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Cartographie de la résistance du manioc à la bactériose vasculaire causée par Xanthomonas axonopodis pv. Manihotis

Abstract : Cassava Bacterial Blight (CBB), caused by Xanthomonas axonopodis pv. manihotis (Xam), is a major disease of cassava (Manihot esculenta Crantz) in Africa and South America. Varietal resistance, the preferred method for disease control, has been introgressed in improved varieties through intra and interspecific crosses with M. glaziovii. The purpose of this study was to understand genetics of resistance to CBB. Two populations (F1 and BC1) have been developed from crosses between two elite heterozygous varieties (TMS 30 572 and CM 2177-2) and QTL (Quantitative Trait Loci) mapping has been used. Based on the evaluation of F1 individuals, we found 12 QTL involved in greenhouse resistance to five Xam strains, and 10 QTL involved in field resistance during three crop cycles. These results revealed complexity of resistance to CBB. Futhermore, QTL detected in greenhouse were specific to particular Xam strains, suggesting interaction between plant and Xam genetic factors. In field, number of QTL detected varied during the three crop cycle and resistance was overcome at the end of the third cycle, showing that resistance was not durable. Changes in pathogen population structure, followed during the three crop cycles, could explain this breakdown of resistance. Based on the evaluation of a second population (BC1) in greenhouse, we detected at least three recessive QTL that could not be detected with F1 population. Other genetic interactions like suppression were suspected. One QTL, XM8, located on linkage group D was detected in greenhouse and in field. We evidenced that it could be resistance originating from M. glaziovii. Based on this study, we recommend molecular markers useful for marker assisted selection (MAS) and also for cloning of resistance factors.
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Submitted on : Sunday, June 7, 2020 - 3:08:10 PM
Last modification on : Monday, November 30, 2020 - 6:54:03 AM

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  • HAL Id : tel-02841765, version 1
  • PRODINRA : 479551

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Véronique Jorge. Cartographie de la résistance du manioc à la bactériose vasculaire causée par Xanthomonas axonopodis pv. Manihotis. Biologie végétale. Université Paris Sud - Paris 11, 2000. Français. ⟨tel-02841765⟩

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