Identification of QTLs controlling yield and yield components in sunflower under salinity stress conditions

Salinity stress is one of the most important abiotic stresses which threaten plants. In order to study the effect of salinity stress on yield and yield components of sunflower and also genetic analysis of these traits in relation with salt tolerance, a factorial experiment based on a completely randomized design with three replications was conducted. Pots were arranged outside the greenhouse in an open air area under natural environmental conditions. The studied factors were 2 salinity stress levels (normal and 6 dS/m) and sunflower recombinant inbred lines (102 lines derived from the cross PAC2 ×RHA266 together with parental lines). Results showed the significant effect of salinity stress on all of studied traits except petiole length, leaf width, leaf length, head diameter and seed weight, meanwhile, the effect of genotype was significant on all of the studied traits. Genetic analysis of measured traits was done using a linkage map with 221 molecular markers (210SSR/11SNP) with an average distance of 7.44 cM between markers via composite interval mapping (CIM). 14 and 17 QTLs were detected for studied traits under normal and salt stress conditions, respectively. The maximum amount of R2 (39.7%) was detected for QTL identified for days to flowering in salinity stress conditions. The results showed the existence of co-localized QTLs for some of the studied traits under normal and salt stress conditions. Using co-localized QTLs improve the efficiency of marker-assisted selection in plant breeding programs.