Development of Processing Tomato Lines Resistant to <i>Xanthomonas gardneri</i>: from Screening to Breeding
Notice bibliographique
Résumé
Bacterial spot of tomato is caused by four species of Xanthomonas: X. euvesicatoria, X. vesicatoria, X. perforans and X. gardneri.The disease causes lesions on tomato leaves and black spot on fruits, leading to yield loss and nonmarketable tomatoes.The bacterial species X. gardneri has been recently implicated in outbreaks of bacterial spot in processing tomato fields in Brazil, Canada and the Mid-West United States.As chemical solutions are currently not reliable to control bacterial spot, the development of varieties resistant to X. gardneri and to the other Xanthomonas species is of primary interest.This project sought to identify sources of resistance to X. gardneri, to describe the genetic basis of the trait, and to develop strategies to improve selection for bacterial spot of tomato and for agronomic and fruit quality traits To identify sources of resistance to X. gardneri, wild and cultivated tomato accessions were evaluated for Hypersensitive Response (HR) and tested under inoculated field conditions.Both evaluation methods showed phenotypic variation explained by genetics.The results of the two assays were not significantly correlated.Field evaluation mimics natural epidemics, thus this method was the most reliable to identify sources of resistance to X. gardneri.Five S. pimpinellifolium and Four S. lycopersicum var cerasiforme accessions showed low disease levels iii in the field.S. pimpinellifolium LA2533 and S. lycopersicum var cerasiforme LA1545 were selected as sources of resistance.To simultaneously characterize the genetics of resistance to X. gardneri and introgress the trait in processing tomato background, backcross populations were developed with LA2533 and LA1545.Families were evaluated under inoculated field conditions, and genotyped with Single Nucleotide Polymorphism (SNP) markers.Four regions where significantly associated with resistance.The allele of resistance of the Quantitative Trait Loci (QTLs) on chromosome 4 and 8 originated from the processing parent.The allele of resistance of the QTLs on chromosome 6 and 11 originated from both LA2533 and LA1545.The QTL on chromosome 11 had the strongest effect on the trait.The QTL on chromosome 11 spanned 44 Mb.In order to map the loci controlling resistance to a smaller region, Individuals carrying different recombination patterns in this region were selected and their progeny were evaluated for resistance to X. gardneri under field conditions.The region associated with resistance was reduced to 10 Mb, and its effect on resistance was confirmed.The genetic effect of the region was additive to partially dominant.Selected lines derived from LA2533 showed resistance to X. gardneri, X. euvesicatoria and X. perforans under field conditions.These lines are promising breeding material to develop elite processing tomato with high performance in humid growing region with frequent bacterial spot epidemics.Approaches considering genetic information across the whole genome might be effective to breed for resistance to bacterial spot of tomato.We evaluated performance of Genomics Selection (GS) to select lines resistant to X. euvesicatoria.GS models were trained in a breeding xvi
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Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| 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 | 0,003 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 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 tête enseignante, 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 ».