Добірка наукової літератури з теми "Fruitlet Core Rot"

The identity of the fungi responsible for fruitlet core rot (FCR) disease in pineapple has been the subject of investigation for some time. This study describes the diversity and toxigenic potential of fungal species causing FCR in La Reunion, an island in the Indian Ocean. One-hundred-and-fifty fungal isolates were obtained from infected and healthy fruitlets on Reunion Island and exclusively correspond to two genera of fungi: Fusarium and Talaromyces. The genus Fusarium made up 79% of the isolates, including 108 F. ananatum, 10 F. oxysporum, and one F. proliferatum. The genus Talaromyces accounted for 21% of the isolated fungi, which were all Talaromyces stollii. As the isolated fungal strains are potentially mycotoxigenic, identification and quantification of mycotoxins were carried out on naturally or artificially infected diseased fruits and under in vitro cultures of potential toxigenic isolates. Fumonisins B1 and B2 (FB1-FB2) and beauvericin (BEA) were found in infected fruitlets of pineapple and in the culture media of Fusarium species. Regarding the induction of mycotoxin in vitro, F. proliferatum produced 182 mg kg⁻1 of FB1 and F. oxysporum produced 192 mg kg⁻1 of BEA. These results provide a better understanding of the causal agents of FCR and their potential risk to pineapple consumers.

Fruitlet Core Rot (FCR) is a fungal disease that negatively impacts the quality of pineapple, in particular the ‘Queen Victoria’ cultivar. The main FCR causal agent has been identified as Fusariumananatum. This study focused on the correlation between FCR disease occurrence, fungal diversity, and environmental factors. FCR incidence and fungal species repartition patterns were spatially contextualized with specific surrounding parameters of the experimental plots. The mycobiome composition of healthy and diseased fruitlets was compared in order to search for potential fungal markers. A total of 240 pineapple fruits were sampled, and 344 fungal isolates were identified as belonging to 49 species among 17 genera. FCR symptom distribution revealed a significant gradient that correlated to that of the most abundant fungal species. The association of wind direction and the position of proximal cultivated crops sharing pathogens constituted an elevated risk of FCR incidence. Five highly represented species were assayed by Koch’s postulates, and their pathogenicity was confirmed. These novel pathogens belonging to Fusariumfujikuroi and Talaromycespurpureogenus species complexes were identified, unravelling the complexity of the FCR pathosystem and the difficulty of apprehending the pathogenesis over the last several decades. This study revealed that FCR is an airborne disease characterized by a multi-partite pathosystem.

Pineapple is a perennial fruit-bearing tropical plant that belongs to the Bromeliaceae family, which has more than 2500 species. Pineapple is known excellent source of minerals and vitamins. It produces substantial calcium, potassium, glucose, the proteindigesting enzyme bromelain, fibre, vitamin A, B and C. In Malaysia, twelve registered varieties of pineapple have been introduced and commercially planted such as Moris (AC1), Sarawak (AC2), Gandul (AC3), Maspine (AC4), Josapine (AC5) Yankee (AC6) Moris Gajah (AC7), N36 (AC8), MD2 (AC9), View of Sunset (AC10), Madu Kaca (AC11), and Keningau Diamond (AC12). The disease is one of the important factors that can contribute to the huge losses of pineapple yield worldwide. This review paper aimed to discuss the main diseases of pineapple and their control management, particularly in Malaysia. The common diseases of pineapple that cause significant yield losses in the farms such as mealybug wilt-associated virus, bacterial heart rot, fruit collapse, butt rot, fruitlet core rot, black rot, yeasty and fusariosis are highlighted and discussed in detail on the causal pathogens, disease symptoms and signs, disease infection and development. The available control measures for managing pineapple diseases were also included in this paper.

