Plant trichomes and a single gene GLABRA1 contribute to insect community composition on field-grown Arabidopsis thaliana

Background:Genetic variation in plants alters insect abundance and community structure in the field; however, little is known about the importance of a single gene among diverse plant genotypes. In this context,Arabidopsistrichomes provide an excellent system to discern the roles of natural variation and a key gene,GLABRA1, in shaping insect communities. In this study, we transplanted two independent glabrous mutants (gl1-1andgl1-2) and 17 natural accessions ofArabidopsis thalianato two localities in Switzerland and Japan.Results:Fifteen insect species inhabited plant accessions, with 10–30% broad-sense heritability of community indices being detected, such as species richness and diversity. The total abundance of leaf-chewing herbivores was negatively correlated with trichome density at both the field sites, while glucosinolates had variable effects on leaf chewers between the two sites. Interestingly, there was a parallel tendency for the abundance of leaf chewers to be higher ongl1-1andgl1-2than for their different parental accessions, Ler-1 and Col-0, respectively. Furthermore, the loss of function in theGLABRA1gene significantly decreased the resistance of plants to the two predominant chewers, flea beetles and turnip sawflies.Conclusions:Overall, our results indicate that insect community composition onA. thalianais heritable across two distant field sites, withGLABRA1playing a key role in altering the abundance of leaf-chewing herbivores. Given that such a trichome variation is widely observed in Brassicaceae plants, the present study exemplifies the community-wide impact of a single plant gene on crucifer-feeding insects in the field.