals derived from these pathways are than integrated at the level of the floral pathway integrators which are LEAFY (LFY), FLOWERING LOCUS T (FT), SOPPRESSOR OF OVEREXPRESSION OF CO (SOC1). These genes are responsible for the switch from the shoot apical meristem (SAM) to the inflorescence meristem (IM) and are involved in the activation of the floral meristem identity (FMI) genes: LFY, LATE MERISTEM IDENTITY1 (LMI1), APETALA1 (AP1), CAULIFLOWER (CAL), SHORT VEGETATIVE PHASE (SVP) and AGAMOUS-LIKE 24 (AGL24). In fact, after the floral transition, the inflorescence meristem (IM) starts to produce floral meristems from its flanks. These meristems remain undifferentiated until stage 3 of flower development, thanks to the action of the FMI genes; afterwards, when some of these genes become repressed, the floral organs start to differentiate. In these first undifferentiated stages, the floral meristem grows and produces enough cells to support the subsequent differentiation of all the floral organs.
Many of the genes involved in these two processes, floral transition and floral meristem determination, are MADS-box transcription factors. The MADS-box family is one of the best-characterized gene families in Arabidopsis and the its members represent key regulators of developmental processes. MADS-box factors are combinatorial proteins that act via multimerization and interact with other regulatory proteins in complexes to regulate the transcription of target genes.
The aim of this thesis is the analysis of the genetic interactions of MADS-box transcription factors playing key roles during the floral transition and early stages of flower development.
The floral pathways integrator SOC1 is a MADS-box gene that integrates at least four pathways that control flowering (photoperiod, vernalization, autonomous and gibberellin pathways), giving rise to the activation of the floral meristem identity genes (Parcy, 2005).
In chapter 2, , we show that AGAMOUS-LIKE 42 (AGL42), AGAMOUS-LIKE 71 (AGL71) and AGAMOUS-LIKE 72 (AGL72) that are phylogenetically related to SOC1, are also involved in the floral transition of both the shoot apical meristem and axillary meristems and moreover, are involved in the gibberellin pathway. The soc1 agl42 ami::agl71-72 mutant shows an aerial rosettes bearing nodes phenotype. Our findings suggest that the SOC1-like genes are involved in the floral transition especially in the axillary meristem and the GA pathway is the main player controlling flowering in these axillary meristems both under short day and long day conditions. Furthermore SOC1 is able to directly control the expression of AGL42, AGL71 and AGL72 to maintain a proper expression level of SOC1-like genes.
In chapter 3, the interactions between the floral meristem identity genes SVP, AGL24, AP1, CAL, which are all MADS-box transcription factors, and LFY is described. The lfy mutant shows partial reversions of flowers in inflorescence shoot-like structures and this phenotype is enhanced in the lfy ap1 double mutant. Here we show that combining the lfy mutant with agl24, svp single or agl4 svp double mutant enhances the lfy phenotype and that the agl24 svp lfy triple mutant phenocopies the ap1 lfy double mutant. Analysis of the molecular interactions between LFY and AGL24 and SVP showed that LFY is, together with AP1, a repressor of AGL24 and SVP whereas AGL24 and SVP positively regulate AP1 and LFY by direct binding to their regulatory regions. Since all genes are important to establish floral meristem identity this regulatory loop is probably important to maintain the correct relative expression levels of these genes.
In chapter 4, we focalize our attention on SVP, a MADS-box gene involved in floral repression, before the floral transition, and in floral meristem (FM) identity determination, after the floral transition. An interesting feature of SVP is that it is the only Floral Meristem Identity Gene identified so far that is expressed exclusively in the undifferentiated FM. To date some transcription factors that are able to bind the SVP genomic region have already been identified by ChIP experiments, but it is still not clear how this gene is regulated. To understand this as a first step we are interested in the identification of the SVP minimal promoter region that fully comprises all its regulatory elements. We use, for our studies, lines that contain different SVP promoter fragments, that are cloned as transcriptional or translational fusions to the uidA gene, that encodes the beta-glucuronidase enzyme. This studies show that at least two regions are necessary for normal SVP expression: a 1 Kb fragment, located from 3000 to 2000 bp upstream of the start codon, and the first intron. In fact constructs lacking one of these two regions aren’t able to express GUS in the flower primordia.
In conclusion this work contributes to get a better understanding of what exactly happens during the floral transition and, afterwards, in undifferentiated flower meristems.
