烤烟几种主要化学成分的遗传分析

Genetic Analysis for Chemical Constituents in Flue-cured Tobacco (Nicotiana tabacum L.)

以14个烤烟品种(系)及其配制的41个杂交组合为材料,利用包括基因型与环境互作的加性显性遗传模型进行烟叶化学成分的遗传和相关分析。结果表明,烟碱主要受加性主效应控制,总糖、还原糖、两糖差、总氮、蛋白质、氧化钾受显性×环境互作效应影响最大。没有一个参试亲本和杂交组合同时在两糖差、烟碱上表现负向效应,而在氧化钾上表现正向效应。性状相关分析表明,总氮、烟碱、蛋白质这类含氮化合物之间呈正向表现型相关、基因型相关和加性遗传相关,而与总糖、还原糖呈负向表现型相关、基因型相关和加性遗传相关。两糖差、烟碱、含钾量之间各相关系数较小或无显著相关,可以通过广泛配制组合或扩大后代群体同步减少两糖差,降低烟碱,提高含钾量。

Chemical constituents are the major factors attributed to leaf quality in the flue-cured tobacco, and are sensitive to environments. Despite inheritance of some chemical characteristics was reported, information on genotype × environment interaction is generally lacking. The objectives of this research were to evaluate the genetic effects for chemical constituents, and to understand the genetic correlations among the traits analyzed. By using randomized complete block design, 14 flue-cured tobacco cultivars （or breeding lines） and their 41 Fi crosses were grown in four locations with two replications at each location in Yunnan Province in 2002. Percents of total sugar, reducing sugar, sugar difference between percents of total sugar and reducing sugar, percents of total nitrogen, nicotine, protein and K20 were evaluated for the cured leaves. A genetic model including additive and dominance effects and their interaction with environments was applied for genetic and correlation analyses. Additive, dominance, additive by environment interaction and dominance by environment interaction genetic effects appeared to play an importance role in the inheritance of the chemical constituents measured. Percent nicotine was mainly controlled by the additive main effects. The ratio of additive variance to phenotypic variance was 0.302 （See in Table 1）. Dominance x environment interaction effects played a major role for total sugar, reducing sugar, sugar difference, total nitrogen, protein, and K20. No parents and crosses investigated had negative effects for sugar difference and nicotine, but positive effects for K20. The analysis of correlation among chemical constituents revealed that there were positive correlations of phenotypic, genotypic and additive effects among the nitrogenous compounds such as total nitrogen, nicotine, protein, and negative correlation with total sugar and reducing sugar for phenotypic, genotypic and additive effects. Sugar difference, nicotine and K20 had low or no correlation with each others （Table 4） . The predominance of additive genetic variance for nicotine in this study suggests that the most effective breeding procedures for improving nititine content will be those which lead to the superior homozygous lines. The predominance of dominance by environment interaction variance for sugar difference and K20 percent suggests that the utility of heterosis should be considered in specific environments. It is possible to decrease sugar difference and nicotine, and increase K20 simultaneously in tobacco leaves by making more crosses or enlarging offspring population.