Pyramiding of rapid germination loci from Oryza Sativa cultivar ‘Xieqingzao B’ and cold tolerance loci from Dongxiang wild rice to increase climate resilience of cultivated rice

Rapid and uniform germination of seeds and subsequent high survivability of seedlings in low-temperature environments are two key requirements in the direct-seeding agronomic production system in rice. Dongxiang wild rice (DXWR), the northernmost common wild rice, possesses a number of seedling cold-tolerance loci and is an invaluable genetic resource for the molecular breeding of cold-tolerant rice. However, DXWR has a delayed and desynchronized germination trait in low-temperature environments that is favorable for its adaption to cold environments but is a disadvantage for seedling establishment in the direct-seeding system when integrated into elite cultivars. In the present study, we identified five quantitative trait loci (QTLs) for low-temperature germination in DXWR. All the DXWR alleles delay the germination of DXWR seeds in low-temperature environments. By the pyramiding of QTLs of rapid germination from cultivated rice and QTLs of seedling cold tolerance from high tolerance wild rice DXWR, we obtained a variety numbered DX71 with rapid and uniform germination of seeds and high cold tolerance of seedlings in low-temperature environments. The results could facilitate the understanding of the genetic basis of delayed germination in DXWR, partly explaining how DXWR adapts to low temperatures in its habitat. The identified QTLs provide tightly linked markers for rice breeding in the development of climate-resilient varieties with low input.