氮胁迫和正常条件下玉米穗部性状的QTL分析

QTL Mapping of Ear Traits under Low and High Nitrogen Conditions in Maize

【目的】分析氮胁迫和正常条件下玉米穗部性状的QTL。【方法】以优良玉米杂交种"农大108"的一套203个F2:3家系为材料,构建了包含189个SSR标记的遗传连锁图谱,在施氮(N+)和不施氮(N-)条件下,通过一年两点的田间试验,利用复合区间作图法对玉米穗长、穗粗、穗行数、行粒数、穗粒重和百粒重等6个穗部性状进行了QTL分析。【结果】亲本许178对N胁迫的敏感程度远小于黄C;F2:3群体的穗长、穗粗、穗行数和行粒数与单株产量大多呈显著或极显著正相关。在郑州和新郑两地,2种氮处理水平下定位了玉米穗部性状的53个QTL,其中郑州点检测到28个QTL,主要集中在第2、8和9染色体上(占57.14%);新郑点检测到25个QTL,主要分布在第1、2、6、7和8染色体上(占60%);在所检测到的53个QTL中,表现加性、部分显性、显性和超显性效应的QTL依次为13(24.5%)、20(37.7%)、6(11.3%)和14(26.4%)个,单个QTL解释表型变异介于7.1%～23.3%之间。N+条件下6个性状在两个地间检测到的QTL数量明显高于N-条件下检测到的QTL数量,同时在郑州点2种氮处理水平下检测到3个相同的QTL(qED2a,qKW8a,qKW10a),新郑点检测到1个相同的QTL(qEL1a),推断在缺氮条件下检测到的各性状特异表达的QTL可能与玉米的氮高效利用有关。【结论】在两地、2种供氮水平下所定位的53个穗部性状QTL,主要集中在第1、2、8和9染色体上,部分显性和超显性效应的QTL占60%以上。

[ Objective ]The purpose of this study was to analyze the QTL of ear traits under low and high nitrogen conditions in maize. [Method] In this investigation, six ear related traits including ear length （EL）, ear diameter （ED）, row number （RN）, kernel number per row （KN）, grain yield per ear （GY） and 100 kernel weight （KW）, were investigated using a set of 203 F2. 3 population, which derived from an elite hybrid maize Nongda 108 （Huang C X Xu 178）. The F2：3 population were evaluated under high （N＋） and low （N-） nitrogen conditions in Zhengzhou and Xinzheng in 2004, and the genetic linkage maps were constructed including 189 SSR markers. [Result] N- stress had more influence to the parent Huang C than to the parent Xu 178, and the EL, ED, RN and KN had mainly significant/highly significant positive correlation with GY. A total of 53 QTL were identified under N＋ and N- conditions in two locations using the composite interval mapping method, including 28 QTL detected in Zhengzhou and 25 QTL detected in Xinzheng. Many QTL detected in Zhengzhou located on chromosome 2, 8 and 9（occupied by 57.1%）, and the QTL identified in Xinzheng mainly clustered in chromosome l, 2, 6, 7 and 8 （occupied by 60.0%）. Out of the 53 QTL, 13 QTL appeared to have the additive effect, 20 QTL exhibited partial dominant effect, 6 QTL expressed dominant effect and 14 QTL exhibited over-dominant effect, and the phenotypic variance explained by single QTL varied from 7.1% to 23.3%. The QTL detected for the six measured traits under N＋ condition in two locations were more than the QTL identified under N- condition, and there were 3 and 1 QTL detected under the two nitrogen levels in Zhengzhou and Xinzheng simultaneously. These results implied that the QTL detected for the measured traits only under low nitrogen stress might be related with nitrogen high use efficiency in maize. [Conclusion] The 53 QTL identified mainly clustered in chromosome 1, 2, 8 and 9, over 60% QTL appeared to be partial dominant and over-dominant effect.