利用分子标记数据逐步聚类取样构建甘蔗杂交品种核心种质库

摘要

Sugarcane hybrids are important breeding parent sources of commercial varieties. To use efficiently and evaluate the sugarcane hybrids conserved in National Nursery of Sugarcane Germplasm Resources (NNSGR), we selected a total of 161 ac-cessions of sugarcane hybrids including 136 accessions from the pre-core collection of sugarcane hybrids constructed previously and 25 accessions introduced recently for constructing a core collection. Using stepwise UPGMA clustering sampling approach with three kinds of genetic similarity coefficient calculated according to SSR molecular data, these accessions were further screened to form a core collection with random sampling strategy as control. We tested the quality of core collections using nine indices, including Nei’s diversity index, Shannon-Wiener diversity index, total band number, polymorphic band number, percent-age of polymorphic bands (PPB), variable rate of coefficient of variation (VR), coincidence rate of range (CR), variance differ-ence percentage (VD) and mean difference percentage (MD). The results showed that 161 sugarcane hybrids possessed abundant genetic diversity at 20 SSR loci, which amplified 294 bands with 290 polymorphic bands taking up a mean of 98.64%of total bands. According to three kinds of genetic similarity coefficient (Jaccard, SM, and Dice) and two sampling strategies, ultimately eight core collections were gained. In the quality evaluating of core collections, three indices including Shannon-Wiener diversity index, total band number and polymorphic band number, performed high identifying efficiency, but the rest presented low effi-ciency. The core collection constructed on the basis of Jaccard or Dice genetic similarity coefficient was higher in quality than others, which consisted of 107 sugarcane hybrids with 0.9785 in Nei’s diversity index and 4.1854 in Shannon-Wiener diversity index, and did not have significant difference in molecular diversity with total resource at P < 0.05, moreover, MD = 0.00%(<20.00%) and CR=94.32%(>80.00%). All the mentioned above indicated the core collection can represent completely the diversity level of total resource in agronomic traits and molecular markers, and will can provide crucial basis for evaluating and utilizing sugarcane hybrids, and mining elite genes.%甘蔗杂交品种是商业品种选育的重要亲本资源,为有效管理和评价这类资源,本研究使用 SSR 分子标记数据,依据不同相似性系数,采用逐步 UPGMA 聚类法对161份甘蔗杂交品种(136份来自前期构建的初级核心种质库和25份为新引入国家甘蔗种质资源圃的材料)构建核心种质库,以随机取样方法为对照。在核心种质库质量检测中,用Nei’s多样性指数、Shannon-Wiener多样性指数、总条带数、多态性条带数、多态性条带比例、变异系数符合率、极差符合率、方差差异百分率和均值差异百分率评价分析。结果表明,161份材料在20个SSR位点上具有丰富的多态性,获得294个条带,其中290个为多态性条带,平均多态性条带比例达98.64%；依据3种相似性系数(Jaccard、SM、Dice)和2种取样方法获得8个核心种质库,在核心种质库质量检测中Shannon-Wiener多样性指数、总条带数、多态性条带数表现出较高的检测效率,而其他指标相对较低,8个库中依据Jaccard或Dice相似性系数构建的核心种质库质量最优,该库由107份材料组成, Nei’s多样性指数(0.9785)和Shannon-Wiener多样性指数(4.1854)在P<0.05概率条件下与原库(分别为0.9801和4.4074)无显著差异,而且与原库的均值差异百分率为0(<20.00%),极差符合率为94.32%(>80.00%),对原库分子和农艺性状遗传多样性都具有较好的代表性,可为后续甘蔗杂交品种资源的准确评价、优异基因发掘和开发利用提供重要的前期基础。