Association genetics to identify genes involved in aggressiveness traits in the plant pathogenic fungus Mycosphaerellafijiensis

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Association genetics to identify genes involved in

aggressiveness traits in the plant pathogenic fungus

Mycosphaerellafijiensis

Léa Picard, Jean Carlier, Sébastien Ravel

To cite this version:

Léa Picard, Jean Carlier, Sébastien Ravel. Association genetics to identify genes involved in aggres-siveness traits in the plant pathogenic fungus Mycosphaerellafijiensis. 8. edition of the Printemps de Baillarguet, Jun 2016, Montferrier-Sur-Lez, France. 68 p. �hal-02739122�

Association genetics to identify genes involved

in aggressiveness traits in the plant pathogenic

fungus Mycosphaerellajiensis

Léa PICARD1,*_{, Jean CARLIER}1_{, Sebastien RAVEL}1

1. UMR BGPI (INRA, CIRAD, SupAgro), Campus International de Baillar-guet, 34398 Montpellier Cedex 05, France.

* Corresponding author : lea.picard@cirad.fr

Abstract The fungal pathogen Mycosphaerellajiensis causing black leaf streak disease of banana may be able to adapt to quantitatively resistant cultivars through changes in its aggressiveness. To understand this adapta-tion, it is necessary to determine the genetic basis of the aggressiveness traits involved. This study aims to identify genes of aggressiveness traits using a genome wide association study (GWAS) approach.

About 130 M. jiensis isolates were collected on susceptible and quantitati-vely resistant banana trees in three dierent locations in Cuba. The genome of these isolates was then sequenced and SNP (single nucleotide polymor-phism) calling was performed. There was low genetic structure between the three Cuban populations (Fst=0.055). Linkage disequilibrium (LD) declined to 50% within about 6kb. The population mutation rate theta rst estimate was 0.06%.

A phenotype study was conducted to assess some aggressiveness traits using inoculations under controlled conditions : the number of symptoms and their total surface. Based on our variance analysis, we decided to use a simplied linear model taking only the cultivar and isolate eects into account, to calculate least-square means.

These preliminary analyses showed that the samples analyzed satisfy condi-tions to conduct a GWAS analysis (reasonable LD, limited population struc-ture and phenotypic variability for the quantitative traits considered). Such a study is currently being performed using the GAP-IT R package.

Keywords : Association genetics, variant calling, aggressiveness, GWAS, fungal pathogen

Proceedings

8th _{edition of the Printemps de Baillarguet}