The Roles of DNA Methyltransferases 1 (DNMT1) in Regulating Sexual Dimorphism in the Cotton Mealybug, Phenacoccus solenopsis

Abstract

The cotton mealybug, Phenacoccus solenopsis, is an invasive pest that can cause massive damage to many host plants of agricultural importance. P. solenopsis is highly polyphagous, and shows extreme sexual dimorphism between males and females. The functions of DNA methyltransferase (DNMT) enzymes in the cotton mealybug have not been well studied. Here, we carried out an investigation of DNMTs in cotton mealybug to study their roles in sexual dimorphism. We found that the cotton mealybug has two copies of PsDnmt1, but Dnmt3 is absent. We then amplified the full-length cDNAs of PsDnmt1A (2225 bp) and PsDnmt1B (2862 bp) using rapid amplification cDNA ends (RACE). Quantitative reverse transcriptase PCR shows that both PsDnmt1A and PsDnmt1B are highly expressed in adult males, while the expression of PsDnmt1B is 30-fold higher in gravid females than in virgin females. We knocked down PsDnmt1A and PsDnmt1B with small interfering RNAs (siRNAs), and both genes were successfully down-regulated after 24 h or 72 h in adult females and pupa (t-test, p < 0.05). Down-regulating the expression of these two DNMT genes led to offspring lethality and abnormal body color in adult females. Furthermore, the silencing of PsDnmt1B induced abnormal wing development in emerged adult males. Our results provide evidence that PsDnmt1 plays a crucial role in regulating sexual dimorphism in the cotton mealybug.

Fatty acyl-CoA reductase influences wax biosynthesis in the cotton mealybug, Phenacoccus solenopsis Tinsley

“…Both dsRNAs showed satisfactory RNAi efficiency (Fig. 4a ), similar to those obtained via other RNAi methods used in the cotton mealybug, such as siRNA microinjection 52 and direct dsRNA feeding 53 . Meanwhile, shared phenotypes produced by the two molecules further proved the same on-target effects for both of them.…”

Sex‐specific expression and DNA methylation in a species with extreme sexual dimorphism and paternal genome elimination

“…It is also suggested that DNA methylation may have a role in the recognition and silencing of paternally derived chromosomes in males in the process of PGE (Bongiorni et al, 1999; Buglia et al, 1999). Supporting the idea that DNA methylation may be involved in sexual dimorphism and PGE in mealybugs and other scale insects, two recent studies have identified sex‐biased expression of the DNA methyltransferase DNMT1 in adult Phenacoccus solenopsis (Omar et al, 2020) and Ericerus pela (Yang et al, 2015), with females showing considerably higher expression compared to males in both species.…”

“…Supporting the idea that DNA methylation may be involved in sexual dimorphism and PGE in mealybugs and other scale insects, two recent studies have identified sex-biased expression of the DNA methyltransferase DNMT1 in adult Phenacoccus solenopsis (Omar et al, 2020) and Ericerus pela (Yang et al, 2015), with females showing considerably higher expression compared to males in both species.…”

DNA methylation regulates Vip3Aa resistance in fall armyworm (Spodoptera frugiperda)

“…In our FAW DNA methylation map, the mCs were detected in CG, CHG, and CHH (H represents A, T, or G) contexts. The DNA methyltransferases 3 (DNMT3) catalyzes non-CG context methylation, but DNMT3 is lost in Lepidoptera, and CHH context methylation is not observed in Lepidoptera (Glastad et al, 2011;Omar et al, 2020). However, CHH methylation was identi ed in Bombyx mori (Lepidoptera:Bombycidae), albeit in an extremely small proportion (Li et al, 2020), and in the absence of DNMT3 (Gao et al, 2020).…”