Molecular diversity in a germplasm collection of avocado accessions from the tropical and subtropical regions of China

Abstract Avocado is an economically important crop and widely cultivated in the tropical and subtropical regions of China, whereas little is known about its genetic diversification. Twenty-six EST-SSR markers were developed based on avocado EST sequences. Molecular characterization was applied to assess the genetic relationships among different accessions. In total, nine gSSRs and nine EST-SSRs were selected to illuminate the genetic relationships within the 92 samples. Diversity parameters associated to the selected markers indicated the relatively low genetic diversity and a certain degree of inbreeding in the 92 avocado accessions. Clustering method and principal coordinate analysis clearly distinguished the accessions in accordance to the botanical races and geographic regions by molecular characterization. Moreover, the botanical race or hybrids of some unknown race accessions from different geographic origins could be determined based on known genotypes in the same cluster..

摘要：牛油果是具有重要经济价值的作物，在中国热带及亚热带区域广泛种植，但目前对其遗传分化的认知仍较为匮乏。本研究基于牛油果的表达序列标签（Expressed Sequence Tag, EST）序列开发了26个表达序列标签-简单序列重复（Expressed Sequence Tag-Simple Sequence Repeat, EST-SSR）标记；通过分子表征技术分析不同种质资源间的遗传关系。最终选取9个基因组简单序列重复（Genomic Simple Sequence Repeat, gSSR）标记与9个EST-SSR标记，对92份样本的遗传关系进行解析。所选标记的多样性参数分析结果显示，该92份牛油果种质资源的遗传多样性水平相对较低，且存在一定程度的近交现象。聚类分析与主坐标分析可依据牛油果的植物学类群及地理起源，通过分子表征结果对种质资源实现有效区分。此外，针对不同地理来源的未知类群种质资源，可通过其与同一聚类簇内已知基因型材料的比对，确定其所属的植物学类群或杂交种类型。