Investigating the role of the chromatin regulator LHP1 in defense against geminiviruses and its interplay with the geminivirus-encoded C3 protein

01/03/2023 to 28/02/2025

Geminiviruses have emerged as devastating pathogens causing huge losses in crops worldwide. Geminiviruses replicate their circular single stranded (ss) DNA genomes in the nuclei of plant cells through double stranded (ds) DNA intermediates that are wrapped around histones, forming minichromosomes. The geminiviral chromatin is subjected to epigenetic modifications, which have been implicated in the regulation of viral pathogenesis. However, our understanding of the plant-geminivirus epigenetic battlefield is still limited.

The host laboratory identified the LIKE HETEROCHROMATIN PROTEIN 1 (LHP1) protein, a Polycomb protein binding H3K27me3 with a function in transcriptional repression, as a direct interactor of the geminivirus Tomato yellow leaf curl virus (TYLCV) C3 protein. C3 is an enhancer of viral replication with a yet-to-be-described essential role for the infection. Further experiments have found that LHP1 plays an anti-geminiviral role in tomato and N. benthamiana. Strikingly, transcriptional analysis showed that C3 largely changes the transcriptional landscape of the host in the context of the virus infection. In this proposal, by using a multidisciplinary approach combining cell biology, molecular biology, protein biochemistry, and genetics, we aim to unravel the molecular and cellular mechanisms whereby LHP1 counters geminiviral pathogenesis, and the effect of its interaction with C3.

This project will expand our understanding of the epigenetic changes underlying the outcome of geminivirus-plant interactions, and provide insight into the role of LHP1 in the ongoing arms race of plant defense and viral counterdefense.