Genetic diversity analysis of agronomic traits and elite accession selection in 263 cucumber germplasm resources

Abstract

[Objective] To analyze the genetic diversity of 236 cucumber germplasm resources and select elite accessions and to provide suitable parent materials for new varieties and reference for exploiting elite genes and utilizing, protecting the germplasm resource.

[Method] A total of 236 cucumber germplasm resources from Yunnan, other provinces of China and other countries were used in this experiment, 12 traits including 2 qualitative traits and 10 quantitative traits were analyzed. The genetic diversity and comprehensive evaluation were carried out by using genetic variation analysis, correlation analysis, principal component analysis and cluster analysis, and elite germplasm resources were selected.

[Result] The variation coefficient of female flower node rate was the maximum (145.46%) and leaf shape index variation coefficient was the minimum (4.68%), the variation coefficient of quantitative traits was higher than that of qualitative traits. The average genetic diversity index was 1.633, the genetic diversity index of cotyledon width was the highest (2.092) and leaf color genetic diversity index was the lowest (0.389). Correlation analysis showed the female flower node rate was significantly positively correlated to leaf color ( P<0.05, the same below), while it was extremely significantly positively correlated with cotyledon length, cotyledon width, fruiting habits, leaf length and leaf shape index ( P<0.01, the same below), it was extremely significantly negatively correlated with the first female flower node, male flower node rate, internode length and main stem length. The first female flower node was extremely significantly positively correlated with male flower node rate and fruiting habits, but it was significantly negatively correlated with leaf color index, and extremely significantly negatively correlated with female flower node rate and cotyledon width. Principal component analysis of agronomic traits showed that cumulative contribution rate of the first five principal components was 80.823%, including the first principal component female flower node rate, the second principal component leaf length, the third principal component the first female flower node, the fourth principal component cotyledon length and the fifth principal component leaf color. The 236 cucumber accessions were classified into eight groups. Group VI and VII could be used as male parent in hybrid breeding since they had strong growth vigor and high male flower rate. Group VIII could be used as female parent since they had high female flower rate and high seed setting rate.

[Conclusion] The 236 cucumber germplasm resources have high genetic diversity, genetic variation of major agronomic traits is abundant. In cucumber breeding, cucumber yield can be increased through selection of leaf size, leaf color, the first female flower node, fruiting habit, female flower node rate. Early maturity and high yield of cucumber depend not only on the appearance of the first female flower node, but also the male flower rate and the fruiting habits.

Abstract

摘要 【目的】 分析国内外236份黄瓜种质资源的遗传多样性, 筛选优质种质, 为黄瓜新品种选育提供优良亲本材 料, 也为优良基因挖掘及种质资源利用、保护提供参考。 【方法】 以来自云南省内、省外及国外的236份黄瓜种质为试 料, 对其12个性状 (2个质量性状和10个数量性状) 进行测定, 通过遗传变异分析、相关性分析、主成分分析和聚类分析 对这些种质进行遗传多样性分析及综合评价, 筛选出优质种质。 【结果】 236份黄瓜种质变异系数最大的是雌花节率, 为145.46%, 变异系数最小为叶形指数, 为4.68%, 数量性状变异系数高于质量性状; 平均遗传多样性指数为1.633, 以 子叶宽最高, 为2.092,以叶色最低, 为0.389。雌花节率与叶色呈显著正相关 ( P<0.05, 下同), 与子叶长、子叶宽、结瓜 习性、成株叶长和叶形指数呈极显著正相关( P<0.01, 下同), 与第一雌花出现节位、雄花节率、节间长和主蔓长呈极显 著负相关; 第一雌花出现节位与雄花节率和结瓜习性呈极显著正相关, 与叶形指数呈显著负相关, 与雌花节率和子叶 宽呈极显著负相关。主成分分析结果显示, 前5个主成分因子累计贡献率达80.823%,第一因子是雌花节率主分量, 第二因子是成株叶宽主分量, 第三因子是第一雌花出现节位主分量, 第四因子是子叶长主分量, 第五因子是叶色主分 量。236份黄瓜种质材料分成八大类群 (I ~VIII), 其中第VI类群和VII类群的生长势强, 雄花占比多, 在育种中可作为 父本材料, 第观类群的雌花占比多, 单性结实率高, 在育种中可作为母本材料。 【结论】 236份黄瓜种质具有丰富的遗传 多样性, 选择育种潜力巨大。在黄瓜育种时, 可将叶面积、叶色、第一雌花出现节位、结瓜习性和雌花节率等性状作为 产量性状进行改良, 且选育早熟高产品种时应注重第一雌花出现节位、雄花节率和结瓜习性等性状。