美洲黑杨表型核心种质库构建

目的 分析美洲黑杨不同类群的表型和生理特点，对比不同取样策略构建的表型核心种质库的有效性和代表性，科学有效地保存和管理种质资源的表型多样性，为美洲黑杨种质资源的深入挖掘和利用提供科学依据，同时为其他物种表型核心种质库的构建提供参考。 方法 基于前期表型生理性状群体结构的分析结果对美洲黑杨种质资源进行分组，通过多重比较分析不同类群的21个表型和生理性状的特点。计算无性系间的欧氏距离，利用组间联接法对每个类群的个体进行聚类，分别采用随机取样、偏离度取样、位点优先取样和性状频率取样策略对无性系进行筛选，构建表型核心种质库，对比分析选择最佳的取样策略。在表型核心种质库的基础上通过添加种质使表型保留比例（RPR）达到100.00%构建表型优化核心种质库，通过比较核心种质库与原始种质库的均值、方差、极差、变异系数和RPR对其代表性和有效性进行评价。 结果 美洲黑杨Was种源个体的高生长量、叶片数和叶片养分含量较高；Iow和Que种源无性系的根系生长发达；Mis、Lou和Ten种源无性系的茎生长量、叶片形态和单叶生长量突出。通过性状频率取样策略构建的表型核心种质库用最少的种质代表了原始种质库的多样性信息，核心种质库的有效性优于随机取样、偏离度取样和位点优先取样策略构建的种质库，最终构建了包括27个种质的表型核心种质库，取样比例为10.47%，均值差异百分率（MD）、方差差异百分率（VD），极差符合率（CR）、变异系数变化率（VR）和RPR分别为0.00%、80.95%、100.00%、148.94%和90.85%。在核心种质库的基础上添加5个补充种质构建表型优化核心种质库，使RPR达到100.00%，其MD、VD、CR和VR分别为0.00%、71.43%、100.00%和142.19%。通过PCoA分析表明：表型核心种质库和优化核心种质库均具有良好的代表性。 结论 不同类群的美洲黑杨种质资源的根、茎、叶生长性状存在明显差异。通过性状频率取样策略构建的美洲黑杨表型核心种质库和优化核心种质库可以在保留原始种质多样性的基础上，较大限度的降低种质库的规模和冗余度，提高种质库表型变异水平，为有效保存、管理和利用美洲黑杨种质资源提供科学依据。

Construction of Phenotypic Core Collection of Populus deltoides

Objective To analyze the phenotypic and physiological characteristics of different groups of P. deltoides, and to compare the effectiveness and representativeness of the phenotypic core collection constructed by different sampling strategies. Method Based on the results of population structure analysis of phenotypic and physiological traits analyzed in previous studies, the P. deltoides resources were grouped, and 21 phenotypic and physiological characters of different groups were analyzed by multiple comparison. The Euclidean distance between clones was calculated, and the individuals of each group were clustered by the method of intergroup connection. The clones were screened by random sampling, deviation degree sampling, locus priority sampling and trait frequency sampling strategies, respectively. The best sampling strategy was selected by comparing and analyzing the diversity of core collection constructed by different sampling strategies. On the basis of the phenotypic core collection, the optimized core collection was constructed by making the phenotypic retention ratio (RPR) reaching 100.00%. The representativeness and validity of core collections were evaluated by comparing the mean, variance, range, coefficient of variation and RPR between the core and the original collections. Result The height growth, leaf number and leaf nutrient characters of the individuals of the provenance ‘Was’ were higher. The roots of the clones of provenances ‘Iow’ and ‘Que’ were developed. The stem growth, leaf morphology and single leaf growth of the clones of provenances ‘Mis’, ‘Lou’ and ‘Ten’ were prominent. The phenotypic core collection constructed by the strategy of character frequency sampling represented the diversity information of the original collection with the least collection. The effectiveness of the core collection was better than that constructed by the strategy of random sampling, deviation degree sampling and site priority sampling. Finally, the phenotypic core collection consisting of 27 clones was constructed, with the sampling ratio of 10.47%. The mean difference percentage (MD), variance difference percentage (VD), range coincidence rate (CR), coefficient of variation coincidence rate (VR) and RPR were 0.00%, 80.95%, 100.00%, 148.94% and 90.85%, respectively. On the basis of core collection, 5 individuals were added to construct phenotype optimized core collection, so that the RPR reached 100.00%, and MD, VD, CR and VR were 0.00%, 71.43%, 100.00% and 142.19%, respectively. The results of PCoA analysis showed that the phenotypic core collection and the optimized core collection were well representative. Conclusion There are significant differences in root, stem and leaf growth traits among different groups of P. deltoides germplasm resources. Through the strategy of character frequency sampling, the core collection of phenotype and the optimization of core collection of P. deltoides could retain the diversity of the original collection, greatly reduce the size and redundancy of the collection, and improve the variation level. The results could provide scientific basis for the conservation, management and utilization of P. deltoides germplasm resources.