多环境下玉米株高和穗位高的QTL定位

【目的】通过对玉米株高和穗位高进行多环境的QTL分析,寻找能够稳定表达的株高和穗位高主效QTL,以为玉米理想株型的分子育种提供理论依据。【方法】以优良玉米自交系许178×K12衍生的150个F7代重组自交系(recombinant inbred lines,RILs)群体为试验材料。首先,从Maize GDB中选取495个SSR标记进行亲本间多态性筛选,利用具有多态性的标记进行群体基因型分析,使用Map Maker V3.0软件划分标记的连锁群并构建遗传连锁图谱。其次,采用Ici Mapping V4.0软件的完备区间作图法(inclusive composite interval mapping,ICIM)进行2年3点(陕西榆林、陕西杨凌、辽宁葫芦岛,2014—2015年)表型值及育种值的株高和穗位高QTL分析。最后,对株高和穗位高进行条件QTL分析,对照非条件QTL分析的结果,探讨株高和穗位高在QTL水平上的遗传关系。【结果】构建的遗传连锁图谱共包含191个SSR标记,图谱全长2 069.1 c M,平均图距10.8 c M。6种环境和育种值中,共检测到10个株高QTL和8个穗位高QTL,分布于第1、3、4、5、6、7、8和10染色体上,LOD介于3.25—8.36,加性效应值介于-6.41—8.70,单个QTL贡献率在6.96%—27.41%。这些QTL中有6个能在3种及以上环境中被检测到,且贡献率大于10.00%,是控制株高和穗位高的主效QTL。位于染色体Bin5.01/5.02区域同一位置的2个QTL在6种环境中被检测到,LOD介于3.25—6.48,加性效应值介于4.05—8.70。位于染色体Bin3.03/3.04区域同一位置的2个QTL在5种环境中被检测到,LOD介于4.71—8.36,加性效应值介于4.93—6.36。位于染色体Bin6.02区域同一位置的2个QTL在3种环境中被检测到,LOD介于3.52—5.21,加性效应值介于4.38—8.16。它们的增效等位基因均来自母本许178。条件QTL分析和非条件QTL分析的结果表明,这3个染色体区域的6个QTL是3个同时控制株高和穗位高的一因多效位点。【结论】玉米株高和穗位高的遗传受环境影响较大,大部分QTL只能在1种或2种环境中被检测到,3个主效QTL可以在3种及以上环境中被检测到,能够稳定地遗传,且贡献率高,有望在分子育种上得到应用。

Mapping QTL for Plant Height and Ear Height in Maize Under Multi-Environments

【Objective】QTL mapping for plant height and ear height were conducted with phenotype data collected from multi-environments, in order to identify stable QTL for plant height and ear height, which will provide a theoretical basis for molecular breeding of ideal plant type in maize.【Method】A total of 150 F7 recombinant inbred lines (RILs) population as the experimental materials were derived from the dominant maize inbred lines Xu178 and K12. Firstly, selecting 495 SSR markers from the MaizeGDB to detect polymorphism in parents, using markers with polymorphism to analyze population genotype. MapMaker V3.0 was used to part the linkage groups and to construct the linkage map. Secondly, QTL mapping for plant height and ear height were detected with inclusive composite interval mapping (ICIM) method of QTL IciMapping V4.0. Using phenotype data which were collected in two years and from three locations (Yulin, Shaanxi. Yangling, Shaanxi. Huludao, Liaoning. 2014-2015) and estimated the breeding value. Finally, conditional QTL analysis was conducted and compared with unconditional QTL analysis to discuss the genetic relationship between plant height and ear height at the QTL level.【Result】The genetic map was constructed with 191 filtered SSR markers, and the total length was 2 069.1 cM with the average length 10.8 cM. For plant height and ear height from 6 environments and estimated breeding value, ten plant height QTL and eight ear height QTL were detected, which distributed on the chromosomes 1, 3, 4, 5, 6, 7, 8 and 10, respectively, the LOD values ranged from 3.25 to 8.36, the additive effect from -6.41 to 8.70, and the range of individually explaining phenotypic variation was from 6.96% to 27.41%. Above of all QTL, six major QTL with LOD more than 10.00% could be detected in 3 or more environments. Of which, two QTL were detected on the same region of Bin5.01/5.02 in 6 environments, the LOD values ranged from 3.25 to 6.48, the additive effect from 4.05 to 8.70. Two QTL were detected on the same region of Bin3.03/3.04 in 5 environments, the LOD values ranged from 4.71 to 8.36, the additive effect ranged from 4.93 to 6.36. As well as two QTL were detected on the same interval of Bin6.02 in 3 environments, the LOD values ranged from 3.52 to 5.21, the additive effect ranged from 4.38 to 8.16, respectively. The favorite alleles of these QTL were all coming from female parent Xu178. Conditional analysis and unconditional analysis showed that the six QTL of three chromosomal regions were three pleiotropism loci which controlled plant height and ear height.【Conclusion】The inheritance of plant height and ear height of maize is strongly influenced by the environments, most of the QTL can be detected only in 1 or 2 environments. Three major QTL can be detected in 3 or more environments, and they are able to stable heredity with high phenotypic variation, it is expected that the major QTL could be applied in the molecular breeding.