Yue Xiaoyan, Zheng Xiaoyan, Zong Yu, Jiang Shuang, Hu Chunyun, Yu Peiyuan, Liu Guoqin, Cao Yufen, Hu Hongju, Teng Yuanwen
Department of Horticulture, Zhejiang University, Hangzhou, China.
The Key Laboratory of Horticultural Plant Growth, Development and Quality Improvement, Ministry of Agriculture of China, Hangzhou, China.
Front Plant Sci. 2018 May 7;9:591. doi: 10.3389/fpls.2018.00591. eCollection 2018.
Asian pear plays an important role in the world pear industry, accounting for over 70% of world total production volume. Commercial Asian pear production relies on four major pear cultivar groups, Japanese pear (JP), Chinese white pear (CWP), Chinese sand pear (CSP), and Ussurian pear (UP), but their origins remain controversial. We estimated the genetic diversity levels and structures in a large sample of existing local cultivars to investigate the origins of Asian pears using twenty-five genome-covering nuclear microsatellite (simple sequence repeats, nSSR) markers and two non-coding chloroplast DNA (cpDNA) regions (L-F and D-I). High levels of genetic diversity were detected for both nSSRs ( = 0.744) and cpDNAs (d = 0.792). The major variation was found within geographic populations of cultivated pear groups, demonstrating a close relationship among cultivar groups. CSPs showed a greater genetic diversity than CWPs and JPs, and lowest levels of genetic differentiation were detected among them. Phylogeographical analyses indicated that the CSP, CWP, and JP were derived from the same progenitor of in China. A dissemination route of cultivated estimated by approximate Bayesian computation suggested that cultivated from the Middle Yangtze River Valley area contributed the major genetic resources to the cultivars, excluding those of southwestern China. Three major genetic groups of cultivated were revealed using nSSRs and a Bayesian statistical inference: (a) JPs; (b) cultivars from South-Central China northward to northeastern China, covering the main pear production area in China; (c) cultivars from southwestern China to southeastern China, including Yunnan, Guizhou, Guangdong, Guangxi, and Fujian Provinces. This reflected the synergistic effects of ecogeographical factors and human selection during cultivar spread and improvement. The analyses indicated that UP cultivars might be originated from the interspecific hybridization of wild with cultivated . The combination of uniparental DNA sequences and nuclear markers give us a better understanding of origins and genetic relationships for Asian pear groups and will be beneficial for the future improvement of Asian pear cultivars.
亚洲梨在世界梨产业中发挥着重要作用，占世界总产量的70%以上。亚洲梨的商业化生产依赖于四个主要梨品种群，即日本梨（JP）、中国白梨（CWP）、中国砂梨（CSP）和秋子梨（UP），但其起源仍存在争议。我们使用25个覆盖基因组的核微卫星（简单序列重复，nSSR）标记和两个非编码叶绿体DNA（cpDNA）区域（L-F和D-I），对大量现有地方品种进行了遗传多样性水平和结构估计，以研究亚洲梨的起源。nSSR（ = 0.744）和cpDNA（d = 0.792）均检测到高水平的遗传多样性。主要变异存在于栽培梨品种群的地理种群内，表明品种群之间关系密切。CSPs的遗传多样性高于CWP和JP，且它们之间的遗传分化水平最低。系统地理学分析表明，CSP、CWP和JP均起源于中国的同一祖先。通过近似贝叶斯计算估计的栽培梨传播路线表明，长江中游流域地区的栽培梨为品种提供了主要遗传资源，不包括中国西南部的品种。使用nSSR和贝叶斯统计推断揭示了栽培梨的三个主要遗传群体：（a）JP；（b）从中国中南部向北到中国东北部的品种，覆盖了中国的主要梨产区；（c）从中国西南部到中国东南部的品种，包括云南、贵州、广东、广西和福建省。这反映了生态地理因素和人类选择在品种传播和改良过程中的协同作用。分析表明，UP品种可能起源于野生梨与栽培梨的种间杂交。单亲本DNA序列和核标记的结合使我们更好地了解了亚洲梨品种群的起源和遗传关系，并将有利于亚洲梨品种的未来改良。
