Publication in Plant Physiology

While the majority of RNA viruses replicate in the cytoplasm of their host cells, some viral proteins travel through the cell nucleus to hijack cellular processes or block defence mechanisms for the benefit of the viruses. These aspects are well documented in animals, but in plants, the functions of viral proteins located in the nucleus are still obscure.

Work published in Plant Physiology by the teams of Véronique Brault from INRAE Colmar and Véronique Ziegler-Graff from IBMP Strasbourg reveals that the capsid proteins of the turnip yellows virus interact with ALY proteins responsible for the export of messenger RNA from the nucleus to the cytoplasm. The ALY proteins interact with the major and minor capsid proteins in vitro and in vivo, but only the major protein localises in the nucleus of infected cells. In the plant Arabidopsis thaliana, inhibition of expression of the four ALY genes resulted in significant virus multiplication increase. This suggests that ALY proteins are involved in antiviral defence. They could also play a proviral role by being a target of the virus to reduce the export of cellular messenger RNAs in favour of viral multiplication. A detailed understanding of the dual role of ALY proteins in the viral cycle will enable to conceive an antiviral resistance strategy based on modulating their expression in plants.