Genetic basis of drought tolerance in Iranian rice (Oryza sativa ) recombinant lines at vegetative and reproductive stages

To evaluate the genetic basis of drought tolerance in rice, an experiment was conducted using 120 recombinant inbred lines (RILs) derived from Neda × Ahlamitarom cross. A factorial experiment based on completely randomized design with three replications was used under greenhouse conditions setting at Gonbad Kavous University. In this study, Polyethylene Glycol (PEG) 6000 was employed to induce osmotic stress (at levels of −4.5 and −9 bar) during both vegetative and reproductive stages. In addition to assessing root and shoot morphological characters, genetic linkage map was constructed using Simple Sequence Repeat (SSR), Inter Primer Binding Site (iPBS), Inter-Retrotransposon Amplified Polymorphism (IRAP), and Inter Simple Sequence Repeats (ISSR) markers. Sixteen Quantitative Trait Loci (QTLs) were identified during vegetative growth stage, while twenty QTLs were identified during the reproductive stage. Through a comparative analysis of the three evaluated treatments, the qRN-12, qRS-11, and qRV-12 lines were determined as stable QTLs  suitable for the selection of drought-tolerant lines at the vegetative stage under varying conditions. Several new alleles associated with drought-tolerant QTLs were identified in this study. Notably, in two distinct environmental conditions, crucial QTLs, such as qNTF-12 and qNL-3, related to the numbers of fertile tillers and leaves, were identified as stable QTLs at the reproductive stage. The QTLs identified at vegetative and reproductive stages in this study can serve as stable and major QTLs for  selecting drought-tolerant lines in marker-assisted selection (MAS).