Identifying genetic resources and QTL for cold tolerance in rice

Low temperature is a common production constraint in rice cultivation in Australia and many other temperate countries. To improve the cold tolerance of rice varieties, we have evaluated the cold tolerance of 17 rice varieties from different countries at germination, seedling, booting and flowering stages. Three varieties from China (B55, Lijianghegu, Banjiemang) and one from Hungary (HSC55) showed consistent tolerance to low temperature at all growth stages. These varieties are potentially important gene donors for breeding and genetic studies. Australian variety Amaroo is tolerant to low temperature at the seedling stage, while Quest is tolerant at seedling and flowering stages. The cold tolerance of the 17 rice varieties assessed at different growth stages was correlated. Based on the cold tolerance of the varieties at different growth stages, variety Reiziq was crossed with Lijianghegu. The F2 and BC1F1 populations were developed for QTL mapping. Among the screened 373 SSR and 325 STS primers, 53 SSR (15%) and 36 STS (11%) primers showed polymorphism between RZQ and LJHG. One QTL (qCTB-10-2a) was identified to be associated with cold tolerance at booting stage on short arm of chromosome 10. The QTL could explain 20.5% of the total genetic variation with -14.4% addictive and 7.5% dominant effect for spikelet fertility after low temperature treatment