The transcriptional regulator JAZ8 interacts with the C2 protein from geminiviruses and limits the viral infection in Arabidopsis

Abstract

Jasmonates (JAs) are phytohormones that finely regulate critical biological processes, including plant development and defense. JASMONATE ZIM-DOMAIN (JAZ) proteins are crucial keeping JA-responsive genes in a repressed state. In the presence of JA-Ile, JAZ repressors are ubiquitinated and targeted for degradation by the ubiquitin/proteasome system, allowing the activation of the downstream transcription factors and, consequently, the activation of JA-responsive genes. A growing body of evidence has shown that JA signalling is crucial in defending against plant viruses and their insect vectors. Here, we describe the interaction of C2 proteins from two geminiviruses from the genus Begomovirus, tomato yellow curl Sardinia virus (TYLCSaV) and tomato yellow leaf curl virus (TYLCV), with the transcriptional repressor JAZ8 from Arabidopsis thaliana and its closest orthologue in tomato, SlJAZ9. Both JAZ and C2 proteins colocalize in the nucleus, forming discrete nuclear speckles. Overexpression of JAZ8 did not lead to altered responses to TYLCV infection; however, knock-down of JAZ8 favours the geminiviral infection in plants. Low levels of JAZ8 likely affect the viral infection specifically since JAZ8-silenced plants do not display developmental phenotypes nor present differences in their interaction with the viral insect vector. Our results show that JAZ8 interacts with geminiviral C2 proteins and exerts an anti-geminiviral effect.