Academic literature on the topic 'Dehiscent fruit'

Dry fruits consist of two types, dehiscent and indehiscent, whereby the fruit is splitting open or remains closed at maturity, respectively. The seed, the dispersal unit (DU) of dehiscent fruits, is composed of three major parts, the embryo and the food reserve, encapsulated by the maternally-derived organ, the seed coat. Indehiscent fruit constitutes the DU in which the embryo is covered by two protective layers (PLs), the seed coat and the fruit coat. In grasses, the caryopsis, a one-seeded fruit, can be further enclosed by the floral bracts to generate two types of DUs, florets and spikelets. All protective layers enclosing the embryo undergo programmed cell death (PCD) at maturation and are thought to provide mainly a physical shield for embryo protection and a means for dispersal. In this review article, I wish to highlight the elaborate function of these dead organs enclosing the embryo as unique storage structures for beneficial substances and discuss their potential role in seed biology and ecology.

Fruits exhibit highly diversified morphology, and are arguably one of the most highly specialised organs to have evolved in higher plants. Fruits range in morphological, biomechanical, and textural properties, often as adaptations for their respective dispersal strategy. While most plant species possess monomorphic (of a single type) fruit and seeds, here we focus on Aethionema arabicum (L.) Andrz. ex DC. (Brassicaceae). Its production of two distinct fruit (dehiscent and indehiscent) and seed types on the same individual plant provides a unique model system with which to study structural and functional aspects of dimorphism. Using comparative analyses of fruit fracture biomechanics, fracture surface morphology, and internal fruit anatomy, we reveal that the dimorphic fruits of A. arabicum exhibit clear material, morpho-anatomical, and adaptive properties underlying their fracture behaviour. A separation layer along the valve–replum boundary is present in dehiscent fruit, whereas indehiscent fruit have numerous fibres with spiral thickening, linking their winged valves at the adaxial surface. Our study evaluates the biomechanics underlying fruit-opening mechanisms in a heteromorphic plant species. Elucidating dimorphic traits aids our understanding of adaptive biomechanical morphologies that function as a bet-hedging strategy in the context of seed and fruit dispersal within spatially and temporally stochastic environments.

Two fossil fruit types and at least one fossil leaf type representing Trochodendraceae are recognized from the middle Miocene Cascadia flora of western Oregon, USA. Trochodendron rosayi sp. nov., known also from the middle Miocene of eastern Oregon and northern Idaho, is based on long-pedicelled, apically dehiscent capsular fruits with 7-9 persistent outcurved styles, very similar to the extant monotypic east Asian species T. aralioides. Concavistylon kvacekii gen. et sp. nov. is named for a racemose infructescence bearing shortly pedicellate, apically dehiscent capsules with 4 to 5 persistent incurved styles arising from the basal 1/3 of the fruit. Leaves associated at the Moose Mountain locality are recognized as Trochodendron postnastae sp. nov. They have basally acrodromous venation with a prominent midvein bracketed by a pair of strongly ascending basal secondaries and are thought to correspond to the T. rosayi fruits. These new occurrences demonstrate that greater diversity was present among fossil Trochodendraceae than previously recognized during the Miocene in western North America.

ABSTRACTPatterns of fruit production were monitored over a 1-year period, from June 1990–May 1991, by counting the numbers of freshly fallen ripe and unripe fruits on five 5-km line transects located within 35 km of one another, in lowland tropical rainforest in the Lopé Reserve, central Gabon. A total of 195 species of fruit were found, representing at least 45 taxonomic families. The majority of fruits came from trees. Fruits were assigned to one of six categories which reflected their dispersal syndrome: succulent, arillate, dehiscent, fleshy pods, wind-dispersed, others. About three-quarters of all species had fruits characteristic of those dispersed by animals. There was a marked seasonal pattern to fruit production, with both the diversity and number of ripe fruits available peaking in January, and lowest immediately before and during the major dry season. The only climatic variable that showed a significant statistical correlation with fruit production was insolation. Candidates for the role of keystone fruit species were identified from species which fruited during the major dry season, and patterns of fruit production compared with other areas.

