Association analysis of agronomic traits of oilseed sunflower (Helianthus annuus L.) lines with REMAP and IRAP markers under optimum and phosphorus deficit stress

Sunflower (Helianthus annuus L.) is one of the most valuable agricultural products, mainly cultivated for edible oil. Phosphorus is a suitable nutrient in plants that plays key roles in several cellular structures and catalytic functions of enzymes involved in metabolism. In order to produce and develop phosphorus-efficient cultivars, 100 sunflower lines from different parts of the world were evaluated in an experiment based on agro-morphological traits under two optimal and phosphorus deficient conditions in a completely randomized design with three replications in pots in 2017-18 cropping season. Based on results of descriptive statistics, the average of most studied traits was reduced in phosphorus deficient compared to optimal conditions, and the most damage caused by phosphorus deficiency were observed in plant phosphorus percentage, grain yield per plant and head and plant dried weights, respectively. In population structure analysis based on 128 IRAP and 120 REMAP markers, two sub-populations (K=2) were identified in association panel and amount of linkage disequilibrium for the retrotransposon based molecular markers was 3.4%. In association analysis using MLM model, 17 and 19 markers were identified for traits in optimal and phosphorus deficient conditions, respectively and the cfcr8-1 marker was common between traits in optimal and phosphorus deficient conditions. The results obtained from this study present valuable information on the genetic basis of studied traits that can be used for breeding and developing high performance varieties in sunflower.