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Chu, Yi-Hsuan. "The role of LC and FAS in regulating floral meristem and fruit locule number in tomato." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1512046877370248.
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Rodas, Méndez Ana Lucía. "MtSUPERMAN controls the number of flowers per inflorescence and floral organs in the inner three whorls of Medicago truncatula." Doctoral thesis, Universitat Politècnica de València, 2021. http://hdl.handle.net/10251/171474.
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[ES] Las leguminosas son un grupo de plantas consideradas de gran importancia por su valor nutricional para la alimentación humana y ganadera. Además, las familias de leguminosas se caracterizan por rasgos distintivos de desarrollo como su inflorescencia compuesta y su compleja ontogenia floral. Para comprender mejor estas características distintivas, es importante estudiar los genes reguladores clave involucrados en el desarrollo de la inflorescencia y la flor. El gen SUPERMAN (SUP) es un factor transcripcional de dedos de zinc (Cys2-Hys2) considerado como un represor activo que controla el número de estambres y carpelos en A. thaliana. Además, SUP está involucrado en la terminación del meristemo floral y el desarrollo de los tejidos derivados del carpelo. El objetivo principal de este trabajo fue la caracterización funcional del ortólogo de SUP en la leguminosa modelo Medicago truncatula (MtSUP). Logramos este objetivo en base a un enfoque de genética reversa, análisis de expresión génica y ensayos de complementación y sobreexpresión. Nuestros resultados muestran que MtSUP es el gen ortólogo de SUP en M. truncatula. MtSUP comparte algunos de los roles ya descritos para SUP con algunas variaciones. Curiosamente, MtSUP controla la determinación del meristemo inflorescente secundario (I2) y de los primordios comunes (CP) a pétalos y estambres. Por tanto, MtSUP controla el número de flores y de pétalos-estambres que producen el meristemo I2 y los primordios comunes, respectivamente. MtSUP muestra funciones novedosas para un gen de tipo SUP, desempeñando papeles clave en los meristemos que confieren complejidad de desarrollo a esta familia de angiospermas. Este trabajo permitió identificar a MtSUP, un gen clave que forma parte de la red reguladora genética que subyace al desarrollo de la inflorescencia compuesta y de las flores en la leguminosa modelo M. truncatula.[CA] Les lleguminoses són un gran grup de plantes considerades de gran importància pel seu valor nutricional per a l'alimentació humana i ramadera. A més, les famílies de lleguminoses es caracteritzen per trets distintius de desenrotllament com la seua inflorescència composta i la seua complexa ontogènia floral. Per a comprendre millor estes característiques distintives, és important estudiar els gens reguladors clau involucrats en la inflorescència i el desenrotllament floral. El gen SUPERMAN (SUP) és un factor transcripcional de dits de zinc (Cys2-Hys2) considerat com un repressor actiu que controla el nombre d'estams i carpels en A. thaliana. A més, SUP està involucrat en la terminació del meristemo floral i el desenrotllament dels teixits derivats del carpel. "L'objectiu principal d'este treball va ser la caracterització funcional de l'ortòleg de SUP en la lleguminosa model Medicago truncatula (MtSUP) . Aconseguim l'objectiu amb base en un enfocament genètic invers, anàlisi d'expressió gènica i assajos de complementació i sobreexpressió. Els nostres resultats mostren que MtSUP és el gen ortòleg de SUP en M. truncatula. MtSUP compartix alguns dels rols ja descrits per a SUP amb variacions. Curiosament, MtSUP està involucrat en la determinació del meristemo de la inflorescència secundària (I2) i els primordios comuns (CP). Per tant, MtSUP controla el nombre de flors i pètals-estams que produïxen el meristemo I2 i els primordios comuns, respectivament. MtSUP mostra funcions noves per a un gen tipus SUP, exercint papers clau en els meristemos que conferixen complexitat de desenrotllament a esta família d'angiospermes. "Este treball va permetre identificar a MtSUP, un gen clau que forma part de la xarxa reguladora genètica darrere de la inflorescència composta i el desenrotllament de flors en la lleguminosa model M. truncatula.
