Genome-wide association mapping for Sclerotinia Head Rot resistance in sunflower.

FILIPPI, C.V.; AGUIRRE N.; ZUBRZYCKI, J.E.; DI RIENZO, J.A.; MONTECCHIA JF; GONZALEZ S.; RIVAROLA M.; QUIROZ F.; ALVAREZ, D.; HOPP H.E.; HEINZ R.A.; LIA V.V.; PANIEGO, N.B.

Montevideo

Congreso; XVI Congreso Latinoamericano de Genética; 2016

ALAG

Argentina has a long tradition in sunflower breeding, and its distinct germplasm is a valuable genetic resource for crop improvement. During the last five years we evaluated the response of 135 sunflower inbred lines from the INTA?s breeding program to Sclerotinia Head Rot (SHR), one of the most devastating diseases in all sunflower growing areas. Disease incidence, severity and incubation period were registered after assisted inoculation with the pathogen in replicated field trials. Significant variability for resistance to SHR was found for all phenotypic variables. To identify and characterize new sources of disease resistance, we conducted a genome-wide association mapping study (GWAS). Plants were genotyped using the double digest RADseq (ddRADseq) approach combining SphI and EcoRI restriction enzymes. Illumina sequencing data were processed through a custom bioinformatics workflow, and single nucleotide polymorphisms (SNPs) were called using Stacks. Data was filtered for quality, and loci with >30% missing data and minor allele frequency lower than 5 % were discarded. A total of 5,270 genomic regions, totaling 19,444 SNPs were considered for GWAS. Mixed linear models accounting for population structure and kinship relatedness were used for the statistical analysis of phenotype-genotype associations. GWAS results are discussed and compared to previous candidate gene studies. The ddRADseq approach provided a powerful tool to gain new insights into the genetic basis of SHR resistance and emerged as a promising platform for crop molecular breeding.