ICRISAT花生微核心种质资源SSR标记遗传多样性分析

【目的】评价ICRISAT花生微核心种质资源的遗传多样性水平,揭示ICRISAT花生微核心种质资源遗传多样性,验证传统植物学分类的可靠程度,为充分发掘、利用ICRISAT花生微核心种质资源提供必要信息。【方法】采用27对花生SSR引物,对ICRISAT微核心花生种质168份材料(来自世界五大洲42个国家)进行遗传多样性分析;利用NTSYS-pcV2.0软件进行主成分分析(PCA)并绘制三维空间聚类图;利用Popgene V1.32估算种质群间的Nei78遗传距离等参数并进行UPGMA聚类分析,采用MEGA3.1绘制种质群间聚类图。【结果】27对SSR引物共扩增出115条多态性条带,每对引物平均扩增出4.2930个等位变异,其中有效等位变异数2.7931,有效等位变异所占比重为65.49%;PM137、16C6、14H6、8D9和7G02等引物最为有效,其Shannon’s信息指数均在1.5以上,等位变异数5个以上,有效变异数3.7个以上。在多粒型群体中,来源于南美洲和印度种质资源的遗传多样性较低,来源于南美洲和非洲种质资源的遗传多样性较高;在珍珠豆型群体中,来源于北美洲种质资源的遗传多样性较低,来源于南美洲和非洲种质资源的遗传多样性较高;在普通型群体中,来源于北美洲种质资源的遗传多样性较低,来源于南美洲、美国和非洲种质资源的遗传多样性较高。来自南美洲的花生种质资源具有较高的遗传多样性,与花生起源于南美洲的结论一致。PCA分析,发现栽培种花生种质资源由4个差异明显的基因源构成,"hypogaea"包括普通型种质资源,"vulgaris"包括珍珠豆型种质资源,"fastigiata1"包括多粒型种质资源,"fastigiata2"包括多粒型种质资源。植物学分类单位间的Nei78遗传距离介于16.336—23.607cM,UPGMA聚类方法将花生属植物学分类单位聚成5个组群,"组群1"对应"hypogaea"基因源,"组群2"对应"vulgaris"基因源,"组群3"对应"fastigiata1"、"fastigiata2"基因源之和,"组群4"和"组群5"分别代表秘鲁型和赤道型基因源,聚类结果支持4个基因源的划分。【结论】ICRISAT花生微核心种质资源具有丰富的遗传多样性,不同来源的变种群间存在明显的遗传差异,并分化成4个基因源,研究结果部分支持栽培种花生传统的植物学分类体系。为拓宽花生育成品种的遗传基础,应充分发掘ICRISAT微核心种质各基因源的遗传潜力。

Analysis of Genetic Diversity in ICRISAT Mini Core Collection of Peanut (Arachis hypogaea L.) by SSR Markers

【Objective】 Assessing the genetic diversity of peanut mini core collection in ICRISAT and analyzing their genetic relationships among various groups of taxonomy, and verifying the fitness of traditionally botanical taxonomic system under cultivated peanut were carried out in the study, which could provide essential information for the exploration and utilization of ICRISAT peanut mini core collection. 【Method】 One hundred and sixty-eight peanut accessions from 42 counties of five continents were employed for SSR analysis using 27 polymorphic primer pairs in this study. Three-dimensional PCA graphs was conducted and drawn in NTSYS-pc V 2.0 statistical package. Parameters of genetic diversity (Nei78 genetic distances, et al.) were proceeded in Popgene V1.32 statistical package. The dendrogram of UPGMA method were drawn in MEGA3.1 statistical package. 【Result】 One hundred and fifteen polymorphic bands were amplified using 27 SSR primer pairs with unambiguous unique polymorphic bands. In average, 4.2930 alleles were observed, 65.49% of which was effective alleles (2.7931) in each SSR primer pair. PM137, 16C6, 14H6, 8D9 and 7G02 were the most effective SSR pairs, I value of which was over 1.5, alleles of which was over 5, effective alleles of which was over 3.7. SSR alleles were uniformly distributed among botanical taxon units in cultivated peanut. For ssp. fastigiata var. fastigiata, genetic diversity of germplasm from North America and India were lower, and that from South America showed higher. For ssp. fastigiata var. vulgaris, genetic diversity of germplasm from North America and Europe was lower, and that from South America and Africa was higher. For ssp. hypogaea var. hypogaea, genetic diversity of germplasm from North America was lower, and that from South America and Africa and USA was higher. So, genetic diversity of peanut germplasm from South America was abundant, which conformed that peanut originates in South America. Four taxonomic clusters were detected in ICRISAT mini core peanut collection by using PCA analysis. Gene pool “hypogaea” mainly consisted of var. hypogaea, gene pool “vulgaris” mainly consisted of var. vulgaris, while gene pool “fastigiata 1” and “fastigiata 2”mainly consisted of var. fastigiata. Nei’78 genetic distance among botanical taxon based groups of peanut genetic resources ranged from 16.336-23.607 cM. Five large cluster groups were identified based on the UPGMA dendrogram. Group 1 equals to “vulgaris” gene pool; Group 3 equals to “fastigiata 1”and “fastigiata 2” gene pool; and Group 4 equals to “hypogaea” gene pools; Group 2 and 5 stands for var. peruviana and var. aequatoriana respectively. The UPGMA clustering results generally support the PCA clustering results. 【Conclusion】 There were significant differences among most botanical groups in ICRISAT mini core collection, with clear separation of four gene pools for genetic diversity structure. The research results partially support the traditional botanical taxonomy under A. hypogaea L. In order to broaden the genetic bases of peanut breeding, the genetic potentials in the ICRISAT mini core collection should be thoroughly exploited.