[EN] Legumes are a large group of plants considered of great importance for their nutritional value in human and livestock nutrition. Besides, legume families are characterized by distinctive developmental traits as their compound inflorescence and complex floral ontogeny. For a better understanding of these distinctive features is important to study key regulatory genes involved in the inflorescence and floral development. The SUPERMAN (SUP) gene is a zinc-finger (Cys2-Hys2) transcriptional factor considered to be an active repressor that controls the number of stamens and carpels in A. thaliana. Moreover, SUP is involved in the floral meristem termination and the development of the carpel marginal derived tissues. The main objective of this work was the functional characterization of the SUP orthologue in the model legume Medicago truncatula (MtSUP). We achieved this objective based on a reverse genetic approach, gene expression analysis, and complementation and overexpression assays. Our results show that MtSUP is the orthologous gene of SUP in M. truncatula. MtSUP shares some of the roles already described for SUP with variations. Interestingly, MtSUP controls the determinacy of the secondary inflorescence (I2) meristem and the common primordia (CP). Thus, MtSUP controls the number of flowers and petal-stamens produced by the I2 meristem and the common primordia respectively. MtSUP displays novel functions for a SUP-like gene, playing key roles in the meristems that confer developmental complexity to this angiosperm family. This work allowed to identify MtSUP, a key gene that participates in the genetic regulatory network underlying compound inflorescence and flower development in the model legume M. truncatula.
I would like to thanks the Spanish Ministry of Economy and Competitiveness for the grant (MINECO; BIO2016-75485-R) that supported this work. Special thanks to the Generalitat Valenciana for funding my doctorate with the Santiago Grisolía predoctoral scholarships
Rodas Méndez, AL. (2021). MtSUPERMAN controls the number of flowers per inflorescence and floral organs in the inner three whorls of Medicago truncatula [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/171474
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Prunet, Nathanaël. "Redundancy in the temporal control of floral meristem termination in Arabidopsis thaliana : functional analysis of three modifiers of crabs claw." Lyon, École normale supérieure (sciences), 2008. http://www.theses.fr/2008ENSL0468.
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Aerial growth of Arabidopsis thaliana is realized by the shoot apical meristem (SAM), which contains stem cells whose regular divisions sustain the continuous production of new organs. During reproductive development, the SAM produces flower meristems (FMs) on its flanks. Contrary to the SAM that generated them, FMs do not grow indefinitely and produce flowers, which are determinate structures, with a fixed number of organs. This determinacy is due to the repression of WUSHEL (WUS), which confers their identity to stem cells, by the homeotic gene AGAMOUS (AG). This arrest of stem cell maintenance is linked to the female developmental program of the flower, and requires SUPERMAN (SUP), which establish the boundary between the male an female parts of the flower. During my doctorate, I realized a functional analyses of three genes, REBELOTE (RBL), SQUINT (SQN) and ULTRAPETALA1 (ULT1). Combined mutation of two of these genes, or one of them and CRABS CLAW (CRC) triggers a strong loss of FM termination, with numerous supernumerary organs being produced. The range of phenotypes we got suggests that disruption of stem cell maintenance within the FM is a progressive process, which is redundantly controlled by several genes. Genetic and molecular analyses show that our mutant phenotypes result from a down regulation of AG in a sub-domain of its expression pattern, in the centre of FM. However, this decrease of AG expression is insufficient to explain all the phenotypes we observed, and genetic data suggest that RBL, SQN and ULT1 also influence SUP function. Additionally, preliminary analyses support a role for SQN in the CLAVATA pathway, while RBL may influence microRNAs biosynthesis. Finally RBL, SQN and ULT1 seem to contribute to flower homeostasisLa croissance aérienne d’Arabidopsis thaliana est assurée par le méristème apical caulinaire (MAC), qui contient des cellules souche dont les divisions permanentes permettent la mise en place continuelle de nouvelles structures. Au cours du développement reproducteur, le MAC produit des méristèmes floraux (MFs) sur ses flancs. Contrairement au MAC et bien qu’ils en soient issus, les MFs ne présentent pas de croissance indéfinie et produisent des fleurs, qui sont des structures déterminées, constituées d’un nombre fixe d’organes. Cette détermination est liée à la répression du gène WUSHEL (WUS), qui confère leur identité aux cellules souche, par le gène homéotique AGAMOUS (AG). Cet arrêt de l’entretien des cellules souche au sein du MF est lié à la mise en place des organes femelles de la fleur, les carpelles, et requiert l’action de SUPERMAN (SUP), qui permet l’établissement de la frontière entre les parties mâle et femelle de la fleur. Le travail de cette thèse consiste en la caractérisation de trois gènes, REBELOTE (RBL), SQUINT (SQN) et ULTRAPETALA1 (ULT1). La mutation combinée de 2 de ces gènes, ou de l’un d’entre eux et de CRABS CLAW (CRC), entraîne une perte marquée de l’arrêt du MF, qui continue alors indéfiniment à produire de nouveaux organes. La gamme de phénotypes obtenus suggère que l’arrêt de l’entretien des cellules souche au centre du MF est un phénomène progressif, contrôlé de manière redondante par plusieurs gènes. Une analyse génétique et moléculaire montre que les phénotypes obtenus résultent d’une baisse d’expression d’AG dans une partie interne de son domaine d’expression, au centre du MF. Cependant, ce défaut d’expression d’AG est insuffisant pour expliquer tous les phénotypes observés, et les données génétiques obtenues suggèrent que RBL, SQN et ULT1 influencent aussi l’activité de SUP. Enfin, des études préliminaires suggèrent que SQN pourrait influencer AG via la voie CLAVATA (CLV), tandis que RBL semble jouer sur la biosynthèse des microARNs, dont une famille, miR172, affecte l’activité d’AG. Finalement, RBL, SQN et ULT1 semblent contribuer à l’homéostasie du développement floral
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Herbert, Rob. "Cellular and molecular studies on the shoot terminal meristem of Pharbitis nil Chois. cv. violet during floral evocation." Thesis, Cardiff University, 1991. http://eprints.worc.ac.uk/762/.
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Morphological, cell cycle and molecular events were studied during floral evocation in the shoot terminal meristem of the short-day plant Pharbitis nil. The haploid genome size of P.nil was 3.7 X 10e8 bp. Morphological and cell doubling time observations demonstrated that the apex widened and flattened follOwing an inductive dark treatment, the cell doubling time decreased in the peripheral zone and increased in the central zone. An inductive treatment comprising 48 h darkness given to 4 d old plants produced. 100~ flowering at the shoot terminal meristem. An inhibitory treatment was developed using 5 min RL breaks during the 48 h dark period. This treatment prevented flowering at the shoot terminal apex and discriminated between events essenttat for flowering and changes resulting from shifts from light to darkness and vice versa. It was shown using shading experiments that the shoot terminal apex may be directly involved in the reception of red-light. Maximal differences in the proportion of cells in G2/G 1 (G2/G 1 ratio) were recorded at the light/dark transition (i.e. at the end of the 48 h dark period). Apices were sampled at this time to construct floral and vegetative cDNA libraries. Less growth occurred in the central zone of the shoot apex. For example, the mitotic index of the central zone was consistently lower than that of the peripheral zone in both vegetative and induced apices. Unusual PLM curves were generated which meant that the component phases of the cell cycle were determined from microdensitometric data. The duration of the cell cycle in the peripheral zone was two-fold longer in vegetative apices compared to floral apices. However, the proportion of cycling cells (the growth fraction) was similar in the peripheral zones of both vegetative and floral apices. Following exposure to RL the duration of G2 in the peripheral zone increased five-fold. mRNA was separately extracted from 40 floral and vegetative shoot apices. The mRNA was copied into cDNA and amplified using the polymerase chain reaction. The amplified cDNA was then cloned into two A phage cDNA libraries (floral and vegetative). These libraries will form the foundation of future work on the molecular biology of floral evocation.
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Allnutt, G. V. "Characterisation of a leafy homologue, a gene regulating floral meristem identitiy, from the long day plant Silene coeli-rosa." Thesis, Cardiff University, 2000. http://eprints.worc.ac.uk/754/.