Asian hornbills are primarily frugivorous. We studied the characteristics of fruits consumed by four sympatric hornbill species in Thailand: Great Hornbill (Buceros bicornis), Wreathed Hornbill (Aceros undulatus), Austin's Brown Hornbill (Anorrhinus austeni) and Oriental Pied Hornbill (Anthracoceros albirostris). We compared the frequency of distribution of 11 variables for all fruit species collected in the study area (n = 259) and fruit species consumed by hornbills (n = 73). Our analysis revealed that fruits consumed by hornbills are: (1) large, (2) easily accessible within the canopy, (3) red, purple or black and (4) dehiscent or indehiscent with a thin husk. The range of fruit sizes eaten by hornbills in our study is comparable to that reported from other sites in Southeast Asia and Africa. The large gape width of hornbills enables them to consume large fruits that small frugivores would find difficult to consume.

Lack of pollen dispersal was noted in various sites and cultivars of sweet cherry (Prunus avium) following one of California's warmest recorded winters (≈550 hours @ 7°C in the Central Valley). `Bing' cherry is thought to require 850 to 880 hours for adequate budbreak and bloom development. Cross pollination is required by most sweet cherry cultivars for fruit set, including `Bing'. Complete anther dehiscence averaged 13% in `Bing' trees sampled, compared to 52% in `Rainier', 65% in `Brooks', 84.5% in `Burlat', 33% in Van, 23% in `Larian', and 86% in `Black Tartarian'. A range of degree of dehiscence from none to half-open was widely apparent, again by cultivar. Many partially dehiscent anthers did not shed pollen normally but appeared to have the mass of pollen completely adherent inside the pollen sacs. `Black Tartarian', `Larian', and `Burlat' shed pollen readily, however, pollen from dehiscent anthers of other cultivars generally appeared to stick together on the everted locule walls and required direct manipulation to be withdrawn from the pollen sac. Anther morphology ranged from normal size to half normal size, anthers appearing to be without pollen altogether that shriveled on drying, and lobes that were aborted. Pollen germination was low overall: 19% `Bing', 18% `Rainier', 20% `Brooks', 57% `Burlat', 14% `Van', 48% `Larian', and 48% `Black Tartarian'. Poor fruit set in low chill years is often attributed to lack of bloom overlap with pollenizers, however, inadequate chilling also may contribute to low fruit set by inhibiting anther and pollen growth and development. The implications of a critical chilling requirement for normal floral differentiation are that in cherry-growing areas where low chill years are common, pollen may not be viable or transferrable from pollenizers and female gametophytic development also may be impaired.

Abstract An anatomically preserved fossil fruit Allericarpus parvivalvis (Bayer) J. Kvaček et Heřmanová comb. nov. is described from the Coniacian of Březno (Březno Formation), from the Bohemian Cretaceous Basin. Its morphology is characterised based on x-ray and SEM studies. It shows a pentamerous fruit consisting of loculicidally dehiscent capsules. The fruit is subtended by thin persistent sepals. The taxon is compared to other similar taxa, particularly to two earlier described fossil species of Allericarpus. All its characters indicate relationship with the family Pentaphylacaceae of the order Ericales.

The vegetative and floral morphology of the Tasmanian endemic Anodopetalum biglandulosum is re-examined and illustrated. A detailed study of herbarium and fresh material identified a number of characters that have, in the past, been misinterpreted. The subsidiary cell arrangement around the stomates is brachyparacytic, and not anomocytic; the petals are shown to be notched, and not entire; the fruit is a weakly lignified, septicidally dehiscent capsule, not a berry, and the pollen is dicolporate, not tricolporate as has been previously reported. The two- and three-flowered inflorescences and solitary flowers are interpreted as a reduced cyme, while the leaf is interpreted as a unifoliolate compound leaf. The vegetative and floral morphology in Anodopetalum is compared with the closely related genera Schizomeria, Platylophus and Ceratopetalum. Features including notched/fringed petals, dicolporate pollen with a discontinuous (heterogeneous) tectum and weakly heterogeneous wood rays provide support for interpreting Anodopetalum, Schizomeria, Platylophus and Ceratopetalum as a monophyletic group. Anodopetalum differs from these genera in its strongly dehiscent fruits and winged seeds.

