异色菊×菊花脑种间杂交后代耐寒性的遗传变异

Genetic Variation for Cold Tolerance in an Interspecific C. dichrum × C. nankingense Population

为明确菊花野生近缘种耐寒性的遗传变异机制,本研究以二倍体近缘种异色菊(不耐寒)×菊花脑(耐寒)种间F_1为材料,研究脚芽期的低温半致死温度(LT_(50))、脚芽数量和脚芽高度3个耐寒性状的杂种优势、主基因效应和相关性,并利用隶属函数法鉴定出高耐寒株系。结果表明,种间F_1群体的LT_(50)、脚芽数量和脚芽高度变异较大,变异系数分别为21.75%、51.80%和41.95%;3个耐寒性状均存在一定程度的杂种优势,其中脚芽高度的中亲优势达到极显著差异(P<0.01)。混合遗传模型分析表明,LT_(50)、脚芽数量和脚芽高度分别由2对加性-显性-上位性主基因控制、1对加性-显性主基因控制和1对加性主基因控制。相关性分析表明,LT_(50)与脚芽数量、脚芽高度存在极显著负相关(P<0.01),为LT_(50)的间接选择提供了依据。基于耐寒性状隶属函数值的聚类分析将供试材料分为高耐寒、耐寒、低耐寒和不耐寒4个等级,其中高耐寒株系将为今后菊花耐寒性的遗传改良提供重要的亲本材料。本研究明确了菊花二倍体近缘种异色菊×菊花脑种间杂交后代的遗传变异机制,为今后耐寒性QTL定位和菊花耐寒育种提供了一定的参考依据。

To understand the genetic variation of cold tolerance in chrysanthemum related species and provide some reference to genetic improvement for cold tolerance of chrysanthemum, we investigated the heterosis, major gene effect and correlation of the 3 cold tolerance related traits, i.e., semi-lethal temperature（LT50）, the rhizome number and height in an interspecific F_1 hybrid population derived from diploid species C. dichrum and C. nankingense, and screened some high cold tolerant lines for future breeding use. The result indicated that LT50, rhizome number and rhizome height varied widely in the interspecific F1 population, with variation coefficient of 21.75%, 51.80% and 41.95%, respectively. Mid-parent heterosis with different level was observed for the 3 cold tolerance traits, with significant（P〈0.01） for rhizome number and rhizome height. Mixed inheritance model analysis revealed that LT50was mainly controlled by two pairs of major genes with additivity-dominance-epistasis effect, rhizome quantity was controlled by one pair of major genes with additivity-dominance effect, and rhizome height was controlled by one pair of major genes with additive effect. Correlation analysis showed that LT50 was negatively correlated with rhizome quantity and rhizome height at 0.01 level, providing some evidences for indirect selection of LT50. In addition, the membership function-based cluster analysis divided the investigated materials into four types, i.e., high cold tolerance, cold tolerance, low cold tolerance and cold sensitivity, of which the high cold tolerant lines could be used as potential parents in chrysanthemum breeding program targeting cold tolerance. The findings of the current study clarified the genetic variations of cold tolerance in diploid C. dichrum and C. nankingense, and will laid an important foundation for future QTL analysis and breeding for cold tolerance in chrysanthemum.