Physiological aspects of inter-specific gene introgression to improve drought tolerance in safflower

Abstract

Wild introgression may play an important role to improve drought tolerance of safflower (Carthamus tinctorius L.). Response of populations derived from inter-specific hybridization to drought stress in terms of physiological traits and the possibility of selection of superior lines are poorly understood in safflower. Inter-specific hybridizations were performed to produce three populations of TP (C. tinctorius × C. palaestinus), PO (C. palaestinus × C. oxyacanthus), and TO (C. tinctorius × C. oxyacanthus). In total, a number of 189 lines derived from hybridization along with their parents were evaluated in the field in F3 (2015), F4 (2016) and F5 (2017) generations under normal and drought stress conditions. The results indicated that under drought stress condition, C. tinctorius and C. palaestinus had higher malondialdehyde and proline content, while the highest relative water content was belonged to C. oxyacanthus. Consequently, various inter-specific populations behaved differently to decrease the effect of drought stress. TP and TO with C. tinctorius as their common parent, had higher seed yield and seed yield component than PO population. TP population was the most tolerant population due to its highest stress tolerance index, while TO population showed the highest seed yield stability under deficit irrigation. The results indicated that gene introgression from wild relatives into cultivated safflower gene pool increased genetic variation and provided the chance of selection of superior drought tolerant genotypes for future breeding programs.