Association analysis using SSR markers for resistance to Sclerotinia basal stem rot disease in oily sunflower (Helianthus annuus L.) under filed conditions

Sunflower (Helianthus annuus L.) is mainly cultivated for the extraction of edible oil, and Sclerotinia sclerotiorum is a pathogen in sunflower fields. The aim of this study was to indetify markers associated with resistance to Sclerotnia Scleritiorum diseases in sunflower, using association analysis. In the present experimental research, a population including 100 lines of oily sunflower was cultivated. Traits such as contamination progress after 4, 8, and 12 days, 100 seeds weight of contaminated and non-contaminated plants, contaminated and non-contaminated plant yield, 100 seeds weight loss, and yield loss were studied. The molecular profiles of germplasm were prepred with 30 microsatellite primer pairs. Genetic structure analysis of population was performed based on Bayesian model. Findings: The highest coefficient of variation was related to the yield loss (86.41%) and weight loss (78.48%), and the lowest was contamination progression after 8 and 12 days (26.47% and 20.44%), respectively. Based on the mixed linear model (MLM), 6 microsatellite markers related to traits were identified at the level of p≤0.01. The highest number of markers was associated with contamination progression after 8 days. The P733, P807, and P1256 markers were simultaneously associated with 3 traits. Four lines including RHA274, H100A-83HR4, B45-03, and Iranian line with code 28 were identified with different genetic origins and high resistance levels. According to the general linear model (GLM) and MLM, 24 and 15 SSR markers are related to the traits, respectively. The P733, P807, and P1256 markers are simultaneously associated with 3 traits.