TMV-Cg coat protein stabilizes DELLA proteins and in turn negatively modulates salicylic acid-mediated defense pathway

M. C. RODRIGUEZ; G. CONTI; D. ZAVALLO; C. A. MANACORDA; S. ASURMENDI

Buenos Aires

Congreso; 32 New Phytologist Symposium: Plant interactions with other organisms: molecules, ecology and evolution; 2013

The New Phytologist Trust

Plant viral infections alter the defense regulatory network during the process of tissue invasion. Emerging evidence demonstrates that viruses disturb the defense regulatory pathways of plants by altering the balance of hormones. DELLA proteins have been reported to play a central role in hormone crosstalk, although their role in the modulation of hormone signaling during virus infections has not been reported. Here, we demonstrate that Tobacco Mosaic Virus-Cg coat protein (CgCP) suppresses the salicylic acid (SA) signaling pathway without altering defense hormone levels. In parallel, we observed that expression of CgCP reduces plant growth and delays the timing of floral transition. Quantitative RT-PCR analysis of DELLA target genes showed that CgCP increases relative expression of the target genes, indicating that DELLA proteins modulate the transcriptional changes produced by CgCP expression. Analysis by fluorescence confocal microscopy confirmed that CgCP stabilizes DELLA accumulation in the presence of gibberellic acid (GA) and that DELLA proteins are also stabilized during TMV-Cg virus infections. Based on these results, we conclude that CgCP stabilizes DELLA proteins and in turn negatively regulate signaling pathways downstream of SA modulating the antiviral defense responses.