Genetic diversity in accessions of melon belonging to momordica group

ABSTRACT The genetic divergence of melon genotypes belonging to momordica group, collected in five Brazilian States, was estimated, and the relative contribution of the morphological characters was determined for the genetic variability. The experimental design was randomized blocks, with four replicates. We evaluated 19 accessions of melon, momordica group, two accessions of cantaloupensis group and two commercial cultivars of inodorus group. These genotypes were characterized by 42 morphological descriptors. The data were submitted to Tocher and UPGMA grouping methods using the genetic dissimilarity matrix, using Mahalanobis’ distance. Singh criterion was used to identify the relative contribution of each character to the genetic divergence. Four groups of similarity were obtained in both multivariate techniques, with agreement between hierarchical UPGMA and Tocher grouping methods. The characters: pistil scar size, soluble solid content, seed length, fruit length and cotyledon length contributed with approximately 53.86% to genetic divergence among genotypes.【摘要】本研究对巴西5个州收集的苦瓜组（momordica group）甜瓜基因型的遗传分化水平进行了估算，并明确了各形态性状对遗传变异的相对贡献。试验采用随机区组设计，设置4次生物学重复。本研究共评估了19份苦瓜组甜瓜种质、2份厚皮甜瓜组（cantaloupensis group）种质以及2份冬甜瓜组（inodorus group）商业栽培品种。采用42个形态学性状对供试基因型进行了系统表征。试验数据基于马氏距离（Mahalanobis’ distance）构建遗传差异矩阵，并分别采用托彻聚类法（Tocher）与非加权组平均法（UPGMA）进行聚类分析。采用辛格准则（Singh criterion）分析各性状对基因型遗传分化的相对贡献。两种多元统计分析方法均得到了4个相似性类群，且层级式非加权组平均法与托彻聚类法的聚类结果一致性较好。其中，雌蕊痕大小、可溶性固形物含量、种子长度、果实长度及子叶长度这5个性状，对供试基因型间遗传分化的总贡献率约为53.86%。