Sex-specific transcription and DNA methylation landscapes of the Asian citrus psyllid, a vector of huanglongbing pathogens

Abstract

The relationship of DNA methylation and sex-biased gene expression is of high interest, it allows research into mechanisms of sexual dimorphism and the development of potential novel strategies for insect pest control. The Asian citrus psyllid, Diaphorina citri (Kuwayama), is a major vector for the causative agents of Huanglongbing (HLB), which presents an unparalleled challenge to citrus production worldwide. Here, we identify the X chromosome of D. citri and investigate differences in the transcription and DNA methylation landscapes between adult virgin males and females. We find a large number of male-biased genes on the autosomes and a depletion of such on the X chromosome. We have also characterised the methylome of D. citri, finding low genome-wide levels, which is unusual for an hemipteran species, as well as evidence for both promoter and TE methylation. Overall, DNA methylation profiles are similar between the sexes but with a small number of differentially methylated genes found to be involved in sex differentiation. There also appears to be no direct relationship between differential DNA methylation and differential gene expression. Our findings lay the groundwork for the development of novel epigenetic-based pest control methods, and given the similarity of the D. citri methylome to other insect species, these methods could be applicable across agricultural insect pests.

Antennae-abundant expression of candidate cytochrome P450 genes associated with odorant degradation in the asian citrus psyllid, Diaphorina citri

“…A colony of D. citri was collected in 2015 using field populations from Nankang District, Jiangxi ( Yu et al, 2022 ). The culture was continuously maintained on Murraya paniculata seedlings in insect rearing cages kept at 27–28°C and relative humidity of 60–65% with a 14:10 h light: dark photoperiod.…”

“…The sequencing data was filtered to obtain clean reads with SOAPnuke (v1.5.2) by removing low-quality reads (i.e., low-quality base ratio > 20%) and reads with adaptor sequences and/or unknown nucleotides (>5%). Clean reads were aligned to the reference genome [Diaci version 3.0 ( Hosmani et al, 2019 ; Yu et al, 2022 )] using HISAT2 (version 2.0.4). Transcriptome de novo assembly and functional annotation were conducted in BGI Company as described by Yi et al (2021) .…”

DNA methylation is associated with codon degeneracy in a species of bumblebee

“…Many of the studies exploring a role for DNA methylation in the generation of different phenotypes in social insects have focused on single-sex caste differences, although see Glastad et al (2016). However, recently DNA methylation has been strongly implicated in the generation of sex differences in some hemipteran bugs (Bain et al 2021, Mathers et al 2019, with other related species showing minimum sex-specific DNA methylation (Yu et al 2022). This highlights the importance of assessing individual species rather than relying on observations of related species.…”

Caste- and sex-specific DNA methylation in a bumblebee is associated with codon degeneracy

“…(2016). However, recently DNA methylation has been strongly implicated in the generation of sex differences in some hemipteran bugs (Bain et al ., 2021; Mathers et al ., 2019), with other related species showing minimum sex-specific DNA methylation (Yu et al ., 2022). This highlights the importance of assessing individual species rather than relying on observations of related species.…”

“…Many of the studies exploring a role for DNA methylation in the generation of di erent phenotypes in social insects have focused on single-sex caste di erences, although see Glastad et al (2016). However, recently DNA methylation has been strongly implicated in the generation of sex di erences in some hemipteran bugs (Bain et al, 2021;Mathers et al, 2019), with other related species showing minimum sex-specific DNA methylation (Yu et al, 2022). This highlights the importance of assessing individual species rather than relying on observations of related species.…”