Functional characterization of wheat, fusarium head blight resistance (QTL) «Fhb1» based on non-target metabolomics and proteomics
Notice bibliographique
Résumé
Fusarium head blight (FHB) caused by Fusarium graminearum is a dreadful disease of wheat (Triticum aestivum L.). Host resistance to FHB in wheat is quantitatively inherited. Though more than 100 QTLs have been identified, only a few have been validated. However, the resistance mechanisms governed by these QTLs are poorly understood. A type II FHB resistance QTL Fhb1 is the most consistent and largest effect QTL in wheat against FHB spread in wheat. Non-targeted metabolic and proteomic profiling of wheat near isogenic lines (NILs) with resistant and susceptible Fhb1 alleles was used to functionally characterize Fhb1 using a high resolution LC-MS. The Fhb1 from a moderately resistant cultivar Nyubai was associated with cell wall thickening, mainly at the rachis, due to deposition of hydroxycinnamic acid amides (HCAAs), phenolic glucosides and flavonoids. A hypothetical protein coding gene (GenBank: CBH32656.1) near Fhb1 locus was putatively identified as hydroxycinnamoyl transferase, which catalyzes the biosynthesis of HCAAs. Deoxynivalenol (DON) accumulation was high in both the NILs, eliminating DON detoxification as a mechanism associated with Fhb1 (Chapter III). For additional confirmation, the Fhb1 resistant allele, from a highly FHB resistant cultivar Sumai-3 was profiled. Even though the DON accumulation was low in resistant NIL, the detoxification of DON by host UDP-glycosyltransferase was moderately high in both the NILs, with no significant difference. Interestingly, unlike in the resistant NIL, constitutively present glycerophospholipids were absent in the susceptible NIL following pathogen inoculation due to degradation of membrane. Membrane degradation was caused due to programmed cell death as evidenced by DNA laddering in the susceptible NIL. A locus TAA_ctg0954b.00390.1 was identified as an Fhb1 candidate gene that contains a calmodulin binding motif and two nucleolar localization signal motifs and hence re-annotated as calmodulin binding protein (TaCaMBP_Fhb1). The TaCaMBP_Fhb1 is induced following pathogen infection, binds to Ca2+ bound calmodulin, and triggers Ca2+ signalling cascade including transcriptional activation of endonucleases that cleaves the genomics DNA and cause programmed cell death. The resistant allele of TaCaMBP_Fhb1 lacks part of the promoter region and is non-functional in triggering Ca2+ signalling. While the susceptible allele of TaCaMBP_Fhb1, with functional promoter region is capable of triggering Ca2+ signalling and programmed cell death. The necrotrophic pathogen F. graminearum feeds on the dead tissue, multiply in the host and produce more DON, following a repeated cycle in the susceptible genotype (Chapter IV). The wheat resistance mechanisms against FHB were further confirmed, based on metabolic profiling of rachis, from a resistant cultivar Sumai-3 and a susceptible cultivar Roblin, for resistance against spread of a trichothecene producing (Wild: FgTri5+) and a trichothecene non- producing (mutant: FgTri5-) isolates of F. graminearum. The wild isolate repressed several host resistance mechanisms in both the cultivars due to production of DON. The FHB resistance to spread in Sumai-3 was mainly because of increased cell wall thickening, especially at rachis, due to deposition of lignin, HCAAs and flavonoids, and partially, due to induced RR metabolites which in turn reduced the fungal biomass and toxin biosynthesis. The resistance was not attributed to DON detoxification by UDP-glycosyltransferase, as it was not significant in both the cultivars confirming our previous studies (Chapter V). The resistant alleles of two Fhb1 candidate genes, identified in this study, can be suitably stacked into genome of elite cultivars to enhance FHB resistance in wheat.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».