Identification of QTL Involved in Low-temperature Tolerance at The Germination Stage by Recombination Inbred Lines in Rice

Low-temperature germination (LTG) resistance of direct-seeded rice (DSR) seeds can overcome the developmental delay caused by low-temperature stress and ensure the vigorous growth of seedlings. The LTG is complex quantitative trait controlled by QTL s and has low genetic force, which leads to low efficiency of the direct selection of the trait by breeders. The research on QTL mapping for LTG in rice is helpful to carry out molecular marker-assisted selection (MAS) and improve the efficiency of selection for LTG in DSR breeding. In this study, the LTG rate showed extremely significant differences between the high-quality japonica rice variety Nanjing 46 in Jiangsu and the local variety Zhaxima in Yunnan. The QTL mapping was carried out by a recombination inbred line population (RIL) derived from a cross between Zhaxima and the Nanjing46. Total three QTL s ( qLTG-2 , qLTG-4 and qLTG-7 ) involved in LTG were detected on chromosome 2, 4 and 7, respectively. They accounted for 7.69%, 8.75% and 22.93% of the total phenotypic variation (PV), respectively. Interestingly, there was no reported QTL involved in LTG in the candidate region of qLTG-2 , which exhibited that the qLTG-2 was a novel QTL locus. The QTL s detected in this study will provide new genetic material and molecular markers for improving the low-temperature tolerance at germination stage in rice by molecular marker assisted selection breeding.