稻米外观和碾磨品质QTL定位及其与土壤水分环境互作分析

本文利用旱稻品种IRAT109和水稻品种越富的花培DH群体的116个株系为作图群体，采用混合线性模型QTL定位方法，在水、旱2个土壤水分环境下对粒长(GL)、粒宽(GB)、长宽比(LWR)和垩白率(C)4项外观品质性状和糙米率(BR)、精米率(MR)、整精米率(HR)3项碾磨品质性状进行QTL定位及QTL与环境互作分析。在水、旱2种条件下对DH群体差异显著性分析结果表明，糙米率、精米率和长宽比差异不显著,而整精米率、粒长、粒宽、垩白率差异极显著。外观品质性状在水、旱栽培条件下变化较大，即在旱种环境下稻米粒形变小（粒长、粒宽减小）、变细（长宽比增大）垩白率大幅度下降。碾磨品质性状在双亲间均有差异，其中整精米率差异较大；且在两种土壤水分环境条件下均有变化，即在旱栽条件下两亲本的糙米率和精米率均降低，IRAT109分别减少了5.8%和5.5%，越富分别减少了11.7%和11.5%。共检测到11个加性效应QTL与稻米外观和碾磨品质性状7项指标有关，分别位于第1、3、5、6、7、10、11染色体上，单个QTL对性状的贡献率在3.15～21.42%之间，位于第1、7 染色体上2个控制整精米率的QTL存在显著环境互作，单个QTL与环境互作效应的贡献率分别为9.59%和13.58%。在第1染色体RM295标记附近同时检测到5个QTL，Qgc1a 、Qgc1b 、Qlwr1、QMr1b和QHr1，分别控制粒长、长宽比、精米率和整精米率，且该QTLs簇在2个环境下能稳定地被检测到。同时，还检测到10对上位性QTLs，所有上位性QTL都发生在不同染色体之间，其中，控制整精米率的4对QTL与土壤水分环境显著互作，其环境互作贡献率分别为14.29%、12.28%、10.56%和13.47%。控制粒长、粒宽、长宽比的6个加性QTL（Qgc1a、Qgc1b、Qgc5、Qgw6、Qlwr1、Qlwr10）与环境之间互作较小，在品质育种中可利用分子标记对其进行辅助选择，提高育种效率；而对于基因型×环境互作效应大的整精米率、垩白率应在特定环境(如土壤缺水条件)下进行选择，在特定水分胁迫条件选择目标亲本，并将抗旱基因导入该亲本方可选到品质较优的抗旱品种。

QTL Mapping and QTL×Environments Interactions of Grain Milling and Appearance Quality Traits in Rice under Upland and Lowland Environments

To reveal the differentiation of phenotypic values and QTLs for grain quality traits in rice, we evaluated a doubled haploid (DH) population from a cross between two japonica cultivars for milling quality traits including brown rice (BR), milled rice (MR) and head milled rice (HR) and grain appearance traits including grain length (GL), grain breadth (GB), grain length- breadth ratio (LWR), and chalkiness (C) cultivated under upland and lowland environments. The analysis of variance (ANOVA) between upland and lowland environments for all the traits showed that HR, GL, GB and C were more easily influenced by environment than BR, MR and LWR. The values of BR, MR and HR of the lowland parent Yuefu were higher than that of the upland parent IRAT109 under lowland environment. But under upland environment, the BR and MR for the parents were both declined by 5.8% and 5.5% for IRAT109，and 11.7% and 11.5% for Yuefu respectively. The values of GL, GB and C were all reduced under upland condition than that under lowland condition for all the two parents while the value of LWR had the opposite tendency. Compared to lowland environment, some quality traits changed such as an increased HR, decreased C, and thinner grain shape when cultivated under upland environment. Using a complete genetic linkage map with 165 molecular markers covering 1535 cM, QTLs for these traits were mapped under upland and lowland environments. A total of eleven additive QTLs and ten pairs of epistatic QTLs associated with BR, MR, HR, GL, GB, LWR, and C were detected. It was found that epistasis was an important genetic component underlying BR, MR, HR and C. The result also showed that MR, GL, GB and LWR were less affected by upland environment. However, HR was affected greatly by upland environment. Four intervals on chromosomes 1, 3, 6 and 7 were found to contain multiple QTLs(co-localization). Eight common QTLs for these traits across different studies were also revealed. These co-localized QTLs and common QTLs will facilitate marker- assisted selection for grain quality traits in rice breeding.