Rutaceae consiste em cerca de 150-164 gêneros e 1500-2000 espécies, com distribuição predominantemente pantropical. Estudos sobre anatomia de frutos e ontogenéticos de órgãos reprodutivos em Rutaceae dentro de um contexto evolutivo são escassos. Nesse contexto, este trabalho tem como objetivo analisar as características anatômicas através da ontogenia de frutos em espécies da subtribo Galipeeae, visando conhecer a origem das camadas pericárpicas para o estabelecimento de homologias e diferenças estruturais entre os frutos deiscentes e indeiscentes. Além disso, características morfológicas tais como endocarpo elástico, tipo de fruto e grau de conação de carpelos foram inferidos a luz de uma filogenia molecular a fim de discutir a classificação infrafamiliar de Rutaceae, bem como auxiliar na identificação de sinapomorfias que sustentem os clados. Para tanto foram escolhidas as espécies Balfourodendron riedelianum, Conchocarpus minutiflorus, Conchocarpus pentandrus, Ertela trifolia, Esenbeckia febrifuga, Esenbeckia leiocarpa, Galipea jasminiflora, Helietta apiculata e Hortia oreadica que abrangem os grandes clados na tribo que representam a variação na morfologia dos frutos. Zanthoxylum rhoifolium (tribo Zanthoxyleae), foi usado como grupo externo para comparação com os resultados de Galipeeae. Os estudos ontogenéticos foram realizados a partir de material coletado ou de herbário e incluídos em resina para todos os estádios de flores e frutos. Os resultados ontogenéticos mostraram diferenças estruturais tais como a disposição cruzada do endocarpo lignificado e a linha de deiscência correlacionados com a abertura dos frutos. A reconstrução dos estados de caráter ancestrais propôs que as classificações inframiliares de Rutaceae são baseadas em caracteres plesiomórficos. Estudos aprofundados baseados em caracteres anatômicos, morfológicos e moleculares devem ser integrados afim de propor uma nova circunscrição e suporte para os clados.
Rutaceae consists of c. 150-164 genera and 1500-2000 species, with predominantly pantropical distribution. Studies on the anatomy of fruits and ontogeny of reproductive organs in Rutaceae within an evolutionary context are still scarce. In this context, the objective of this work is to analyze anatomical characteristics of the fruits in species of the tribe Galipeeae in an ontogenetic context, aiming at to verify the origin of the pericarp layers for the establishment of homologies and structural differences between the dehiscent and indehiscent fruits. In addition, morphological characteristics such as the elastic endocarp, fruit type and degree of conation of the carpels were inferred in light of a molecular phylogeny in order to discuss the infrafamilial classification of Rutaceae, as well as to help identify the synapomorphies that support the clades. Balfourodendron riedelianum, Conchocarpus minutiflorus, Conchocarpus pentandrus, Ertela trifolia, Esenbeckia febrifuga, Esenbeckia leiocarpa, Galipea jasminiflora, Helietta apiculata and Hortia oreadica, which represent the large clades in the tribe and fruit variation were used. Zanthoxylum rhoifolium (tribe Zanthoxyleae), was used as out-group for comparison with the results of Galipeeae. Ontogenetic studies were carried out from collected material or from herbarium specimens and included in resin for all stages of flowers and fruits. The ontogenetic results showed structural differences such as the cross-arrangement of the lignified endocarp and the dehiscence line correlated with the opening of the fruits. The reconstruction of the ancestral character states proposed that the traditional inframiliary Rutaceae classifications are based on plesiomorphic characters and that new comparative and ontogenetic anatomical studies may be useful in understanding the evolutionary history of the family as a whole.

