Mapping QTLs Controlling Drought Tolerance Indices in Sunflower (Helianthus annus L.)

Drought stress is an important limiting factor for plant growth. Using selection indices, it is possible to identify cultivars with high yield in normal and stressed conditions. So, the genetic analysis of drought tolerance indices can play important role in plant breeding programs. In order to identify molecular markers linked with drought tolerance indices in sunflower, 72 recombinant inbred lines produced from a cross between RHA266 and PAC2 lines, were evaluated in 8×9 rectangular lattice design with two replications in normal and water-stressed in field conditions. Based on bi-plot produced from the principal component analysis, high genetic variability was observed among studied lines. Among the studied indices, a significant positive correlation was seen between GMP, MP, HM, YJ and SVI indices with seed yield in both normal (Yp) and water-stressed (Ys) conditions. Using composite interval mapping, 32 QTLs were detected for studied drought tolerance indices. Results showed that the identified QTLs for YI, MP, GMP indices in linkage groups 13 were co-localized with QTLs reported for sunflower yield. Therefore, it is possible to use GMP, MP and YI as the most appropriate indices for selection of drought tolerant lines in sunflower.