谷子株高及穗部性状主基因+多基因混合遗传模型分析

【目的】株高和穗部性状是影响谷子产量的关键性状。探究谷子株高及穗部性状表型变异的遗传规律,为相关性状的遗传改良与基因定位提供参考依据。【方法】以谷子优质品种豫谷18为共同父本,分别与黄软谷和红酒谷杂交,构建2个分别包含250个家系的重组自交系F₇群体（YYRIL和YRRIL）。采用主基因+多基因混合遗传模型,对YYRIL和YRRIL群体在2个环境下的株高、穗长、穗下节间长、穗码数、穗粒重等5个农艺性状的表型数据进行遗传分析。【结果】5个性状在所有环境中均表现连续变异且存在超亲分离现象,峰度和偏度绝对值小于1,近似正态分布,呈现数量性状的典型遗传特点。性状间相关性分析表明株高与穗长、穗下节间长在所有环境中均呈极显著正相关,穗码数与穗粒重呈极显著正相关。遗传模型分析显示YYRIL和YRRIL群体株高的最适遗传模型分别为PG-AI和PG-A多基因模型,多基因遗传率分别为95.15%和91.27%。2个群体穗码数的最适模型均为PG-AI,多基因遗传率为70.07%—71.58%。穗下节间长在2个群体的最适遗传模型分别为4MG-CEA和3MG-CEA,均为等加性主基因模型。穗下节间长在YYRIL群体的主基因遗传率为9.69%,4对主基因加性效应值相等,均为-0.34,具有负向效应;穗下节间长在YRRIL群体的主基因遗传率为45.78%,3对主基因加性效应值相等,均为1.17,具有正向效应。穗长在YYRIL群体的最适模型为MX2-ED-A,即2对显性上位主基因+加性多基因模型,主基因遗传率为43.56%,多基因遗传率为50.56%。控制穗长的2对主基因加性效应值分别为-1.21、1.68,多基因加性效应较小,为-0.0017;穗长在YRRIL群体的最适模型为MX2-AE-A,即2对累加作用主基因,加性多基因混合遗传模型;穗长的主基因遗传率为46.40%,多基因遗传率为46.91%。控制穗长的第1对主基因加性效应值为1.53,具有正向效应,第1对主基因加性×第2对主基因加性上位性互作效应值是0.60,多基因加性效应值为-0.47,表现为较低的负向遗传效应。穗粒重在YYRIL群体的最适遗传模型为MX2-ED-A;符合2对显性上位主基因+加性多基因模型,主基因遗传率为69.09%,多基因遗传率为12.08%;控制穗粒重的2对主基因加性效应值分别为0.58、5.82,以第2对主基因的加性效应为主,多基因加性效应值为-3.81。穗粒重在YRRIL群体的最适遗传模型为3MG-PEA,即3对部分等加性主基因遗传模型;穗粒重的主基因遗传率为81.10%,3对主基因加性效应值分别为-2.68、-2.68和2.66,前2对主基因的加性效应值相同,且均为负向效应。【结论】谷子株高、穗码数的最适遗传模型相似,均服从多基因遗传,遗传率较高,受环境影响较小;穗下节间长的遗传受主基因控制,主基因遗传率偏低,受环境影响较大,在栽培中应充分考虑环境因素;穗长遗传受主基因和多基因共同控制;穗粒重在2个群体均服从主基因遗传,主基因遗传率较高,可能存在主效QTL。

Analyzing Genetic Effects for Plant Height and Panicle Traits by Means of the Mixed Inheritance Model of Major Gene Plus Polygene in Foxtail Millet

