玉米株型相关的耐旱基因/QTL定位及位点互作效应研究

Maize architecture traits are closely related to drought tolerance. Compared with flat plant type maize, compact plant type maize has stronger drought tolerance. So, it is of great significance to study drought tolerance mechanism of compact plant type maize and to map plant-type traits related gene/QTL for cultivating compact plant-type maize varieties and reducing drought loss. In this study two F2:3 populations derived from Langhuang×TS141 and Chang7-2× TS141 will be used to detect drought tolerant QTLs related to maize architecture traits(such as leaf angle, leaf orientation value, leaf shape value) under different water regimes in the bell-mouthed period when maize is most sensitive to drought tolerance in Wuwei Gansu province by stepwise joint QTL mapping method. These QTLs in this study will be integrated into informations of the published QTLs relevant to maize plant type, and drought tolerant MQTL related to plant type will be mapped through the Meta-QTL analysis; at the same time, candidate genes relevant to maize plant type will be speculated which are located on MQTL regions through comparative genomics and bioinformatics. Then, we will study interaction effect between MQTLs sites controlling drought tolerance related to maize architecture traits by the means of building near isogenic lines. Combining MQTL, drought tolerant QTLs to control maize architecture traits will be finely mapped by the means of building fine mapping groups. The results will provide theoretical foundation for cloning candidate genes studying molecular mechanism of drought tolerance in compact plant type maize.

玉米的株型性状与耐旱性关系密切，紧凑株型玉米与平展株型相比有较强的耐旱性。因此研究紧凑株型玉米的耐旱机理，定位株型相关的耐旱基因/QTL，对培育紧凑株型玉米新品种、减少干旱造成的损失具有重要意义。本研究以玉米自交系廊黄和昌7-2分别与TS141组配构建的两个F2:3群体为材料，采用逐步联合的QTL定位方法，在对干旱胁迫最敏感的大喇叭口期检测株型相关（叶夹角、叶向值、叶形值）的耐旱QTL。将QTL信息整合，获得株型相关的耐旱QTL的一致性区间(MQTL)；同时预测MQTL所在染色体区段的候选基因。构建近等基因系研究株型相关的耐旱MQTL位点之间的互作；利用精细定位群体对控制玉米株型相关的耐旱QTLs精细定位。这些结果将为候选基因的克隆和紧凑株型玉米耐旱性分子机理的研究提供理论基础。

玉米的株型性状与耐旱性关系密切，紧凑株型玉米与平展株型玉米相比具有较强的耐旱性，因此研究紧凑株型玉米的耐旱机理，定位株型相关的耐旱基因/QTL，对培育紧凑株型玉米新品种、减少干旱造成的损失具有重要意义。本研究以廊黄和昌7-2 分别与TS141组配构建2套F2:3群体，在多水分处理下，检测株型相关性状QTL位点、QTL与环境互作和上位性效应；采用生物信息学手段，构建玉米株型相关性状QTL“一致性”图谱，挖掘Meta-QTLs（MQTLs），预测候选功能基因；构建BC3F2群体对主要株型QTL进行精细定位、分析候选基因的基因网络。本研究取得的主要研究结果：.（1）亲本SSRs标记筛选及图谱构建.玉米基因组数据库网站（http://www.Maize GDB. org/）下载分布于玉米10条染色体的872对SSRs标记，上海Sangon公司合成，进行PCR扩增，在廊黄与TS141间获得多态性SSRs 213对。在昌7-2与TS141间获得多态性SSRs 217对。以廊黄与TS141杂交的F2分离群体和昌7-2与TS141杂交的F2分离群体构建2套遗传连锁图谱，前者图谱共199个标记，全长1542.5cM。后者图谱共205个标记，全长1648.8 cM。.（2）F2:3家系株型表现及QTL检测.2套F2:3家系，在不同控水处理下对株型进行多点鉴定。结果表明，干旱胁迫后，两套F2:3家系及其亲本的叶夹角、叶长、叶宽呈减少趋势，而叶向值呈增加趋势，表明玉米株型对干旱胁迫具有一定的调节能力，从而增强玉米对干旱胁迫的适应能力；两套F2:3家系的4个株型性状广义遗传力都较大，说明两套F2:3家系的四个性状的变异主要来源于其本身的遗传变异。采用复合区间作图法（CIM），在2套F2:3家系中总共检测到72个株型相关性状QTLs位点；采用基于线性模型的复合区间作图法（MCIM），在2套F2:3家系中总共检测到33个QTLs，7个QTLs与环境互作，11对QTLs存在AA上位性互作；确定了qLA-Ch.7-1为调控叶夹角的主效QTL。.（3）MQTLs定位、候选基因挖掘.采用生物信息学手段，构建了玉米株型性状“一致性”图谱（358个标记、全长6737.43 cM），挖掘出13个株型性状MQTLs和14个候选基因，这为玉米株型相关性状QTL的精细定位、图位克隆及分子标记辅助选择育种奠定基础。