【作者】 郑建敏；

【导师】 郑家奎；

【作者基本信息】 重庆大学 ， 作物遗传育种， 2010， 硕士

【摘要】 杂种优势在杂交水稻中的应用已经取得了重大进展,然而许多杂交组合生育后期容易出现叶片过早衰老现象,造成空秕率高,影响到杂交稻产量潜力的发挥。为明确早衰机理及其调控机制,本实验针对一航天育种衰老突变体材料进行形态特征观察、农艺性状考察和突变基因定位研究,为进一步的基因克隆和基因功能研究工作奠定基础。研究结果如下:①突变体早衰特征观察和农艺性状考察突变体在移栽后约30天开始表现出衰老症状,从此时开始,新叶叶心抽出时,生长到定长的倒4叶片就开始变黄衰老,每个分蘖叶片的表现均类似;至抽穗开始时倒3叶片就开始变黄衰老;抽穗后期倒2叶衰老;灌浆后期剑叶即表现衰老,至种子完全成熟时剑叶已枯亡,叶片自叶心抽出至完全枯死大约经历15-20d,而野生型品种泸恢103在相同条件下可以保持25-30 d的绿色,成熟时叶片转色正常,符合水稻自然衰老的规律。单叶衰老过程由叶尖黄化向叶鞘逐渐进行。考察农艺性状表明,早衰突变体与野生型相比,穗长变短、千粒重下降,而株高和穗粒数显著降低,结实率和单株产量下降更为明显。②突变体遗传分析与基因定位为研究psl2的遗传规律,将psl2与R527进行杂交,对其F1与F2代进行性状分析,结果显示F2代中正常个体与早衰个体的分离比例符合3:1,表明该突变由一隐性等位基因控制。利用分布于水稻12条染色体上的537个SSR标记初步将目的基因定位在第3号染色体上,与标记RM251、RM282连锁。进一步寻找引物,最终将目的基因定位在分子标记RM14704与RM14710之间,距两标记间的遗传距离分别为0.1155cM、0.1540cM,物理区间约为370kb,采用Genescan软件进行候选基因预测,得到55个候选基因。更多还原

【Abstract】 Heterosis has been successfully used in hybrid rice for many years. There are many crosses of hybrid rice displaying premature senescence phenomenon on the leaves during late growth stage. It leads to the high rate of empty husks and affects yield potentiality of hybrid rice. In order to clarify the mechanism and regulation of early senescence, we studyed the phenotypes of a senescence mutant (psl2) by aeronautics in rice, and also used a map-based cloning strategy to locate psl2 gene.The results were as follows:①The investigation of premature senescence symptom and agronomic characters of the psl2 mutantAbout 30 days after transplanting, psl2 mutant began to appear senescent symptom. From that time on, a new leaf came out, then the top fourth leaf began to turn yellow, the performance of each leaf was similar. At the beginning of heading date, the top third leaf started to turn yellow. At the late stage of heading, the top second leaf started to senesce. Until the late filling stage, the flag leaf came into senescing. In yellow ripeness stage, all the leaves dried out. The average longevity of a leaf was about 15-20d in the psl2 mutant, while the wild-type varieties Luhui 103 could maintain 25-30 d under the same conditions. Each single leaf aged from the sheath. The status of the agronomy showed that, compared to the wild-type varieties Luhui 103,the spike length of psl2 mutant became shorter, the grain weight decreased, while height and grains per spike was significantly reduced and yield markedly declined.②Genetic analysis and Mapping of psl2 mutantIn order to determine the inheritance mode of the mutation, we made a cross between the psl2 and R527. All the F1 plants displayed wild-type phenotype, while the F2 progenies segregated in a ratio of 3:1(normal leaf : premature senescence leaf),indicating that a single recessive nuclear gene controls the mutant phenotype. Using 537 SSR markers which distributed on the 12 chromosomes of rice, the psl2 gene was initially located on the chromosome 3, linked with markers RM251 and RM282 .Further searching for primers, the objective gene was flanked by markers RM14704 and RM14710 at 0.1155cM and 0.1540cM intervals, respectively, with the corresponding distance of 370kb.Gen prediction indicated that there were 55 candidate genes.更多还原