取样策略对SSR标记鉴别紫云英品种能力的影响

Effect of Sampling Strategy on Identification of Cultivars of Astragalus sinicus L. by SSR Marker

紫云英属于异花授粉植物,品种内个体基因型杂合,品种鉴定难度大。本研究以紫云英闽紫系列3个审定品种为材料,采用SSR标记进行取样策略对3个品种鉴别能力影响的研究。结果表明：（1）固定4对引物组合,从5~50进行梯度取样时,品种内的扩增位点总数、观测等位基因数趋于增多,但有效等位基因数、Shanon信息指数、遗传多样性指数增大到最大值后趋于下降,其中取样量为30时总体样品出现最大值;随着样品量的增加,品种间Nei氏遗传距离以及分子方差分析的品种间期望变异系数比例值（Phi PT）均呈减少趋势,但Phi PT值的置信度在增大;（2）固定品种的样品容量为30和50,再加入2对能扩增出在品种间形成频率差异的标记位点的SSR引物对,基于这6对SSR引物可以将参试的3个紫云英品种有效的区分,品种间期望变异系数比例值（Phi PT）提高且差异的置信度为极显著。主成分分析进一步表明：3个参试品种30个样品与50个样品的散布状况基本一致。对紫云英取样策略的研究表明：为提高对参试品种的鉴别能力,样品取样量以30株为宜,即达到较佳鉴别效果又降低分析成本。

Astragaluz sinicus L. is one of cross-pollinated plants with heterogeneity in cultivar population which results in difficulty for cuhivar identification. In this study,3 cultivars selected from Minzi cultivar series bred in Fujian have been analyzed by using SSR molecular marker and the effect of sampling strategy on cuhivar differentiation was investigated. The results showed that ： （ 1 ） When the primer combination was confirmed by 4 pairs and the sampling amount ranged from 5 to 50 in each cultivar,the amplified loci and the observed number of alleles tended to increase in the cultivar, but the effective number of alleles, Shannon index, and genetic diversity index tended to decline after reaching to a maximum as sampling amount was as much as 30 for total sample. With the increase of the amount of sample, the Nei＇ s genetic distance between cuhivars and the PhiPT value among population obtained from AMOVA reduced, but the confidence level of PhiPT was raised. （2） When the sample capacity was constant with either 30 or 50, and the primer number was increased to 6 pairs with the added 2 pairs of primer which could amplify the marking locus showing different frequency among the cultivars, the tested cultivars could be effectively identified because of the higher PhiPT value and more significant confidence level（ P 〈 0. 001 ）. The analysis of principal component further indicated that the distribution of samples from 3 tested cuhivars along principal component axis was similar between sampling amount of 30 and 50. This study of sampling strategy for Astragalus sinicus indicated that ：In order to enhance the ability in identification of cultivar of Astragalus sinicus L. , the optimum sampling amount was as much as 30 that could achieve the better effect for cultivar identification as well as reduce the cost in analysis.