Department of Plant Breeding, Swedish University of Agricultural Sciences, P.O. Box 101, 23053 Alnarp, Sweden.
Department of Botany, University of Dar es Salaam, P.O. Box 35060, Dar es Salaam, Tanzania.
Genes (Basel). 2021 Jan 4;12(1):63. doi: 10.3390/genes12010063.
Tanzania has been growing avocado for decades. A wide variability of the avocado germplasm has been found, and the crop is largely contributing to the earnings of the farmers, traders, and the government, but its genetic diversity is scantly investigated. With the purpose of comparing morphological and genetic characteristics of this germplasm and uncovering the correlation between them and the geographical location, 226 adult seedling avocado trees were sampled in southwestern Tanzania. Their morphological characters were recorded, and their genetic diversity was evaluated based on 10 microsatellite loci. Discriminant analysis of principal components showed that the germplasm studied consisted of four genetic clusters that had an overall average gene diversity of 0.59 and 15.9% molecular variation among them. Most of the phenotypes were common in at least two clusters. The genetic clusters were also portrayed by multivariate analysis and hierarchical clustering for the molecular data but not for the morphology data. Using the Mantel test, a weak significant correlation was found between the genetic, morphological, and geographical distances, which indicates that the genetic variation present in the material is weakly reflected by the observed phenotypic variation and that both measures of variation varied slightly with the geographical sampling locations.
坦桑尼亚种植鳄梨树已有数十年的历史。研究人员发现，鳄梨种质资源具有广泛的变异性，该作物在很大程度上为农民、贸易商和政府带来了收入，但对其遗传多样性的研究却很少。为了比较该种质资源的形态和遗传特征，并揭示它们与地理位置之间的相关性，研究人员在坦桑尼亚西南部采集了 226 株成年鳄梨树幼苗样本。记录了它们的形态特征，并基于 10 个微卫星标记评估了它们的遗传多样性。主成分判别分析表明，所研究的种质资源由四个遗传群组成，它们的总体平均基因多样性为 0.59，群体间有 15.9%的分子变异。大多数表型至少在两个群体中是共同的。遗传群也通过多变量分析和分子数据的层次聚类来描绘，但不是通过形态数据。通过 Mantel 检验发现，遗传、形态和地理距离之间存在微弱的显著相关性，这表明材料中存在的遗传变异在一定程度上反映了观察到的表型变异，而且这两种变异都随着地理采样地点的变化而略有变化。