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The LFY gene, which has now been isolated in at least 17 species, is important in the transition from vegetative to reproductive growth. The floral meristems of lfy mutants exhibited increased inflorescence characteristics, and constitutive expression of the gene was sufficient to convert lateral inflorescence meristems to solitary flowers in Arabidopsis, tobacco and Populus. Previous work on the determinate plant, Silene coeli-rosa, which required 7 LD for 100% flowering, concentrated on changes to the cell cycle and peptide composition of the shoot apex during floral evocation. A partial cDNA clone of a Silene LFY homologue (SFL) has been isolated. SFL shows strong homology to other LFY homologue proteins within the two conserved domains, with up to 88% identical amino acids. It contains highly acidic and basic domains, a glutamine rich region and leucine repeats: all putat5ive transcriptional activation domains. Expression studies using quantitative PCR show that SFL was not induced by non-inductive SD conditions, or by a continuous light treatment that inhibited flowering. This is in contrast to the expression patterns observed in vegetative Arabidopsis, pea, petunia, Impatiens, tobacco and tomato, but consistent with the expression of Antirrhinum homologue which is restricted to the floral meristems. During the 7 LD induction period, SFL transcripts were first detected after 5 LD, a treatment which resulted in 81% of plants flowering, under the conditions used. Fewer than 5 LD failed to induce flowering or SFL expression. SFL was also expressed in apices subjected to an inductive 7 LD treatment followed by 48h darkness, which delayed flowering and suppressed the synchronisation of the cell cycle which occurs immediately prior to floral initiation. In situ hybridisation revealed the spatial expression of SFL in Silene. No SFL was detected prior to D7 during floral induction or in non-inductive SD controls. On experimental D7, SFL mRNA was restricted to the flanks of the primary apical dome and in D8 apices expression had spread throughout the dome. Importantly, this pattern of expression differs to that observed in the other two determinate species in which LFY has been studied, namely tobacco and Impatiens.
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Leblond-Castaing, Julie. "Caractérisation de l’interaction des protéines IMA/MIF2 et CSN5 au niveau moléculaire et physiologique." Thesis, Bordeaux 1, 2011. http://www.theses.fr/2011BOR14466/document.
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Les plantes ont la capacité à former de nouveaux organes grâce à une croissance continue assurée par une réserve de cellules souches au sein de structures spécifiques, les méristèmes. Les méristèmes floraux diffèrent des méristèmes végétatifs par leur caractère déterminé aboutissant à la production des fleurs. Le gène IMA (INHIBITOR OF MERISTEM ACTIVITY) code une protéine contenant un motif «doigt à zinc» (MIF) régulant les processus développementaux de la fleur et des ovules chez la tomate. En effet, IMA inhibe la prolifération cellulaire au cours de la terminaison florale en agissant sur l’expression du gène WUSCHEL, responsable du maintien du pool de cellules souches et contrôle le nombre de carpelles (Sicard et al., 2008). De plus, les protéines IMA et son orthologue chez Arabidopsis, MIF2, modulent la réponse à certaines phytohormones. De manière identique à la protéine MIF1 (Hu and Ma, 2006), IMA/MIF2 régule négativement la réponse aux brassinostéroïdes, à l’auxine, aux cytokinines et aux gibbérellines mais positivement la réponse à l’acide abscissique suggérant une fonction commune des protéines MIF dans les voies de réponse aux phytohormones. Un criblage d’une banque d’ADNc par la technique de double hybride a permis de révéler l’interaction entre les protéines IMA/MIF2 et une sous-unité du complexe signalosome, CSN5. De façon intéressante, les plantes mutantes csn5 d’Arabidopsis montrent de nombreuses altérations phénotypiques telles qu’un aspect buissonnant résultant de la perte de la dominance apicale, et une altération de la réponse à l’obscurité et à l’auxine. Ces phénotypes sont fortement ressemblants aux phénotypes des plantes MIF1OE d’Arabidopsis (Hu and Ma, 2006) et des plantes IMAOE de tomate (Sicard et al., 2008). Les résultats obtenus au cours de ce projet montrent que la protéine IMA inhibe la fonction du complexe signalosome grâce à son interaction avec la protéine CSN5Plants have the ability to form new organs as a result of indeterminate growth ensured by specific regions of pluripotent cells, called meristems. Flowers are produced by the activity of floral meristems which differ from vegetative meristems in their determinate fate. The INHIBITOR OF MERISTEM ACTIVITY (IMA) gene encoding a Mini Zinc Finger (MIF) protein from tomato (Solanum lycopersicum) regulates the processes of flower and ovule development. IMA inhibits cell proliferation during floral termination, controls the number of carpels during floral development and acts as a repressor of the meristem organizing centre gene WUSCHEL (Sicard et al., 2008). We demonstrated that IMA and its Arabidopsis ortholog MIF2 is also involved in a multiple hormonal signalling pathway, as a putative conserved feature for plant MIF proteins (Hu and Ma, 2006). Alike Arabidopsis MIF1, IMA/MIF2 regulates negatively BR, auxin, cytokinin and gibberellin signalling and positively ABA signaling. Using yeast two-hybrid screening experiments, we identified a strong protein-protein interaction between IMA and the signalosome subunit 5 (CSN5). Interestingly the csn5 mutant in Arabidopsis displays pleiotropic developmental defects such as a bushy phenotype originating from the loss of apical dominance and the alteration in sensitivity to darkness and auxin signals. These phenotypes are strikingly similar to what was described for Arabidopsis MIF1 (Hu and Ma, 2006) and tomato IMA overexpressors plants (Sicard et al., 2008), respectively. Taken together our data strongly suggest that IMA may act as an inhibitor of CSN function through its physical interaction with SlCSN5. The observed converse effects of IMA/MIF2 overexpression or deregulation on plant development and the abundance of developmental marker genes further support the notion of a CSN inhibitory control, since the COP9 signalosome through the specific deneddylation activity of the CSN5 subunit regulates plant hormone signalling
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Kim, Yun Ju. "Forward genetic studies towards the understanding of the molecular mechanisms underlying floral meristem determinacy and small RNA function in Arabidopsis." Diss., [Riverside, Calif.] : University of California, Riverside, 2010. http://proquest.umi.com/pqdweb?index=0&did=2019822731&SrchMode=2&sid=1&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1274208064&clientId=48051.
