以相对电导率研究菊花舌状花抗寒性遗传变异及其分子标记

Genetic variation and molecular markers for cold tolerance of ray florets by the relative electric conductivity analysis in chrysanthemum cultivars

以83个菊花(Chrysanthemum morifolium)品种舌状花为研究对象,测定其低温胁迫下的相对电导率,结合logistic方程评价2016~2017年两年度舌状花的低温半致死温度(LT50),并通过分子标记与LT50的关联分析挖掘与抗寒性相关的优异等位变异位点,筛选典型的抗寒材料。结果表明:两年菊花舌状花的LT50变化范围分别在-10.17~1.53和-10.30^-0.10°C,变异系数分别为34%和57%,这表明舌状花的抗寒性差异程度较大。基于混合线性模型(mixed linear model,MLM)方法的关联分析在2016和2017年度分别检测到10个和58个极显著相关位点,平均表型变异解释率为16.41%和16.76%;两年均检测到的变异位点有3个(E11M24-3、E11M24-4和E11M24-5),其中E11M24-3在两年均为增效位点,而E11M24-5均为减效位点;根据两年舌状花抗寒性和优异等位变异位点的有无,挖掘到Qx034、Qx138、Qx145、QD048这4个抗寒性强的品种。本研究初步明确了菊花舌状花抗寒性的遗传变异,获得了抗寒性相关分子标记和抗寒材料,拟为后续菊花抗寒性的遗传改良和分子标记辅助育种提供参考依据。

The study sets out to characterize the extent of genetic variation for cold tolerance in a collection of83 chrysanthemum(Chrysanthemum morifolium)cultivars by testing their ray florets in terms of semi-lethal temperature(LT50),which was determined by the relative electric conductivity and logistic equation in two years of 2016 and 2017,and to identify molecular markers for cold tolerance by association analysis and materials with high cold tolerance.The results show that LT50 varied in a range of-10.17–-1.53 and-10.30–-0.10°C in 2016and 2017,respectively;the coeffecient of variation averaged at 34%and 57%across the two years,indicating high level of genetic variation for cold tolerance of ray florets.Association mapping based on mixed linear model(MLM)method identified 10 and 58 markers for cold tolerance at P<0.01 in 2016 and 2017,and the average proportion of the explained phenotypic variance was calculated at 16.41%and 16.76%,respectively.Three of the associated markers(E11M24-3,E11M24-4 and E11M24-5)were predictive in each of two years.E11M24-3 showed a positive effect for cold tolerance whereas E11M24-5 showed a negative effect across the two years.On the basis of the favorable allele and the result of LT50-based cluster analysis in two years,four cold-tolerance varieties,Qx034,Qx138,Qx145 and QD048,were identified as potential donors for future improvement of cold tolerance in chrysanthemum.The findings of our study help to make clear the genetic variation for cold tolerance in ray florets of chrysanthemum,and the identified markers and tolerant materials would provide a reference for marker-assisted selection and genetic improvement of cold tolerance in the future.