Chilli leaf curl virus infection downregulates the expression of the genes encoding chloroplast proteins and stress-related proteins.

Virus infection alters the expression of several host genes involved in various cellular and biological processes in plants. Most of the studies performed till now have mainly focused on genes which are up-regulated and later projected them as probable stress tolerant/susceptible genes. Nevertheless, genes which are down-regulated during plant-virus interaction could also play a critical role on disease development as well as in combating the virus infection. Hence, to identify such down-regulated genes and pathway, we performed reverse suppression subtractive hybridization in Capsicum annuum var. Punjab Lal following Chilli leaf curl virus (ChiLCV) infection. The screening and further processing suggested that majority of the genes (approximately 35% ESTs) showed homology with the genes encoding chloroplast proteins and 16% genes involved in the biotic and abiotic stress response. Additionally, we identified several genes, functionally known to be involved in metabolic processes, protein synthesis and degradation, ribosomal proteins, energy production, DNA replication and transcription, and transporters. We also found 3% transcripts which did not show homology with any known genes. The redundancy analysis revealed the maximum percentage of chlorophyll a-b binding protein (15/96) and auxin-binding proteins (13/96). We developed a protein interactome network to characterise the relationships between proteins and pathway involved during the ChiLCV infection. We identified that the most of the interaction occurs either among the chloroplast proteins (Arabidopsis proteins interactive map) or biotic and abiotic stress responsive proteins (Solanum lycopersicum interactome). Taken together, our study provides the first transcriptome and protein interactome of the down-regulated genes during C. annuum-ChiLCV interaction. These resources could be exploited in deciphering the steps involved in the process of virus infection. © Prof. H.S. Srivastava Foundation for Science and Society 2019.