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Thesis (Ph. D.)--University of California, Riverside, 2010.Includes abstract. Title from first page of PDF file (viewed May 18, 2010). Includes bibliographical references. Issued in print and online. Available via ProQuest Digital Dissertations.
Books on the topic "Floral meristem"
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Claßen-Bockhoff, Regine, Louis Philippe Ronse De Craene, and Annette Becker, eds. From Meristems to Floral Diversity: Developmental Options and Constraints. Frontiers Media SA, 2021. http://dx.doi.org/10.3389/978-2-88966-827-4.
Full textBook chapters on the topic "Floral meristem"
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Fiume, Elisa, Helena R. Pires, Jin Sun Kim, and Jennifer C. Fletcher. "Analyzing Floral Meristem Development." In Plant Developmental Biology, 131–42. Totowa, NJ: Humana Press, 2010. http://dx.doi.org/10.1007/978-1-60761-765-5_9.
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Raghavan, V. "Floral Evocation and Development of the Floral Meristem." In Developmental Biology of Flowering Plants, 145–68. New York, NY: Springer New York, 2000. http://dx.doi.org/10.1007/978-1-4612-1234-8_7.
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Yanofsky, Martin F., Takashi Araki, Cindy Gustafson-Brown, Sherry A. Kempin, M. Alejandra Mandel, and Beth Savidge. "Genes Specifying Floral Meristem Identity in Arabidopsis." In Plant Molecular Biology, 51–61. Berlin, Heidelberg: Springer Berlin Heidelberg, 1994. http://dx.doi.org/10.1007/978-3-642-78852-9_6.
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Lyndon, R. F. "Meristem functioning: formation of branches, leaves, and floral organs." In Plant Development, 39–57. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-011-7979-9_3.
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Lyndon, R. F. "Meristem functioning: formation of branches, leaves, and floral organs." In Plant Development, 39–57. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-011-6844-1_3.
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Monfared, Mona M., and Jennifer C. Fletcher. "Genetic and Phenotypic Analysis of Shoot Apical and Floral Meristem Development." In Methods in Molecular Biology, 157–89. New York, NY: Springer New York, 2013. http://dx.doi.org/10.1007/978-1-4614-9408-9_7.
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Monfared, Mona M., Thai Q. Dao, and Jennifer C. Fletcher. "Genetic and Phenotypic Analysis of Shoot Apical and Floral Meristem Development." In Methods in Molecular Biology, 163–98. New York, NY: Springer US, 2023. http://dx.doi.org/10.1007/978-1-0716-3299-4_7.
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Durner, Edward F. "The Latin square design." In Applied plant science experimental design and statistical analysis using the SAS® OnDemand for Academics, 192–203. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789249927.0013.
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Abstract This chapter focuses on Latin square design. The vegetative to floral transition of the apical meristem in main crowns of strawberry plants were investigated. Five treatments was considered: (1) a control; (2) long days (16 hours) at 25°C; (3) long days at 10°C; (4) short days (8 hours) at 25°C; and (5) short days at 10°C. Experiments were set-up as a Latin square dividing each day's work schedule into five segments, thus have five rows (days), five columns (time of day) and five treatments. Results indicates that there was not much variability associated with the day of the week or the time of day for dissection.