Dehiscence is a means by which some wild plants release their seeds. In Brassicas the mature fruit or 'pod', strictly a silique, releases seed by a sometimes explosive mechanism triggered by mechanical pressure and referred to as 'shatter'. This mechanism is a problem in Brassica crop plants and results in loss of seed, and hence loss of revenue, during harvesting. This problem is further compounded by the distribution of volunteers which contaminate future crops and the environment. The post-fertilisation development of the carpel wall of a number of Brassica species has been examined including, a range of Arabidopsis ecotypes and mutants, and fruits from two other Brassicas, Brassica napus and Brassica juncea, which exhibit differences in the dehiscence characteristic. These have been studied by a combination of cytological, cytochemical and molecular techniques. Following fertilisation, dehiscence zones form at the carpel margins, separating the carpel walls from the replum and forming two valves. Cells within the dehiscence zone exhibit reduced cellular cohesion due to breakdown of the middle lamella. Differentiation of the carpel wall layers results in a thickened exocarp, a senescing mesocarp, and modification of the endocarp layers in which the inner layer Enϸ lignifies whilst Enα collapses. It is proposed that the patterns of differentiation result in the development of the dehiscence mechanism. The dehiscence mechanism and pod 'shatter' is a result of; 1) weakening of valve attachment due to reduced cell cohesion in the dehiscence zone, and, 2) tensions which develop within the carpel walls due to desiccation and shrinkage of the mesocarp which is attached to a thickened, non-shrinking endocarp.The fruits from all of the Arabidopsis ecotypes examined exhibited a similar pattern of carpel wall development and similar dehiscence characteristics. Light microscopical examination of the fruits of Brassica napus and Brassica juncea which do not shatter as easily as those of Arabidopsis showed a different pattern of endocarp development in the post fertilised fruit. Enα tangential walls thickened considerably in the post-fertilised Brassica napus and Brassica juncea fruit, prior to the collapse of this cell layer. In Indian mustard, the Brassica juncea variety which had a non-shattering phenotype, the lignified walls of En6 were surrounded by a highly pectinised layer. This deposition of pectins confers more elasticity to the carpel walls, hence reducing the tensions which normally result in dehiscence and cause pod shatter. The model of the shattering and non-shattering phenotypes described in this study suggest a number of strategies which may be used to reduce the problems of pod shatter. These include modification of the separation layer to increase cellular cohesion, and modifications to the patterns of differentiation in the carpel wall to reduce the tensions which normally develop during fruit ripening.

