Transgenic expression of TMV capsid and movement proteins modulate plant basal defense and biotic stress responses in Nicotiana tabacum.

CONTI, G; RODRIGUEZ MC; MANACORDA CA; ASURMENDI S

MOLECULAR PLANT-MICROBE INTERACTIONS

AMER PHYTOPATHOLOGICAL SOC

Año: 2012 vol. 25 p. 1370 - 1384

0894-0282

Plant viruses cause metabolic and physiological changes associated with symptomatic disease phenotypes. Symptoms involve direct and indirect effects, which result in disruption of host physiology. We used transgenic tobacco expressing a variant of Tobacco mosaic virus (TMV) coat protein (CPT42W) or movement protein (MP), and a hybrid line (MPxCPT42W) that co-expresses both proteins to study the plant response to individual viral proteins. Findings employing microarray analysis of MPxCPT42W plants and silenced mpxcpT42W* controls revealed that altered transcripts were mostly downregulated, suggesting a persistent shut-off due to MPxCPT42W expression. Next, we showed that MP triggered ROS accumulation, reduction of total ascorbate and expression of ROS scavenging genes. These effects were enhanced when both proteins were co-expressed. MP and MPxCPT42W plants showed increased levels of SA and SA-responsive gene expression. Furthermore, these effects were partially reproduced in N. benthamiana when GMP1 transcript was silenced. CPT42W seems to be playing a negative role in the defense response by reducing the expression of PR-1 and RDR-1. MP and MPxCPT42W transgenic expression promoted a recovery-like phenotype in TMV-RNA infections and enhanced susceptibility to Pseudomonas syringae and Sclerotinia sclerotiorum. The individual effects of viral proteins may reflect the ability of virus to balance its own virulence.