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.
Highlights
DNA methyltransferases (DNMTs) are a conserved family of enzymes that catalyze the methylation of cytosines in DNA, primarily in CpG dinucleotides
Since DNMT2 is involved in tRNA methylation, not DNA methylation, we focused on the DNMT1 for further study
Rapid amplification of Complementary DNA (cDNA) ends (RACE) was used to amplify the full-length transcripts of both genes, and we found that PsDnmt1B was longer than PsDnmt1A
Summary
DNA methyltransferases (DNMTs) are a conserved family of enzymes that catalyze the methylation of cytosines in DNA, primarily in CpG dinucleotides. DNMTs play essential roles in regulating gene expression, chromosome stability, cell differentiation, development, and genomic imprinting [1,2,3,4,5,6]. The function of DNMT1 in DNA maintenance is still poorly understood, and further studies are required to explore the roles of these duplicated genes [8,9,10]. The last type is the DNMT3 family, which mainly works de novo to methylate new CpG sites and to modify DNA in response to environmental effects [9]
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