水稻苗期耐盐基因qSTS8的精细定位与候选基因分析

Soil salinity is a major abiotic stress harmful to rice production. As a common phenomenon in Ningxia, salinization has caused soil degradation and a prominent reduction of rice yield. In our previous study, an F2 population derived from a cross between a salt-tolerant rice variety, Faguodao, and a salt-sensitive rice variety, Nipponbare, was produced. Further genome-wide analysis of the linkage map constructed from the F2 population showed that a major salt-tolerant QTL, designated qSTS8, was detected on chromosomes 8 and the contribution rate to the total phenotypic variance reached to 22 %. In this project an advanced backcross and consecutive molecular marker-assisted selection strategy will be used to develop a BC3F2 population, which derived from salt-tolerant F3 lines, as the donor, and salt-sensitive parent Nipponbare, as the recipient with the aim of fine mapping of qSTS8. The whole genome expression profiles between salt-tolerant near-isogenic line (FSTS8) and Nipponbare under salt stress or normal growth conditions will be analyzed using RNA-seq technique. The SNP (Single nucleotide polymerase) difference in gene region will then be identified following screening the differential expression genes (DEGs). According to the data integrated from QTL region, DEGs and SNP information, the candidate gene associated with salt tolerance will be screened. Meanwhile, the sequence of the candidate gene in rice germplasm resources will be analyzed systematically and then their functional mutational-sites will be determined using the association analysis. Eventually, genetic effects of different alleles will be analyzed, and genes with potential beneficial value will be explored. The results will give important reference for studies of molecular mechanisms of salt-tolerance in rice, and to provide theoretical support for rice breeding for salt tolerance using molecular methods.

土壤盐渍化是危害水稻生产的重要非生物胁迫之一。宁夏土壤盐渍化非常严重，水稻生产受其影响极为明显。申请人利用耐盐品种“法国稻”和盐敏感品种“日本晴”杂交获得的F2群体在水稻8号染色体定位了1个新的耐盐相关主效QTL qSTS8，贡献率22%。本项目拟利用耐盐F3家系与日本晴连续回交，结合分子标记辅助选择获得BC3F2群体，采用染色体代换定位策略，对该位点进行精细定位。利用转录组测序分析盐胁迫和正常生长条件下日本晴和耐盐近等基因系NIL（FSTS8）的全基因组表达谱，筛选差异表达基因、鉴定基因区SNP差异。将精细定位区间与基因组表达谱和SNP信息整合，筛选耐盐候选基因。系统测定水稻种质资源耐盐候选基因序列，利用关联分析方法，确定功能性突变位点，发掘具有潜在利用价值的有利等位基因。本项目研究结果不仅为水稻耐盐分子机理研究提供重要参考，而且为利用分子育种途径提高水稻品种耐盐性提供理论支持。

土壤盐渍化是危害水稻生产的重要非生物胁迫之一。宁夏土壤盐渍化非常严重，水稻生产受其影响极为明显。本研究利用法国稻和日本晴的耐盐F3家系与日本晴连续回交2代获得的BC2F2次级定位群体将qSTS8定位区间缩小到1个366Kb的区间内；利用BC3F2群体进行交换单株筛选和表型评价，采用染色体片段代换定位策略，最终将水稻苗期耐盐基因qSTS8精细定位到水稻8号染色体长臂端Indel标记MK8和SSR标记OSSR8之间1个30Kb区间内，包含3个预测基因。结合盐胁迫和正常生长条件下日本晴和耐盐近等基因系NIL（FSTS8）的转录组测序结果，将精细定位区间与基因组表达谱和SNP信息整合，通过对区间内3个预测基因两亲本的测序分析，结合基于候选基因的关联分析，发现预测基因1的编码区在两亲本间有1个12bp的Indel，编码蛋白质结构发生了很大变化；预测基因2两亲本之间存在3个SNP和2个单碱基Indel，盐胁迫后，两亲本该基因表达量有明显差异；预测基因3在两亲本间无差异；最终确定预测基因1和2为耐盐候选基因，发现了2个功能性突变位点，发掘了具有潜在利用价值的有利基因。本项目研究结果不仅为水稻耐盐分子机理研究提供重要参考，而且为利用分子育种途径提高水稻品种耐盐性提供理论支持。