L’interaction hôte-pathogènes à l’origine de la maladie FCR de l’ananas représente un enjeu économique important pour l’île de La Réunion puisqu’elle affecte le cultivar ‘Queen Victoria’, qui y est particulièrement sensible. Pour se défaire de cette contrainte et proposer des fruits indemnes de la maladie FCR aux consommateurs locaux, régionaux et internationaux, une solution serait de détecter les ananas infectés naturellement par des approches non-destructives applicables en post-récolte. Les recherches menées au cours de cette thèse ont participé à une compréhension approfondie des modifications biochimiques et des mécanismes de défense développés par l’ananas en cas d’attaque par les agents pathogènes responsables de la maladie FCR. Les analyses métabolomiques (LC-MS et GC-MS) ont permis de confirmer les reconfigurations qui touchent certains métabolites au niveau de la zone d’infection (dérivés d’acides hydroxycinnamiques et hydroxybenzoïques), et de révéler l’implication d’autres métabolites dont les teneurs sont localement modifiées dans les tissus internes et externes de l’ananas (oses, acides aminés). Par ailleurs, ces travaux ont surtout mis en évidence le déploiement d’une réponse systémique au sein de l’ananas, à travers des variations métaboliques touchant à la fois les fruits simples infectés et asymptomatiques (AABA, pipecolate, proline). Les approches spectroscopiques (FFFS et Vis-NIRS) ont permis d’établir qu’une réponse à l’infection est effectivement décelable par ces techniques, grâce à des différences de signatures spectrales entre les ananas infectés et sains. La FFFS a conduit à la discrimination d’échantillons d’ananas sur la base de leurs différences de composition enfluorophores. Les spectres acquis en Vis-NIR sur la peau d’ananas entiers ont également permis de classer les fruits simples sains et infectés, et dans une moindre mesure les fruits simples asymptomatiques. De plus, une corrélation a été établie entre la sévérité de l’infection et le spectre recueilli, montrant que la réponse systémique liée à la maladie FCR est détectableextérieurement. Par ailleurs, une méthode de fusion de données a révélé l’avantage de classerdes échantillons d’ananas sains et infectés en combinant différentes techniques analytiques. Les modèles ont été optimisés en utilisant les données de LC-MS et FFFS pour discriminer leséchantillons de pulpe, tandis que les données de Vis-NIRS suffisent pour classer au mieux leséchantillons de peau. En conclusion, les approches conjointes de métabolomique et de spectroscopie révèlent la complexité des réponses biochimiques qui se produisent lors de l’infection FCR, et démontrent ainsi l’intérêt de poursuivre les recherches afin d’exploiter le potentiel des techniques non-destructives dans la détection de maladie et les rendre accessible aux acteurs des filières agro-industrielles
The host-pathogen interaction responsible for pineapple FCR disease represents an important economic issue for Reunion Island since it affects the cultivar 'Queen Victoria', which is particularly susceptible. To overcome this limitation and offer FCR disease-free pineapples to local, regional and international consumers, one solution would be to detect naturally infected pineapples by non-destructive approaches applicable in post-harvest. The research conducted during this thesis contributed to a thorough understanding of the biochemical changes and defense mechanisms developed by pineapples when attacked by the pathogens causing FCR infection.Metabolomics (LC-MS and GC-MS) confirmed the reconfigurations affecting some metabolites at the site of infection (hydroxycinnamic and hydroxybenzoic acid derivatives), and revealed the involvement of other metabolites whose contents are locally altered in the internal and external tissues of the pineapple (oses, amino acids). Furthermore, this work has highlighted the establishment of a systemic response within pineapples, through metabolic variations affecting both infected and asymptomatic fruitlets (AABA, pipecolate, proline). Spectroscopic approaches (FFFS and Vis-NIRS) demonstrated that a response to the fungal infection is indeed detectable by these techniques through differences in spectral signatures between infected and healthy pineapples. FFFS enabled the discrimination of fruit samples based on their differences in fluorophore content. Vis-NIR spectra acquired on intact pineapple skin also allowed classifying healthy and infected fruitlets, and to a lesser extent asymptomatic ones. Moreover, a correlation was noticed between the severity of infection and the spectrum collected, indicating that the systemic response related to FCR disease is externally detectable. Furthermore, a data fusion method revealed the advantage of classifying healthy and infected pineapple samples by combining different analytical techniques. Models were optimized using LC-MS and FFFS datasets to discriminate pulp samples, while Vis-NIRS dataset was sufficient to best classify skin samples. To conclude, the joint metabolomics and spectroscopy approaches reveal the complexity of the biochemical responses that occur during FCR infection, and thereby demonstrate the interest of pursuing further research to exploit the full potential of nondestructive techniques in disease detection and to make them accessible to agro-industrial actors

