Genome-wide Genetic Variation Of The Plutella Xylostella Populations In Kenya

The diamondback moth,Plutella xylostella(L.),is a worldwide insect pest,the environmental adaptability and insecticide resistance of which plays an important role in its regular outbreaks.Investigating the genetic basis of its adaptation thus is of importance in providing guidance for effective pest management.We collected 10 P.xylostella populations from Kenya(5 individuals from each population)at an elevation range of 40 to 2,000 meters.We used the genome resequencing technique to acquire genomic data,and then analyzed its genetic variation.Environmental adaption was also tested by using landscape genomic methods.Compared with other insect species,the P.xylostella populations in Kenya exhibited lower genetic diversity,with an range of 1.09×10-3?1.88×10-3,and were regardless of the sampling elevation.Differences in SNP number among populations were due to the sequencing depth,which further affected the nucleotide diversity.Linkage disequilibrium(LD)of each population decayed sharply with increasing physical distance(y2 decreased to half at a distance of around 20 bp),and is likely due to high recombination rate in P.xylostella.Principal component analysis(PCA),neighbor-joining phylogenetic tree and frappe were used to investigate the genetic structure of the P.xylostella populations.No distinct genetic clusters were found according to geographic locations,which were probablely resulted from frequent gene flow among P.xylostella populations in Kenya due to dispersal and human activities.Functional annotation analysis of SNPs was conducted based on gene ontology(GO)and Kyoto encyclopedia of genes and genomes(KEGG)databases.GO results indicated a majority of variations were enriched in genes involved in binding,catalytic activity,metabolism process and biosynthetic process.KEGG analysis showed that more genes related to carbohydrate metabolism,lipid metabolism and amino acid metabolism with variations.The GO enrichment of the genes were related to gene expression and receptor activity.Major gene terms in KEGG enrichment were related to nervous system of organismal systems,such as cholinergic synapse,GABAergic synapse and glutamatergic synapse.We then performed logistic regressions analysis between 276 environmental data and SNP variations by using Sam?ada.No outliers were detected base on the results,and indicated a negligible role of environmental forces(i.e.altitude,temperature,precipitation)in shaping genetic variation of P.xylostella.In this study,we analyzed the population genetic diversity,genetic structure and environmental adaptation of the P.xylostella populations in Kenya by using genome resequening data,which provided numerous genetic resources for the researches of local P.xylostella populations.The acquired variants will facilitate further studies on genetic basis of insecticide resistant as well as environmental adaptation,and support the potential management strategies.