Evaluation of Retrotransposon-based Markers for Identification of Genetic Loci Associated with Agro-morphological Characteristics and Resistance to Sclerotinia Basal Stem rotin Oily Sunflower (Helianthus annuusL.) under Filed Conditions

IntroductionSunflower (Helianthus annuus L.) is one of the most important crops grown mainly for edible oil. Sclerotinia sclerotiorum (Lib.) de Bary is a common and widespread pathogen of sunflower. Sclerotinia stem rot is one of the most damaging diseases of sunflower in world, causing average yield reductions of 10 to 20%. It causes total production loss under favorable environmental conditions. Hence, plant improvement projects must focus on creating of new genotypes with higher resistance against diseases. Resistance to S. sclerotiorum (Lib.) de Bary has been described as quantitatively inherited with additive and dominant gene effects. Identification of chromosome regions controlling partial resistance to sclerotinia stem rot can increase understanding about the genetic control of the diseases and developing cultivars with improved partial resistance. In this study, retrotranposon-based molecular markers associated with resistance to disease as well as some important agromorphological traits identified using general and mixed linear models in Tassel software.
Materials and MethodsA collection of 100 sunflower lines, kindly provided by several research centers in Europe, Iran and the United States, were evaluated using a 1010 simple lattice design with two replications. Each plot comprised 2 lines 5 m long, with a spacing of 65 × 25 cm between lines and plants, respectively. The experiment was conducted in 2015 at a farm in ‘Vaghaslo-e-Sofla’ village on Urmia. Five plants per genotype in each replication were inoculated with a fungal isolate collected from naturally infected sunflower plants of this farm in previous year.Some resistant and agronomical traits including percentage of necrotic area after 4, 8, 12 days inoculation, 100 seeds weight of non contaminated plants, 100 seeds weight of contaminated plants, yield per plant in non contaminated plants, yield per plant in contaminated plants, 100 seeds weight loss, and per plant yield loss were measured. The genetic profile of population was prepared with 28 rerotransposon markers.
Results and DiscussionBased on molecular marker data, the studied association panel was subdivided into two subpopulations (K=2). Association analysis using mixed linear model (MLM) identified 27 loci significantly (P