Guzmán Luis F, Machida-Hirano Ryoko, Borrayo Ernesto, Cortés-Cruz Moisés, Espíndola-Barquera María Del Carmen, Heredia García Elena
Centro Nacional de Recursos Genéticos, Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias Tepatitlán de Morelos, Mexico.
Gene Research Center, University of Tsukuba Tsukuba, Japan.
Front Plant Sci. 2017 Feb 24;8:243. doi: 10.3389/fpls.2017.00243. eCollection 2017.
Mexico, as the center of origin of avocado ( Mill.), harbors a wide genetic diversity of this species, whose identification may provide the grounds to not only understand its unique population structure and domestication history, but also inform the efforts aimed at its conservation. Although molecular characterization of cultivated avocado germplasm has been studied by several research groups, this had not been the case in Mexico. In order to elucidate the genetic structure of avocado in Mexico and the sustainable use of its genetic resources, 318 avocado accessions conserved in the germplasm collection in the National Avocado Genebank were analyzed using 28 markers [9 expressed sequence tag-Simple Sequence Repeats (SSRs) and 19 genomic SSRs]. Deviation from Hardy Weinberg Equilibrium and high inter-locus linkage disequilibrium were observed especially in , and . Total averages of the observed and expected heterozygosity were 0.59 and 0.75, respectively. Although clear genetic differentiation was not observed among 3 botanical races: , and , the analyzed Mexican population can be classified into two groups that correspond to two different ecological regions. We developed a core-collection by K-means clustering method. The selected 36 individuals as core-collection successfully represented more than 80% of total alleles and showed heterozygosity values equal to or higher than those of the original collection, despite its constituting slightly more than 10% of the latter. Accessions selected as members of the core collection have now become candidates to be introduced in cryopreservation implying a minimum loss of genetic diversity and a back-up for existing field collections of such important genetic resources.
墨西哥作为鳄梨（Persea americana Mill.）的起源中心，拥有该物种丰富的遗传多样性。对其进行鉴定不仅可以为了解其独特的种群结构和驯化历史提供依据，还能为其保护工作提供信息。尽管多个研究小组对栽培鳄梨种质进行了分子特征研究，但在墨西哥尚未开展此类研究。为了阐明墨西哥鳄梨的遗传结构及其遗传资源的可持续利用，利用28个标记（9个表达序列标签 - 简单序列重复（SSR）和19个基因组SSR）对保存在国家鳄梨基因库种质收集中的318份鳄梨种质进行了分析。尤其在[此处原文缺失具体信息]中观察到偏离哈迪 - 温伯格平衡和高度的位点间连锁不平衡。观察到的杂合度和预期杂合度的总平均值分别为0.59和0.75。尽管在三个植物变种[此处原文缺失具体变种名称]之间未观察到明显的遗传分化，但分析的墨西哥种群可分为两组，分别对应两个不同的生态区域。我们通过K - 均值聚类方法开发了一个核心种质库。选定的36个个体作为核心种质成功代表了超过80%的总等位基因，并且尽管其仅占原始收集种质的略多于10%，但其杂合度值等于或高于原始收集种质。被选为核心种质库成员的种质现在已成为进行冷冻保存的候选对象，这意味着遗传多样性损失最小，并为这种重要遗传资源的现有田间收集提供备份。