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Kelly, Alan J., and Douglas Ry Meeks-Wagner. "Molecular Studies of Shoot Meristem Activity during the Vegetative-to-Floral Transition." In Morphogenesis in Plants, 161–79. Boston, MA: Springer US, 1993. http://dx.doi.org/10.1007/978-1-4899-1265-7_9.
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McDANIEL, C. N., S. R. SINGER, J. S. GEBHARDT, and K. A. DENNIN. "FLORAL DETERMINATION: A CRITICAL PROCESS IN MERISTEM ONTOGENY." In Manipulation of Flowering, 109–20. Elsevier, 1987. http://dx.doi.org/10.1016/b978-0-407-00570-9.50013-2.
Full textConference papers on the topic "Floral meristem"
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Venkatasubbu, Thirulogachandar. "Floral development and growth dynamics are influenced by the spatio-temporal mitotic activity of the inflorescence meristem in barley." In ASPB PLANT BIOLOGY 2020. USA: ASPB, 2020. http://dx.doi.org/10.46678/pb.20.1332422.
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Michelin, Gael, Yassin Refahi, Raymond Wightman, Henrik Jonsson, Jan Traas, Christophe Godin, and Gregoire Malandain. "Spatio-temporal registration of 3D microscopy image sequences of arabidopsis floral meristems." In 2016 IEEE 13th International Symposium on Biomedical Imaging (ISBI 2016). IEEE, 2016. http://dx.doi.org/10.1109/isbi.2016.7493464.
Full textReports on the topic "Floral meristem"
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Eshed-Williams, Leor, and Daniel Zilberman. Genetic and cellular networks regulating cell fate at the shoot apical meristem. United States Department of Agriculture, January 2014. http://dx.doi.org/10.32747/2014.7699862.bard.
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The shoot apical meristem establishes plant architecture by continuously producing new lateral organs such as leaves, axillary meristems and flowers throughout the plant life cycle. This unique capacity is achieved by a group of self-renewing pluripotent stem cells that give rise to founder cells, which can differentiate into multiple cell and tissue types in response to environmental and developmental cues. Cell fate specification at the shoot apical meristem is programmed primarily by transcription factors acting in a complex gene regulatory network. In this project we proposed to provide significant understanding of meristem maintenance and cell fate specification by studying four transcription factors acting at the meristem. Our original aim was to identify the direct target genes of WUS, STM, KNAT6 and CNA transcription factor in a genome wide scale and the manner by which they regulate their targets. Our goal was to integrate this data into a regulatory model of cell fate specification in the SAM and to identify key genes within the model for further study. We have generated transgenic plants carrying the four TF with two different tags and preformed chromatin Immunoprecipitation (ChIP) assay to identify the TF direct target genes. Due to unforeseen obstacles we have been delayed in achieving this aim but hope to accomplish it soon. Using the GR inducible system, genetic approach and transcriptome analysis [mRNA-seq] we provided a new look at meristem activity and its regulation of morphogenesis and phyllotaxy and propose a coherent framework for the role of many factors acting in meristem development and maintenance. We provided evidence for 3 different mechanisms for the regulation of WUS expression, DNA methylation, a second receptor pathway - the ERECTA receptor and the CNA TF that negatively regulates WUS expression in its own domain, the Organizing Center. We found that once the WUS expression level surpasses a certain threshold it alters cell identity at the periphery of the inflorescence meristem from floral meristem to carpel fate [FM]. When WUS expression highly elevated in the FM, the meristem turn into indeterminate. We showed that WUS activate cytokinine, inhibit auxin response and represses the genes required for root identity fate and that gradual increase in WUCHEL activity leads to gradual meristem enlargement that affect phyllotaxis. We also propose a model in which the direction of WUS domain expansion laterally or upward affects meristem structure differently. We preformed mRNA-seq on meristems with different size and structure followed by k-means clustering and identified groups of genes that are expressed in specific domains at the meristem. We will integrate this data with the ChIP-seq of the 4 TF to add another layer to the genetic network regulating meristem activity.
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Lifschitz, Eliezer, and Elliot Meyerowitz. The Relations between Cell Division and Cell Type Specification in Floral and Vegetative Meristems of Tomato and Arabidopsis. United States Department of Agriculture, February 1996. http://dx.doi.org/10.32747/1996.7613032.bard.