Orientador: Sandra Maria Carmello Guerreiro
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: A morfologia externa e interna dos frutos e sementes de Passifloraceae Juss. ex Roussel é pouco conhecida ou até desconhecida para muitas espécies. Estudos morfoanatômicos de frutos e sementes têm grande importância já que os mesmos exibem pequena plasticidade fenotípica. Neste contexto, este trabalho teve como objetivo elucidar a ontogenia do fruto e da semente de quatro espécies de Passiflora L. subgênero Decaloba (DC.) Rchb. superseção Decaloba (DC.) J.M. Macdougal & Feulliet seção Xerogona (Raf.) Killip que apresentam frutos do tipo cápsula, condição incomum na família. Para tanto, o material vegetal foi coletado e processado segundo técnicas convencionais em microscopia de luz e eletrônica, além da aplicação de técnica específica (TUNEL) para detecção de morte celular programada no estádio de deiscência do fruto. Foram estabelecidos estádios de desenvolvimento para os frutos e as sementes: Estádio I: Ovário e óvulo; Estádio II - fruto e semente em início de desenvolvimento: frequentes divisões celulares; Estádio III - fruto e semente jovens: alongamento celular; Estádio IV - fruto e semente maduros: diferenciação celular e deiscência do fruto. Nos estádios II a IV do fruto, o epicarpo e o endocarpo são uniestratificados e as maiores modificações decorrentes do desenvolvimento do fruto ocorrem no mesocarpo. Ao longo do desenvolvimento aumentam os espaços intercelulares a partir do endocarpo em direção ao epicarpo. Não há a formação de uma linha de deiscência. Os espaços intercelulares ocorrem devido à morte celular programada formando lacunas que acabam por romper o pericarpo. Os testes histoquímicos indicaram a presença de idioblastos contendo compostos fenólicos e proteínas no tecido fundamental do ovário e no mesocarpo. As sementes das espécies estudadas são bitegumentadas. A testa é constituída de duas camadas: exotesta e endotesta. O tégmen é composto por três camadas: exotégmen, mesotégmen e endotégmen. No início do desenvolvimento da semente observou-se o arilo de origem funicular, formado por células parenquimáticas e idioblastos contendo compostos fenólicos e amido. O desenvolvimento dos tegumentos da semente se dá pelo alongamento diferencial das células do exotégmen e da endostesta. Esse processo resulta na ruminação do endosperma. Na semente madura o tegumento externo formará a sarcotesta. Neste estádio, o exotégmen constitui a camada mecânica formada por macroesclereídes em paliçada, representando a esclerotesta. As informações encontradas no presente estudo revelam que as características morfoanatômicas de fruto e semente são bastante conservadas e unificadoras na seção. Diante do exposto, destaca-se a importância de novos estudos abrangendo mais espécies e abordando a evolução de caracteres e a inclusão de outros novos para facilitar a elucidação das relações infragenéricas de Passiflora que tem sido ampliada graças à cooperação de estudos morfoanatômicos e genéticos
Abstract: External and internal morphology of Passifloraceae Juss. ex Roussel fruits and seeds is little known or even unknown for many species. Morphological and anatomical studies of fruits and seeds have great importance since they exhibit little phenotypic plasticity. In this context, this study aimed to elucidate the fruit and seed ontogeny of four species of Passiflora L. Decaloba (DC.) Rchb. subgenus Decaloba (DC.) J.M. Macdougal & Feulliet supersection Xerogona (Raf.) Killip section that present capsule type of fruit, unusual condition in the family. For this, the plant material were collected and processed according to conventional techniques for light and electron microscopy; specific technique (TUNEL) were also applied to detect programmed cell death in the stage of fruit dehiscence. Four developmental stages were established: Stage I: Ovary and ovule; Stage II - fruit and seed in early development: frequent cell divisions; Stage III - young fruit and young seed: cell elongation; Stage IV - mature fruit and mature seed: cell differentiation and fruit dehiscence. In the stages II to IV of the fruit, epicarp and endocarp are unistratified and major changes from the development of the fruit occurs on mesocarp. During the development, the intercellular spaces increase from the endocarp towards the epicarp. There is no line of dehiscence. The intercellular spaces occur due to programmed cell death forming gaps that breaks the pericarp. Histochemical test indicated the presence of phenolic compounds and idioblasts containing proteins in fundamental tissue of ovary and mesocarp. The seeds of all species were bitegmic. The testa consists of two layers: exotesta and endotesta. The tegmen is composed of three layers: exotegmen, mesotegmen and endotegmen. At the beginning of seed development, aryl of funicular origin, formed by parenchyma cells that may containing phenolic compounds and starch, was observed. The development of the integument of the seed occurs by differential cell elongation of exotegmen and endostesta. This process results in a ruminate endosperm. In the mature seed, the outer integument forms the sarcotesta. At this stage, the exotegmen is the mechanical layer formed by macrosclereids in palisade, representing esclerotesta. Information found in this study reveals that morphoanatomical characteristics of fruit and seed are quite conserved and unified in the section. Given that, we highlight the importance of further studies including more species and addressing the evolution of characters and adding new ones to facilitate the elucidation of infrageneric relationships in Passiflora which has been expanded due to the cooperation of morpho-anatomical and genetic studies
Doutorado
Biologia Vegetal
Doutora em Biologia Vegetal