High overexpression of CERES, a plant regulator of translation, induces different phenotypical defence responses during TuMV infection

12 Pág. Centro de Biotecnología y Genómica de Plantas
Mutations in the eukaryotic translation initiation factors eIF4E and eIF(iso)4E confer potyvirus resistance in a range of plant hosts. This supports the notion that, in addition to their role in translation of cellular mRNAs, eIF4E isoforms are also essential for the potyvirus cycle. CERES is a plant eIF4E- and eIF(iso)4E-binding protein that, through its binding to the eIF4Es, modulates translation initiation; however, its possible role in potyvirus resistance is unknown. In this article, we analyse if the ectopic expression of AtCERES is able to interfere with turnip mosaic virus replication in plants. Our results demonstrate that, during infection, the ectopic expression of CERES in Nicotiana benthamiana promotes the development of a mosaic phenotype when it is accumulated to moderate levels, but induces veinal necrosis when it is accumulated to higher levels. This necrotic process resembles a hypersensitive response (HR)-like response that occurs with different HR hallmarks. Remarkably, Arabidopsis plants inoculated with a virus clone that promotes high expression of CERES do not show signs of infection. These final phenotypical outcomes are independent of the capacity of CERES to bind to eIF4E. All these data suggest that CERES, most likely due to its leucine-rich repeat nature, could act as a resistance protein, able to promote a range of different defence responses when it is highly overexpressed from viral constructs.
This research has received funding from the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement n. 260468 to MMC and from the grant S2013-ABI2734 from CAM. In addition, this work has been financially supported by RTI2018-095946-B100 from MICIU and by the ‘Severo Ochoa Programme for Centres of Excellence in R&D’ from the Agencia Estatal de Investigación of Spain (grant SEV-2016-0672 [2017–2021]) to the CBGP. In the frame of this latter program, RT was supported with a postdoctoral contract.