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Meristems were the central issue of our project. Genes that are required for cell division, cell elongation, cell proliferation and cell fate were studied in the tomato system. The analysis of the dUTPase and threonine deaminase genes, along with the dissection of their regulatory regions is completed, while that of the RNR2 and PPO genes is at an advanced stage. All these genes were isolated in our laboratory. In addition, 8 different MADS box genes were studied in transgenic plants and their genetic relevances discovered. We have also shown that a given MADS box gene can modify the polarity of cell division without affecting the fate of the organ. In vivo interaction between two MADS box genes was demonstrated and the functional dependency of the tomato agamous gene on the TM5 gene product established. We have exploited the Knotted1 meristematic gene in conjunction with tomato leaf meristematic genes to show that simple and compound leaves and, for that matter, sepals and compound leaves, are formed by two different developmental programs. In this context we have also isolated and characterized the tomato Knotted1 gene (TKnl) and studied its expression pattern. A new program in which eight different meristematic genes in tomato will be studied emerged as a result of these studies. In essence, we have shown that it is possible to study and manipulate plant developmental systems using reverse genetic techniques and have provided a wealth of new molecular tools to interested colleagues working with tomato. Similarly, genes responsible for cell division, cell proliferation and cell fate were studied in Arabidopsis floral meristems. Among these genes are the TSO1, TSO2, HANABA TARANU and UNUSUAL FLORAL ORGANS genes, each affecting in its own way the number of pattern of cell divisions, and cell fate, in developing Arabodopsis flowers. In addition, new methods have been established for the assessment of the function of regulatory gene action in the different clonal layers of developing floral meristems.
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Wagner, D. Ry, Eliezer Lifschitz, and Steve A. Kay. Molecular Genetic Analysis of Flowering in Arabidopsis and Tomato. United States Department of Agriculture, May 2002. http://dx.doi.org/10.32747/2002.7585198.bard.
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The primary objectives for the US lab included: the characterization of ELF3 transcription and translation; the creation and characterization of various transgenic lines that misexpress ELF3; defining genetic pathways related to ELF3 function regulating floral initiation in Arabidopsis; and the identification of genes that either interact with or are regulated by ELF3. Light quality, photoperiod, and temperature often act as important and, for some species, essential environmental cues for the initiation of flowering. However, there is relatively little information on the molecular mechanisms that directly regulate the developmental pathway from the reception of the inductive light signals to the onset of flowering and the initiation of floral meristems. The ELF3 gene was identified as possibly having a role in light-mediated floral regulation since elj3 mutants not only flower early, but exhibit light-dependent circadian defects. We began investigating ELF3's role in light signalling and flowering by cloning the ELF3 gene. ELF3 is a novel gene only present in plant species; however, there is an ELF3 homolog within Arabidopsis. The Arabidopsis elj3 mutation causes arrhythmic circadian output in continuous light; however, we show conclusively normal circadian function with no alteration of period length in elj3 mutants in dark conditions and that the light-dependent arrhythmia observed in elj3 mutants is pleiotropic on multiple outputs regardless of phase. Plants overexpressing ELF3 have an increased period length in constant light and flower late in long-days; furthermore, etiolated ELF3-overexpressing seedlings exhibit a decreased acute CAB2 response after a red light pulse, whereas the null mutant is hypersensitive to acute induction. This finding suggests that ELF3 negatively regulates light input to both the clock and its outputs. To determine whether ELF3's action is phase dependent, we examined clock resetting by light pulses and constructed phase response curves. Absence of ELF3 activity causes a significant alteration of the phase response curve during the subjective night, and overexpression of ELF3 results in decreased sensitivity to the resetting stimulus, suggesting that ELF3 antagonizes light input to the clock during the night. Indeed, the ELF3 protein interacts with the photoreceptor PHYB in the yeast two-hybrid assay and in vitro. The phase ofELF3 function correlates with its peak expression levels of transcript and protein in the subjective night. ELF3 action, therefore, represents a mechanism by which the oscillator modulates light resetting. Furthermore, flowering time is dependent upon proper expression ofELF3. Scientifically, we've made a big leap in the understanding of the circadian system and how it is coupled so tightly with light reception in terms of period length and clock resetting. Agriculturally, understanding more about the way in which the clock perceives and relays temporal information to pathways such as those involved in the floral transition can lead to increased crop yields by enabling plants to be grown in suboptimal conditions.