基于线粒体CO Ⅰ和CO Ⅱ基因的5种不同寄主植物西花蓟马种群遗传多样性研究

摘要

西花蓟马Frankliniella occidentalis(Pergande)是一种分布广、危害大的世界性检疫害虫.本研究旨在探讨田间常见5种寄主植物上的西花蓟马种群的寄主专化性和遗传多样性.以采自甘肃、宁夏的辣椒、茄子、蜀葵、月季、美人蕉等5种寄主植物上的西花蓟马为对象,以线粒体CO Ⅰ和CO Ⅱ基因为靶标,应用Arlequin 3.5软件进行种群遗传多样性、遗传分化、基因流水平及分子变异分析,以MEGA 7.0和Network 5.0软件分别构建单倍型系统发育树和中接网状树.结果显示,当以mtDNA CO Ⅰ和CO Ⅱ基因为靶标时,分别检测到13种和12种单倍型,其中单倍型H_1和H_2为优势单倍型;辣椒和茄子上的单倍型数量只有3种(CO Ⅰ基因)或2种(CO Ⅱ基因),而蜀葵、月季和美人蕉上的单倍型数量比较多,为7～9种(CO Ⅰ基因)或8～9种(CO Ⅱ基因);辣椒和茄子上的种群单倍型种类、单倍型多样性、核苷酸多样性和核苷酸平均差异数等均较蜀葵、月季和美人蕉上的种群低.CO Ⅰ和CO Ⅱ基因总寄主种群Fu'sFs检验结果分别为2.36和4.06,种群大小整体保持稳定;总寄主种群固定指数FST和基因流Nm分析表明,西花蓟马各寄主植物种群之间基因交流充分,尚未发生明显的遗传分化;AMOVA分析显示遗传变异主要来自种群内部;基于CO Ⅰ和CO Ⅱ基因序列的单倍型聚类和网状树都明显分为两支,分别对应西花蓟马的温室品系Glasshouse strain和羽扇豆品系Lupin strain;其中温室品系在所有寄主植物种群中均有发生,而羽扇豆品系的单倍型主要来自多年生的蜀葵、月季和美人蕉等植物,在辣椒和茄子上并无羽扇豆品系发生.研究结果对西花蓟马种群扩张机制探讨、遗传动态分析以及有效防控措施的制定具有一定指导意义.%Frankliniella occidentalis (Pergande) is a worldwide quarantine pest with wide distribution and can cause serious damage.This study aimed to evaluate the host specialization and genetic diversity among different host plant populations of F.occidentalis.In the present study,the mtDNA CO Ⅰ and CO Ⅱ were selected as molecular markers.Samples were collected from five host plant species,including Capsicum annuum,Solanum melongena,Althaea rosea,Rosa chinensis,and Canna indica in Gansu and Ningxia provinces.The genetic diversity,genetic differentiation,gene flow and molecular variance (AMOVA) were analyzed by using the software Arlequin 3.5.Phylogenetic relationships and median-joining networks were inferred from MEGA 7.0 and Network 5.0,respectively.The results showed that 13 and 12 types of haplotype were detected when the CO Ⅰ and CO Ⅱ gene sequences analyzed,respectively,and H_1 and H_2 were the dominant haplotypes.Moreover,only 3 (CO Ⅰ) and 2 (COⅡ) types of haplotype were detected in C.annuum (LJ) and S.melongena populations,but 7-9 (CO Ⅰ) or 8-9 (CO Ⅱ) types were detected in A.rosea,R.chinensis or C.indica populations.Furthermore,the haplotype diversity (Hd),nucleotide diversity (πr) and average number of nucleotide difference (K) of C.annuum and S.melongena populations were all lower than those of A.rosea,R.chinensis and C.indica populations.Analyses of fixation index (FST) and gene flow (Nm) based on CO Ⅰ or CO Ⅱ gene suggested high level of gene flow and no obvious genetic differentiation among host populations of F.occidentalis.Analysis of molecular variance (AMOVA) indicated that the genetic variance was mainly attributes to variation within populations.The phylogenetic tree and haplotype network analyses based on haplotypes of CO Ⅰ and CO Ⅱ genes showed two clear genetic branches,corresponding to the glasshouse strain and lupin strain of F.occidentalis,respectively.The haplotypes standing for glasshouse strain happened on all host plants,while the haplotypes standing for lupin strain were from perennial plant species A.rosea,R.chinensis and C.indica,but not from C.annuum and S.melongena.The present results may help us understand the population expansion mechanism,analyze genetic dynamics and set up effective management measures of F.occidentalis.