An endoparasitoid wasp influences host DNA methylation

Area of Science:

• Insect biology
• Epigenetics
• Molecular biology

Background:

• Parasitism by endoparasitoid wasps significantly impacts host gene expression, immune function, and development.
• The precise mechanisms by which parasitism alters host gene expression on a genomic scale remain incompletely understood.
• This study investigates the epigenetic regulation by the endoparasitoid wasp Cotesia plutellae in its host, Plutella xylostella.

Purpose of the Study:

• To elucidate the role of DNA methylation in host gene expression changes during parasitism.
• To investigate the expression patterns of DNA methyltransferases (DNMTs), methyl-binding domain proteins (MBDs), and ten-eleven translation (TET) proteins in parasitized and non-parasitized hosts.
• To determine the functional consequences of altered DNA methylation on host immunity and development.

Main Methods:

• Analysis of DNA methylation intensity in parasitized (P) and non-parasitized (NP) Plutella xylostella larvae using restriction digestion.
• Quantitative assessment of DNMT-1, DNMT-2, MBDs, and TET gene expression levels via quantitative PCR.
• Experimental manipulation of DNA methylation using 5-aza-2'-deoxycytidine (AZA) treatment and RNA interference (RNAi) targeting DNMT-1 and DNMT-2.

Main Results:

• DNA methylation intensity was reduced in parasitized P. xylostella larvae, particularly at later parasitic stages.
• Expression levels of DNMT-1 and DNMT-2 were decreased in parasitized larvae, correlating with reduced DNA methylation.
• Parasitism suppressed the expression of TET and MBDs, while AZA treatment and DNMT-1/DNMT-2 RNAi mimicked adverse effects on hemocyte spreading and larval development.

Conclusions:

• Endoparasitoid wasp parasitism induces genome-wide epigenetic alterations in the host, primarily through the suppression of DNA methylation.
• The observed changes in DNA methylation machinery (DNMTs, TET, MBDs) are critical for mediating the host's altered gene expression and developmental trajectory.
• Epigenetic modifications represent a key strategy employed by endoparasitoids to manipulate host physiology for their own benefit.