DNA Methylation Suppression by Bhendi Yellow Vein Mosaic Virus

Bhendi yellow vein mosaic virus (BYVMV) belongs to the monopartite begomovirus associated with the β satellite. As a single-stranded DNA (ssDNA) virus, it should be amenable to transcriptional and post-transcriptional gene silencing (TGS and PTGS). Previously, we had demonstrated C2, C4 and βC1 to be having different levels of influence on PTGS. Hence in the present study, a series of experiments such as agroinfiltration, chop-polymerase chain reaction (PCR), quantitative PCR (qPCR) and bisulfite next generation sequencing (NGS) were designed to analyse the involvement of BYVMV proteins on DNA methylation suppression. From the preliminary studies, we concluded that BYVMV genes were responsible for TGS suppression and C2, C4 genes from BYVMV were selected for further studies. Agroinfiltration experiments with mutant C2 and C4 partial tandem repeat (PTR) constructs of BYVMV have confirmed the role of C2 and C4 in DNA methylation impairment. The protoplast replication assay has shown that C4 was not an impediment for viral DNA replication and subsequent agroinfiltration studies with the C4 mutant BYVMV PTR construct have revealed the involvement of C4 in viral DNA movement

A translation proofreader of archaeal origin imparts multi-aldehyde stress tolerance to land plants

Aldehydes, being an integral part of carbon metabolism, energy generation, and signalling pathways, are ingrained in plant physiology. Land plants have developed intricate metabolic pathways which involve production of reactive aldehydes and its detoxification to survive harsh terrestrial environments. Here, we show that physiologically produced aldehydes, i.e., formaldehyde and methylglyoxal in addition to acetaldehyde, generate adducts with aminoacyl-tRNAs, a substrate for protein synthesis. Plants are unique in possessing two distinct chiral proofreading systems, D-aminoacyl-tRNA deacylase1 (DTD1) and DTD2, of bacterial and archaeal origins, respectively. Extensive biochemical analysis revealed that only archaeal DTD2 can remove the stable D-aminoacyl adducts on tRNA thereby shielding archaea and plants from these system-generated aldehydes. Using Arabidopsis as a model system, we have shown that the loss of DTD2 gene renders plants susceptible to these toxic aldehydes as they generate stable alkyl modification on D-aminoacyl-tRNAs, which are recycled only by DTD2. Bioinformatic analysis identifies the expansion of aldehyde metabolising repertoire in land plant ancestors which strongly correlates with the recruitment of archaeal DTD2. Finally, we demonstrate that the overexpression of DTD2 offers better protection against aldehydes than in wild type Arabidopsis highlighting its role as a multi-aldehyde detoxifier that can be explored as a transgenic crop development strategy