水稻高秆染色体片段代换系Z1377的鉴定及重要农艺性状QTL定位

株高是水稻重要的农艺性状, 往往与产量相关性状密切关联, 在水稻育种中有重要利用价值。本研究以日本晴为受体、缙恢35为供体亲本, 经表型和分子标记双重选择, 鉴定了一个水稻高秆染色体片段代换系Z1377。Z1377共含有18个代换片段, 平均代换长度为2.95 Mb。与日本晴相比, Z1377的株高、倒一节间至倒四节间长、穗长、一次枝梗数、二次枝梗数、粒长、每穗实粒数、总粒数显著增加; 粒宽显著变细, 有效穗数、结实率显著减少, 但仍达86.75%。用日本晴与Z1377杂交构建的次级F₂群体共检测到16个相关QTL, 分布于第2、第3、第4、第5、第6、第7和第9染色体。其中有8个可能与已克隆基因等位, 如GW2、EUI1、ZFP185等, 另8个如qPH3等尚未见报道。Z1377的株高由一个主效QTL (qPH3)和一个微效QTL (qPH5)控制, 其中qPH3的贡献率达28.59%。而且, 在F₂群体中, 高秆和矮秆基本呈现双峰分布, 经卡平方测验, 符合3∶1分离比, 表明高秆对矮秆显性, 并主要由qPH3负责。这将为该主效基因的精细定位和克隆奠定基础, 同时为进一步选育含2~3个代换片段的中高优良染色体片段代换系并应用于育种奠定基础。

Identification of Rice Chromosome Segment Substitution Line Z1377 with Increased Plant Height and QTL Mapping for Agronomic Important Traits

Plant height is an important agronomic trait in rice, usually relating to yield-related traits. Here, a novel rice chromosome segment substitution line Z1377 with increased plant height was identified from recipient Nipponbare and donor Jinhui 35 through selection of both phenotype and molecular marker. Z1377 carried 18 substitution segments with average substitution length of 2.95 Mb. Compared with Nipponbare, Z1377 had significantly increased plant height, length of the 1st, 2nd, 3rd, and 4th internode, panicle length, number of primary and secondary branches and grain length, and decreased grain width, number of panicles per plant and seed setting ratio. However, the seed setting ratio was still 86.75%. Furthermore, F₂ population from crosses between Nipponbare and Z1377 was used to map QTLs for plant height and other important agronomic traits. A total of 16 QTLs were detected, of which eight had been reported with the cloned genes such as GW2, EUI1, ZFP185, and the other eight were still not reported, such as qPH3. The plant height of Z1377 was mainly controlled by a major QTL (qPH3) with the explained phenotypic variance of 28.59% and a minor QTL (qPH5). Moreover, the high and dwarf plants basically displayed a bimodal distribution in the F₂ population, and fitted to 3:1 segregation ratio by Chi-square test, indicating that high plant is dominant to dwarf plants and mainly conferred by qPH3. These results lay a foundation for fine mapping and cloning qPH3, meanwhile, also provide good bases for developing excellent chromosome segment substitution lines with moderate height plant carrying 2-3 substitution segments to be used in breeding.