Genetic analysis and QTL mapping of agro-morphological traits in sunflower (Helianthus annuus L.) under two contrasting water treatment conditions

The present study was undertaken to investigate the genetic basis and map quantitative trait loci (QTLs), controlling agronomic traits in sunflower under well-watered and water-stressed conditions. Recombinant inbred lines (RILs) coming from the cross between sunflower parental lines PAC2 and RHA266 were evaluated in a rectangular 8x9 lattice design with two replications in each treatment conditions. High genetic variability and transgressive segregation was observed for all studied traits in both water treatment conditions. Significant correlations were observed among studied traits. QTL-mapping was performed using a recently developed SSR sunflower linkage map. One to eleven QTLs were found for studied trait across two water treatment conditions. The percentage of phenotypic variance (R-2) explained by QTLs ranged from 0.23 to 48.89%. Based on overlapping support intervals, the co-location of QTLs for studied traits was determined. QTLs controlling most of the traits were overlapped on different linkage groups, which was in accordance with the phenotypic correlation results among the traits. A comparative analysis of identified QTLs herein with those described in previous studies for drought adaptive traits revealed a number of QTLs in common. These QTLs have potential use in marker-assisted selection.