利用染色体片段置换系定位低温胁迫下水稻根数QTL

Mapping QTLs Tolerant to Cold Stress in Rice Root by Chromosome Segment Substitution System

为解析低温胁迫水稻根数的遗传机理,挖掘控制水稻耐冷QTL,以亲本9311(受体)/日本晴(供体)构建的染色体片段置换系群体为材料,15℃处理10 d再在25℃恢复7 d测定其根数并定位和分析其中影响根数的QTL。结果显示,亲本日本晴平均根数为4.50,9311平均根数为7.20,二者存在显著差异;置换系群体平均根数为4.84,存在超亲分离现象。共检测到2个低温胁迫影响水稻根数的主效QTL:qCSRN1.1和qCSRN3。这2个QTL分别分布在水稻的第1号染色体31.75~33.15 Mb区间和第3号染色体32.2~32.7 Mb区间,其LOD值分别为4.91和2.86,分别解释表型变异的16.27%和9.06%,其中qCSRN1.1增效等位基因来自亲本日本晴,qCSRN3增效等位基因来自亲本9311。候选基因分析显示qCSRN1.1区间有138个候选基因,其中68个与蛋白合成相关,42个与酶合成相关,3个为转录因子;qCSRN3区间有88个候选基因,其中62个与蛋白合成相关,9个与酶合成相关,3个为转录因子。此外,还检测到2个上位性QTLs,分布在第1号和第9号染色体上,其上位性效应为-0.34和-0.43,LOD值为5.60和5.75。结果表明,低温胁迫下,水稻根数的发育属于数量性状,同时受基因互作影响。这些根数QTL的定位为后期克隆受低温胁迫影响的根数基因,解析根数遗传机理奠定了基础。

To analyze the genetic mechanism of rice root number under low temperature and detect the cold stress related QTL,a chromosome segment substitution line(CSSLs)population of japonica variety Nipponbare in the background of indica cultivar 9311 used as the materials.The CSSL lines were treated under 15℃for 10 days and then restore 7 days at 25℃temperature,the root number was measured and QTL for root number was detected.The result display Nipponbare average root number was 4.50;9311 average root number was 7.20.The two kind of rice variety had very difference obvious.CSSL lines average root number was 4.84 and exist transgressive segregation.A total of two major QTLs,qCSRN1.1 and qCSRN3,were detected for root number.The two QTLs were located 31.75-33.15 Mb on chromosome 1 and 32.2-32.7 Mb on chromsome 3,respectively.The LOD values of these QTLs were 4.91 and 2.86 respectively,and the phenotypic variation explained by these QTL were 16.27%and 9.06%,respectively.The positive allele of qCSRN1.1 was from Nipponbare while positive allele of qCSRN3 was from the 9311.Candidate gene analysis showed that there were 138 candidate genes in qCSRN1.1;68 genes were related to protein synthesis;42 genes were related to enzymatic synthesis;3 genes was transcription factor.qCSRN3 had 88 candidate genes;62 genes were related to protein synthesis;9 genes were related to enzymatic synthsis;3 genes was transcription factor.Furthermore,two QTLs epistatic QTLs were detected on chromosomes 1 and 9,their epistatic effected were-0.34 and-0.43;LOD values of these QTLs were 5.60 and 5.75.The results showed that in low temperature stress,the development of rice root number was quantitative trait and affected by QTL interaction.The localization of these root number QTLs laids a foundation for the cloning of root number genes and the analyzed of root number genetic mechanism under low temperature stress in future.