切花菊苗期抗寒性评价及相关的分子标记挖掘

为明确切花菊抗寒性的遗传变异,挖掘优异基因资源,本研究利用电导率结合Logistic方程评价83个切花菊品种苗期叶片的低温半致死温度(LT₅₀),通过关联分析探究抗寒性相关的优异等位变异位点并筛选抗性品种资源。结果表明,83个切花菊品种的LT₅₀在-10.99～1.86℃之间,变异系数为79.81%,说明切花菊抗寒性差异较大;依据LT₅₀的聚类分析将83份供试品种分为抗寒、中抗寒、低抗寒和不抗寒4种类型,分别占21.67%、22.89%、32.53%和22.89%。基于混合线性模型进行关联分析,共检测到11个等位变异位点(P<0.01),表型效应值为-3.51～0.83,表型变异贡献率为11.54%～18.83%;其中8个变异位点表现为增效,特别是携带E7M12-13位点品种的耐寒性显著(P<0.01)高于未携带该位点的品种。此外,根据增效位点挖掘到南农金柠檬、Qx097、QD028、Qx049、Qx153和Qx008等6个抗寒性强的品种资源。本研究结果为今后菊花耐寒性的遗传改良和分子标记辅助育种奠定了重要基础。

Genetic Variation and Molecular Markers for Cold Tolerance of Cut-chrysanthemum Cultivars at Seedling Stage

To make clear the genetic variation for cold tolerance and to dig associated elite alleles in cut chrysanthemum, the present study was set out to assess the cold tolerance in terms of semi-lethal temperature (LT₅₀) in a panel of 83 cultivars at seedling stage using the relative electric conductivity and logistic equation. The favorable alleles responsible for cold tolerance were analyzed via association analysis. The results showed that LT₅₀ varied between-10.99~1.86℃ with a variation coefficient of 79.81%, which indicated a high level of genetic variation for the cold tolerance in the investigated cut chrysanthemums. LT₅₀-based cluster analysis grouped the 83 cut chrysanthemums into 4 types, including tolerant (21.67%), moderate tolerant (22.89%), low tolerant (32.53%) and cold-sensitive cultivars (22.89%). The mix linear model-based association analysis identified 11 SSR markers that were significantly associated with LT₅₀ (P<0.01), with phenotypic effect in a range of -3.51~0.83 and individually explained phenotypic variation varying in 11.54%~18.83%. In the 11 significant alleles, 8 favorable alleles were helpful to enhance cold tolerance, particularly the E7M12-13 showed a significant level of phenotypic effect on LT₅₀ at P<0.01, and 6 cold-tolerant cultivars, i.e., Nannong Jinningmeng, Qx097, QD028, Qx049, Qx153, and Qx008 that carry the favorable allele were finally screened out for future use. The findings of the present study add new understanding to the genetic variation of cold tolerance in cut chrysanthemum and will provide guidelines for genetic improvement and molecular marker assisted selection breeding for the target trait in future.