Selection in segregating populations of ornamental pepper plants (Capsicum annuum L.) using multidimensional scaling

ABSTRACT Multidimensional scaling is a multivariate analysis technique that can be used to exploit genetic diversity, aiming at the selection of Capsicum genotypes with desirable characteristics for in-pot ornamental purposes. This work aimed to select genotypes with ornamental potential within F4 populations of ornamental pepper plants. Three F4 families were used (17.18, 30.16, and 56.8). The genotype distance matrices were estimated based on qualitative and quantitative descriptors, separately, combining the standardized distances of Gower and Mahalanobis, respectively. The relation of the distance between genotypes was graphically studied through non-metric multidimensional scaling. Kruskal' Stress was used as the measured misadjustment of the nMDS solution. There is genetic diversity within the analyzed families, allowing to practice selection. The selection in family 17.18 of genotypes 6 and 32 is recommended, as well as in family 30.16 of genotypes 22 and 4, and family 56.8 of genotypes 15 and 36, since they present important characteristics for ornamental purposes. The selection of genotypes is more efficient when using mixed data since it provides a more complete genetic diversity in an improvement program.

摘要：多维尺度分析（Multidimensional Scaling）是一类多元分析技术，可用于挖掘遗传多样性，旨在筛选出适配盆栽观赏需求的优良辣椒属（Capsicum）基因型。本研究以观赏辣椒F₄代群体为材料，筛选具有观赏潜力的基因型。试验共采用3个F₄家系（17.18、30.16及56.8）。分别基于定性与定量描述符构建基因型距离矩阵，分别结合标准化的高氏（Gower）距离与马氏（Mahalanobis）距离进行计算。通过非度量多维尺度分析（non-metric Multidimensional Scaling, nMDS）对基因型间的距离关系开展图形化分析，并以克鲁斯卡尔应力（Kruskal' Stress）作为衡量非度量多维尺度分析拟合偏差的指标。结果表明，各供试家系内均存在遗传多样性，可开展基因型筛选工作。本研究推荐筛选17.18家系中的6号、32号基因型，30.16家系中的22号、4号基因型，以及56.8家系中的15号、36号基因型，上述材料均具备观赏用途所需的关键性状。此外，结合定性与定量混合数据开展基因型筛选效率更高，能够为遗传改良项目提供更全面的遗传多样性挖掘途径。