【作者】 任仲海；

【导师】 林鸿宣；

【作者基本信息】 中国科学院研究生院（上海生命科学研究院） ， 遗传学， 2005， 博士

【摘要】 土壤盐渍化正越来越严重地威胁着水稻的产量,因此,了解水稻的耐盐机制,进而培育出耐盐的水稻品种,势在必行。我们利用著名的耐盐籼稻品种Nona与盐敏感的优质粳稻品种越光杂交得来的F2及相应的F3群体,进行QTL分析,定位到一些与水稻耐盐相关的QTLs。SKC1是一个与水稻地上部分K+浓度相关的主效QTL,它可以解释40.1%的K+浓度表型变异。我们利用以越光为轮回亲本的BC2F2群体中192个单株及其相应的BC2F3株系进行精细定位,将SKC1定位于STS标记K159与K061-2之间3.2 cM内,与CAPS标记K0625紧密连锁。利用标记K159与K061-2,从含有2973株的BC2F2或BC3F2群体中筛选出133个交换个体,从这133个株系挑选出30个株系,用BC2F4或BC3F4进行表型鉴定。经高精确度连锁分析,将SKC1限定于CAPS标记Pr和K036之间约7.4 kb内。该区域内只有一个候选基因,利用PCR技术从Nona的cDNA文库中获得SKC1的全长ORF。Blast分析表明SKC1属于HKT基因家属的新成员。序列分析显示SKC1基因由3个外显子和2个内含子构成,Nona和越光的SKC1有4个氨基酸的差异。我们利用Nona的启动子区加ORF成功地进行了遗传互补实验。启动子加GUS转基因水稻分析表明SKC1只在维管束中表达,主要集中在木质部周围的薄壁细胞。GUS以及RT-PCR分析显示SKC1在根部有较强的表达。同时,我们选育了含有5 cM Nona基因组片断的NIL(SKC1)(BC5F2)来研究SKC1的功能。在140 mM NaCl处理条件下,和轮回亲本越光相比,NIL(SKC1)地上部分能够保持更高的K~+和更低的Na~+;更多还原

【Abstract】 It is necessary to understand the mechanism of rice salt tolerance forimproving new salt tolerant rice variety, because soil salinity is more and moreseriously threatening rice production. An F2 and an equivalent F3 populationderived from a cross between a high salt-tolerance indica variety, Nona Bokra,and a susceptible elite japonica variety, Koshihikari, were produced. Weperformed QTL mapping for physiological traits related to rice salt-tolerance,and several QTLs were detected. Of these QTLs, a major QTL mapped on theshort arm of chromosome 1 with the very large effect, SKC1 for shoot K+concentration, explained 40.1% of the total phenotypic variance. The backcrosspopulations (Koshihikari was as the recurrent parent) was developed. Using 192lines from BC2F2 backcross population and their equivalent progeny BC2F3,fine mapping of SKC1 was performed. SKC1 was mapped in the 3.2 cM regionbetween the STS makers K159 and K061-2, and it was closely linked to theCAPS maker K0625. 133 lines with recombination between K159 and K061-2were screened from BC2F2 or BC3F2 population containing 2973 plants.High-resolution linkage analysis performed by using 30 BC2F4 or BC3F4 linesselected from those 133 lines enabled us to define a genomic region of ~7.4 kbas a candidate for SKC1. Only one candidate gene is in the region, and thefull-length ORF of SKC1 was obtained from the cDNA library of Nona by usingPCR. Blast analysis revealed that SKC1 is a homolog of HKT1 in Wheat.Sequencing analysis revealed 3 exons and 2 introns in SKC1 gene, and fouramino acids difference between NSKC1 from Nona and KSKC1 fromKoshihikari. Genetic complementation analysis proved the function of thecandidate gene by using promoter-ORF from Nona. Analysis of SKC1promoter-β-glucuronidase transgenic rice plants revealed expression of SKC1 invascular bundles, and mainly in parenchyma cells at the xylem. Analysis ofSKC1 promoter-β-glucuronidase and RT-PCR revealed strong expression ofSKC1 in root. A nearly isogenic line (NIL) of the target QTL, NIL (SKC1), inwhich a 5 cM chromosomal segment of Nona including SKC1 was substitutedinto the genetic background of Koshihikari, was selected based onmaker-assisted selection for studying the function of SKC1. Under 140 mMNaCl condition, NIL (SKC1) shoot could maintain more K+ and less Na+ thanthat of Koshihikari shoot. There also was higher K+ and less Na+ in the xylemsap of NIL (SKC1) plants exposed to 25 mM NaCl. Moreover, the salt toleranceof NIL (SKC1) plants was more slightly enhanced than that of Koshihikari undersalt stress. These results suggest that SKC1 play an important role in theprogress controlling long-distance K+ and Na+ transport from root to shoot.更多还原