摘要
Many important agronomic traits, including cold stress resistance, are complex and controlled by quantitative trait loci （QTLs）. Isolation of these QTLs will greatly benefit the agricultural industry but it is a challenging task. This study explored an integrated strategy by combining microarray with QTL-mapping in order to identify cold-tolerant QTLs from a cold-tolerant variety ILl12 at early-seedling stage. All the early seedlings of IL112 survived normally for 9 d at 4-5℃, while Guichao2 （GC2）, an indica cultivar, died after 4 d under the same conditions. Using the F2-3 population derived from the progeny of GC2 and ILl12, we identified seven QTLs for cold tolerance. Furthermore, we performed Affymetrix rice whole-genome array hybridization and obtained the expression profiles of ILl12 and GC2 under both low-temperature and normal conditions. Four genes were selected as cold QTL-related candidates, based on microarray data mining and QTL-mapping. One candidate gene, LOC_Os07g22494, was shown to be highly associated with cold tolerance in a number of rice varieties and in the F2-3 population, and its overexpression transgenic rice plants displayed strong tolerance to low temperature at early-seedling stage. The results indicated that overexpression of this gene （LOC_Os07g22494） could increase cold tolerance in rice seedlings. Therefore, this study provides a promising strategy for identifying candidate genes in defined QTL regions.
Many important agronomic traits, including cold stress resistance, are complex and controlled by quantitative trait loci （QTLs）. Isolation of these QTLs will greatly benefit the agricultural industry but it is a challenging task. This study explored an integrated strategy by combining microarray with QTL-mapping in order to identify cold-tolerant QTLs from a cold-tolerant variety ILl12 at early-seedling stage. All the early seedlings of IL112 survived normally for 9 d at 4-5℃, while Guichao2 （GC2）, an indica cultivar, died after 4 d under the same conditions. Using the F2-3 population derived from the progeny of GC2 and ILl12, we identified seven QTLs for cold tolerance. Furthermore, we performed Affymetrix rice whole-genome array hybridization and obtained the expression profiles of ILl12 and GC2 under both low-temperature and normal conditions. Four genes were selected as cold QTL-related candidates, based on microarray data mining and QTL-mapping. One candidate gene, LOC_Os07g22494, was shown to be highly associated with cold tolerance in a number of rice varieties and in the F2-3 population, and its overexpression transgenic rice plants displayed strong tolerance to low temperature at early-seedling stage. The results indicated that overexpression of this gene （LOC_Os07g22494） could increase cold tolerance in rice seedlings. Therefore, this study provides a promising strategy for identifying candidate genes in defined QTL regions.
基金
This research was supported by the National Natural Science Foundation （Grant No. 30971755）
Ministry of Agriculture of China （Grant No. 2009ZX08009-106B）, Self-Regulated Projects of State Key Laboratory of Plant Physiology and Biochemistry, and Chang Jiang Scholars Program.The authors thank Ms Hong Yan （China Agricultural University） and Ms Zhuo Xing （Chinese Academy of Sciences） for their kind assistance in the GeneChip and qRT-PCR operations. We also thank Professor Daoxin Xie （Tsinghua University, China） and Professor Zhizhong Gong （China Agricultural University） for pre-reviewing the paper and for their helpful suggestions. No conflict of interest declared.
