Zhu Shenlong, Niu Erli, Shi Ainong, Mou Beiquan
Institute of Crops and Nuclear Technology Utilization, Zhejiang Academy of Agricultural Sciences, Hangzhou, China.
Department of Horticulture, University of Arkansas, Fayetteville, AR, United States.
Front Genet. 2019 Aug 21;10:755. doi: 10.3389/fgene.2019.00755. eCollection 2019.
Olive ( L.) is a very important edible oil crop and has been cultivated for about 4,000 years in the Mediterranean area. Due to its nutritional and economic importance, researches on germplasm characterization received extensive attention. In this study, using the genotyping-by-sequencing (GBS) technology, we carried out genetic diversity analysis on 57 olive cultivars with different geographical origins. In total, 73,482 high-quality single-nucleotide polymorphisms (SNPs) with minor allele frequency (MAF) > 5%, call rate > 50%, and heterozygosity rate < 10% were obtained at the whole genome level. Genetic structure and phylogenetic analysis showed that the 57 olive cultivars could be classified into two groups (Group I and Group II). No clear geographical distributions of cultivars were observed generally between the two groups. The average nucleotide diversities (π) specific for Group I and Group II were 0.317 and 0.305. The fixation index ( ) between Group I and Group II was 0.033. In Group II, cultivars could be further divided into two subgroups (Group IIa and Group IIb), which seem to be associated with their fruit sizes. The five Chinese-bred cultivars were all clustered in Group II, showing a closer genetic relationship with those from the central Mediterranean region and limited genetic background. It is therefore necessary for Chinese olive breeding programs to incorporate other genetic basis by utilizing germplasm from the other regions particularly from the east Mediterranean region as breeding parents. The results showed that GBS is an effective marker choice for cultivar characterization and genetic diversity analysis in olive and will help us better understand the genetic backgrounds of the crop.
油橄榄（Olea europaea L.）是一种非常重要的食用油作物，在地中海地区已经种植了约4000年。由于其营养和经济重要性，种质特性研究受到了广泛关注。在本研究中，我们利用简化基因组测序（GBS）技术，对57个不同地理来源的油橄榄品种进行了遗传多样性分析。在全基因组水平上，共获得了73482个高质量单核苷酸多态性（SNP），其最小等位基因频率（MAF）>5%，检出率>50%，杂合率<10%。遗传结构和系统发育分析表明，57个油橄榄品种可分为两组（第一组和第二组）。两组之间一般未观察到品种明显的地理分布情况。第一组和第二组的平均核苷酸多样性（π）分别为0.317和0.305。第一组和第二组之间的固定指数（Fst）为0.033。在第二组中，品种可进一步分为两个亚组（第二组a和第二组b），这似乎与其果实大小有关。5个中国培育的品种都聚类在第二组，与地中海中部地区的品种显示出更密切的遗传关系，且遗传背景有限。因此，中国油橄榄育种计划有必要通过利用其他地区特别是东地中海地区的种质作为育种亲本，纳入其他遗传基础。结果表明，GBS是油橄榄品种鉴定和遗传多样性分析的有效标记选择，将有助于我们更好地了解该作物的遗传背景。
