烟蚜茧蜂基因组中微卫星分布特点及分子标记开发

为明确寄生性天敌烟蚜茧蜂Aphidius gifuensis基因组中的微卫星分布特点并开发其分子标记，基于烟蚜茧蜂基因组草图，利用生物信息学方法分析其微卫星的分布特点并开发微卫星位点，采用PCR技术对获得的位点进行验证，获得高分辨率的分子标记位点。结果表明，烟蚜茧蜂基因组中共有360 199个微卫星，平均分布密度为1 787.93个/Mb，单碱基微卫星数量最多，占微卫星总数的81.46%，其中片段短于20 bp的微卫星居多，而数量最多的是单碱基（A）_n，其次是二碱基的（AT）_n和（AC）_n，以及三碱基的（AAT）_n和（ATC）_n。选取设计的45对微卫星引物进行PCR扩增，其中有21对引物能稳定扩增出清晰的条带。基于烟蚜茧蜂山东泰安种群24个个体的遗传多样性检测结果显示，筛选出的21个微卫星位点的平均观测杂合度、期望杂合度和多态性信息含量分别为0.48、0.57和0.50，其中位点S6的多态性最低，多态性信息含量为0.04，另有4个位点S12、S20、S29和S35显著偏离哈迪-温伯格平衡。结合PCR验证结果和遗传多样性分析结果筛选和开发出16个烟蚜茧蜂的有效微卫星位点，可作为有效的分子标记用于烟蚜茧蜂种群遗传学研究。

Characterization of the distribution of microsatellites in the genome of the parasitoid Aphidius gifuensis and development of molecular markers

To explore the characteristics of microsatellites (also known as simple sequence repeats, SSRs) and develop molecular loci in the genome of endoparasitoid Aphidius gifuensis, an important parasitoid enemy, this study utilized bioinformatic methods to analyze the distribution features and develop microsatellite loci based on the draft genome. Using polymerase chain reaction (PCR), developed microsatellite loci were verified and loci with high definition remained. The results showed that 360 199 microsatellites were identified, with an average density of 1 787.93 microsatellites per Mb. Mononucleotide microsatellites were the most among all different types, occupying 81.46%. Microsatellites with the length shorter than 20 bp accounted for the most abundant type. Among these microsatellites, (A)_n was the most abundant type, followed by (AT)_n, (AC)_n, (AAT)_n and (ATC)_n. Forty-five primers were designed, 21 of which could amplify definite bands in all samples. Twenty-four individuals from a population collected from Taian, in Shandong were chose to explore the polymorphism. The mean observed heterozygosity (H_o), expected heterozygosity (H_e) and polymorphic information content (PIC) were 0.48, 0.57 and 0.50, respectively. The PIC value of S6 was smaller (0.04), and S12, S20, S29, S35 were significantly deviated from the Hardy-Weinberg equilibrium. In this study, 16 microsatellite loci for A. gifuensis were developed, providing the potential molecular markers for further population genetic studies of this species.