Linking Histone Methylation States and hsp Transcriptional Regulation in Thermo-Tolerant and Thermo-Susceptible A. mellifera L. Subspecies in Response to Heat Stress

Abstract

Genetic and epigenetic responses to environmental cues of worker honeybees mediate hsp synthesis, a key mechanism to tolerate high ambient temperatures in Apis mellifera. In this study, the chromatin immunoprecipitation assay followed by qPCR were used to determine alterations in histone methylation states (H3K27me2, H3K27me3, H3K4me2, and H3K4me3) associated with hsp/hsc/trx in A. m. jemenetica (thermo-tolerant subspecies) and A. m. carnica (thermo-susceptible subspecies) after heat treatment. The results revealed significant changes in enrichment folds of histone methylation states associated with hsp/hsc/trx. Indeed, the enrichment of H3K27me2 decreased strongly in response to heat stress. Changes in histone methylation states were significantly higher in A. m. carnica samples compared to A. m. jemenitica samples. Our study provides a new perception on linking histone post-translational methylation as an epigenetic mechanism of gene regulation with hsp/hsc/trx in A. mellifera subspecies exposed to heat stress.