Genomic Variations in the Tea Leafhopper Reveal the Basis of Its Adaptive Evolution

Tea green leafhopper(TGL),Empoasca onukii,is of biological and economic interest.Despite numerous studies,the mechanisms underlying its adaptation and evolution remain enigmatic.Here,we use previously untapped genome and population genetics approaches to examine how the pest adapted to different environmental variables and thus has expanded geographically.We complete a chromosome-level assembly and annotation of the E.onukii genome,showing notable expansions of gene families associated with adaptation to chemoreception and detoxification.Genomic signals indicating balancing selection highlight metabolic pathways involved in adaptation to a wide range of tea varieties grown across ecologically diverse regions.Patterns of genetic variations among 54 E.onukii samples unveil the population structure and evolutionary history across different tea-growing regions in China.Our results demonstrate that the genomic changes in key pathways,including those linked to metabolism,circadian rhythms,and immune system functions,may underlie the successful spread and adaptation of E.onukii.This work highlights the genetic and molecular basis underlying the evolutionary success of a species with broad economic impacts,and provides insights into insect adaptation to host plants,which will ultimately facilitate more sustainable pest management.

CRISPR/Cas9-based functional analysis of yellow gene in the diamondback moth,Plutella xylostella

The diamondback moth,Plutella xylostella(L.),is an economically important pest of cruciferous crops worldwide.This pest is notorious for rapid evolution of the resistance to diferent classes of insecticides,making it increasingly dificult to control.Genetics-based control approaches,through manipulation of target genes,have been reported as promising supplements or alternatives to traditional methods of pest management.Here we identified a gene of pigmentation(yellow)in P.xylostella,Pxyellow,which encodes 1674 bp complementary DNA sequence with four exons and three introns.Using the clustered regularly interspersed palindromic repeats(CRISPR)CRISPR-associated protein 9 system,we knocked out Pxyellow,targeting two sites in Exon III,to generate 272 chimeric mutants(57%of the CRISPR-treated individuals)with color-changed phenotypes of the Ist to 3rd instar larvae,pupae,and adults,indicating that Pxyellow plays an essential role in the body pigmentation of P xlostella.Fitness analysis revealed no significant difference in the oviposition of adults,the hatchability of eggs,and the weight of pupac between homozygous mutants and wildtypes,suggesting that Pxyellow is not directly involved in regulation of growth,development,or reproduction.This work advances our understanding of the genetic and insect science molecular basis for body pigmentation of P xylostella,and opens a wide avenue for development of the genctcally based pest control techniques using Pxyellow as a screening marker.