Role of viral pathogenicity determinants on trade-offs established during compatible RNA virus-plant interactions

Plant virus diseases in commercial crops constitute one of the main causes of losses in both, food production and its quality. This is particularly true in the current context of global trade and climate change, which favors the emergence of new viral disease outbreaks and more severe symptoms. On the other hand, in many instances plants can get beneficial trade-offs from compatible viral infections when under stress situations, such as drought, salinity, unusually high or low temperatures, or their exposure to pathogens. The global aim of this Project is the understanding of mechanisms and processes involved in compatible interactions between plants and RNA viruses, and of responses that are triggered in the host by these interactions, which can offer plants a better performance under abiotic or biotic stresses. In this regard, the functions of the so-called viral pathogenicity determinants appear fundamental to the outcome of plant-virus interactions and to that of the host with its surrounding, changing environment.

The experimental model will be potyviral HCPro, a suppressor of gene silencing also known to interfere with the ubiquitin-proteasome defense pathway. To achieve the overall goal the group will follow a two-pronged approach: on the plant side, identifying to what extent proteasome and gene silencing functions become altered during virus infection, their effect on the host´s gene expression profiles and metabolism, in cross-talks between these pathways, and in the response of the plant to environmental stresses. This work would mainly be performed at the whole plant and tissue levels. On the virus side, studying the way HCPro triggers these alterations in host gene expression, metabolism and defense responses. That is, identifying how this viral molecule operates. Assays on the viral protein molecular functions and its effects are performed mainly in vitro and in vivo at the cellular level. The knowledge thus acquired would be comprehensive, and could potentially contribute to the design of strategies to promote host outcomes that lead towards tolerance or resistance to abiotic or biotic stresses over those that lead to disease. This is, to our understanding,  a rather novel approach to the design of strategies that would allow a competitive and sustainable agri-food industry. The conclusions from this Project will significantly advance knowledge of viral diseases and will be of potential application to companies connected with seed plant production, protection and improvement.

Briefly, the Objectives proposed are the following:

Objective 1.  Role of the ubiquitin-proteasome system in the virulence induced by HCPro in a compatible interaction:  the relationship between proteasome and phytohormone signaling responses.

Objective 2.  The protein and nucleic acid functional interactome of HCPro in a compatible host and its effect on host processes: analysis in vivo and in planta.