【Objective】Plant height and panicle traits are key yield-dependent traits in foxtail millet. The objective was to probe into inheritance patterns of plant height and panicle traits and provide a reference basis for genetically improving related traits and mapping their genes. 【Method】Yugu 18, a high performing foxtail millet variety, was arranged as the male parent to cross two foxtail millet varieties, Huangruangu and Hongjiugu, and thus two F₇ populations of which each was composed of recombinant inbred lines involving 250 family lines（YYRIL and YRRIL）were established. Phenotypic data of Five agronomic traits of the two populations, plant height, panicle length, internode length under panicle, spikelet number per panicle and grain weight per panicle, were genetically examined in two different environments using the mixed inheritance model of major gene plus polygene. 【Result】In these two environments, all the five agronomic traits showed continuous variations with their kurtosis and skewness values standing at the absolute value of less than 1 and thus presenting a distribution close to a normal distribution, were characterized by typical inheritance of quantitative traits; some of these traits saw super-parent separation phenomena. The correlation analysis among the traits showed that the plant height appeared significantly and positively correlated with the panicle length, and an extremely significantly positive correlation between spikelet number per panicle and grain weight per panicle was also found in the two environments. The analysis by the inheritance model showed that the best inheritance models for the plant height of the YYRIL and YRRIL population were the PG-AI and PG-A polygene models, and the heritability of the polygenes standing at 95.15% and 91.27%, respectively. The best inheritance models for the spikelet number per panicle of the two populations were the PG-AI, with the heritability of the polygenes standing at 70.07%-71.58%. The best inheritance models for the internode length under panicle of the two populations were the 4MG-CEA and 3MG-CEA of which both were models for equally additive major genes. In YYRIL, the heritability of the major genes for the internode length under panicle stood at 9.69%, and the four pairs of major genes had an equal additive effect value of -0.34, taking negative effect; and in the YYRIL, the heritability of the major genes for the internode length under panicle stood at 45.78%, and the 3 major gene pairs in question had an equal additive effect value of 1.17, taking positive effect. In the YYRIL, the best inheritance model for the panicle length was the MX2-ED-A, a model for two pairs of dominant epistatic major genes and additive polygenes, with the heritability of the major genes and polygenes standing at 43.56% and 50.56%, respectively. the two pairs of panicle length-dependent major genes separately had the additive effect values of -1.21 and 1.68 and the polygenes had a lower additive effect value of -0.0017; in the YRRIL, the best inheritance model for the panicle length was the MX2-AE-A, a mixed inheritance model for two pairs of accumulative effect major genes and additive polygenes; the major genes and polygenes for the panicle length had heritability values standing at 46.40% and 46.91%, respectively. The first pair of panicle length-dependent major genes had an additive effect value of 1.53, taking positive effect; The additive and epistatic interactions effect value of the first×the second pairs of major genes were 0.60. The polygenes had an additive effect value of -0.47, taking the lower negative inheritance effect. In the YYRIL, the best inheritance model for the grain weight per panicle was the MX2-ED-A; the grain weight per panicle followed the inheritance model for two pairs of dominant epistatic major genes + additive polygenes with the heritability of the major genes and polygenes standing at 69.09% and 12.08%; the additive effect values of the two pairs of grain-weight per panicle-dependent major genes were separately 0.58 and 5.82, with the additive effect of the second pair of major genes dominating, and the additive effect value of polygenes stood at a value of -3.81. In the YRRIL, the best inheritance model for the grain weight per panicle was the 3MG-PEA, an inheritance model for three pairs of partially equal additive major genes; the heritability of the grain weight per panicle-dependent major genes stood at 81.10% and the additive effect values of the three pairs of major genes separately were -2.68, -2.68and 2.66, all taking negative effect. 【Conclusion】In foxtail millet, the plant height and spikelet number per panicle had similar inheritance models, were all under polygenic control with a higher heritability and environmentally affected to a slight content; the inheritance of the internode length under panicle was genetically controlled by major genes, which had a lower heritability and were environmentally affected to a great extent, and thus environmental factors should be taken into full account in production; the panicle length was genetically controlled jointly by major genes and polygenes; the grain weight per panicle was genetically controlled by major genes with a high heritability in both of the two population and probably carried major QTL.