Les cultures d’ananas de la Réunion sont soumises à une forte pression parasitaire favorisée par le climat subtropical de l’île. La maladie de la tache noire est causée par un cortège de champignons filamenteux dont Fusarium ananatum est l’espèce la plus décrite à ce jour. Le développement de taches noires dans les fruits matures constitue une problématique majeure de par son impact sur la qualité de l’ananas ‘Queen Victoria’ présentant une forte sensibilité à cette pathologie. La gestion des épisodes épidémiques repose actuellement sur des méthodes associant des pratiques culturales adaptées et l’utilisation de fongicides. Toutefois, ces stratégies s’avèrent infructueuses pour des conditions climatiques fortement favorables au développement et à la dispersion des agents pathogènes. L’accumulation de mycotoxines au sein des tissus infectés représente également une préoccupation d’envergure dans la préservation de la sécurité sanitaire des productions d’ananas. Dans l’objectif de développer de nouveaux leviers de résistance plus durables, des recherches visant à caractériser les déterminants de la sensibilité de l’ananas ‘Queen Victoria’ ont été menées sur chaque composante du pathosystème. Une approche épidémiologique a permis d’établir que l’occurrence de la tache noire est positivement corrélée à une contamination résultant d’une dispersion aérienne des spores d’espèces pathogènes. De plus, la prédominance d’espèces fongiques appartenant aux complexes Fusarium fujikuroi et Talaromyces purpureogenus au sein du mycobiome du fruit a démontré l’implication d’un cortège pathogène constitué de Fusarium proliferatum, Fusarium ananatum, Fusarium oxysporum, Fusarium sacchari, Talaromyces stollii et Talaromyces amestolkiae dans l’expression de cette pathologie. L’étude in vitro des profils d’interaction entre quatre de ces espèces a mis en évidence le pouvoir antagoniste de T. stollii sur la croissance des espèces pathogènes de Fusarium. D’importantes variations dans les concentrations en mycotoxines (fumonisines B1, B2 et beauvericine) ont également été mesurées au cours de confrontations entre les pathogènes. Enfin, l’analyse par comparaison variétale des voies de signalisation moléculaire conditionnant les réponses de défense précoces montre que la sensibilité du cultivar ‘Queen Victoria’ est en partie imputable à une faible expression constitutive des gènes impliqués dans la synthèse de protéines PR. Les résultats obtenus suggèrent la mise en œuvre d’une stratégie fongique basée sur la répression des signaux de défenses transduits chez l’ananas au cours des 72 premières heures de l’interaction hôte – pathogène menant à l’établissement de la maladie
In Reunion Island, pineapple crops are exposed to high parasitic pressure promoted by the subtropical climate of the island. The Fruitlet Core Rot (FCR) disease is caused by a set of fungal pathogenic species in which Fusarium ananatum has been the most described so far. The development of brown discoloration in mature fruits represents a major issue affecting notably the quality of the ‘Queen Victoria’ pineapple cultivar due to its high susceptibility to FCR. Until now, the management of epidemics lies on the combination of suitable agricultural practices and the use of fungicide treatments. Nevertheless, these strategies are unsuccessful in the presence of climatic conditions that favor the development and dispersion of causalagents. Mycotoxins accumulation in the flesh of infected fruits is also of concern in the preservation of sanitary quality of fruit productions. In order to develop novel alternatives for sustainable sources of FCR resistance, my research work focused on the determinants of ‘Queen Victoria’ pineapple susceptibility. An epidemiological approach permitted to establish that Fruitlet Core Rot occurrence ispositively correlated to contamination patterns resulting from aerial dispersion of the pathogen spores. Moreover, the prevalence of fungal species belonging to the complexes Fusarium fujikuroi and Talaromyces purpureogenus within the fruit mycobiome have demonstrated the role of a pathogenic fungal set composed of Fusarium proliferatum, Fusarium ananatum, Fusarium oxysporum, Fusarium sacchari, Talaromyces stollii and Talaromyces amestolkiae in the disease expression. The in vitro study of interaction profiles between four of those species have evidenced the growth antagonism of T. stollii on the pathogenic Fusarium species. Significant variations of mycotoxin contents (fumonisins B1, B2 and beauvericin) were also measured during dual culture of pathogens. Finally, the analysis based on varietal comparison of the molecular signal promoting early defense responses show that susceptibility of ‘Queen Victoria’ cultivar is partly supported by a low constitutive expression of genes involved in the synthesis of PR proteins. The results suggest a fungal strategy based on the repression of defense signal transduction in pineapple during the first 72 hours of the host - pathogen interaction leading to the disease establishment