Celery latent virus, an unusual new member within the Potyviridae – Further analysis of genome expression and protein functions

• Applicant: Dr. Hanna Rose
• Subject Area: Plant Breeding and Plant Pathology
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 460522487

Celery latent virus (CeLV) is a unique member of the Potyviridae family and the only species in the genus Celavirus to date. It has genomic elements, such as a signal peptide, which to our knowledge has not yet been detected in this family. Furthermore, an additional open reading frame (ORF) in the 3' region of the genome is predicted. In addition, there is little evidence for the functions of genes and proteins in the N-terminal part of the polyprotein. Therefore, an important aim of this research project is the identification and characterization of the N-terminal localized proteins in the CeLV polyprotein, especially proteins with a protease function. For this purpose, partial clones of the CeLV full-length clone will be constructed containing different parts of the genome/polyprotein and expressed in a cell-free expression system. To determine the exact cleavage sites of potential proteases, the expressed proteins will be sequenced individually by tryptic digestion and subsequent mass spectrometry.Another focus of this project is the further characterization of the signal peptide and its function in the infection process. The aim is to investigate whether the signal peptide is essential for the infection of different test plants and whether it can be replaced by foreign peptides with the same function. Another aspect is to find out whether CeLV actually uses other potential start codons that could serve as alternative translation starts and thus produce proteins with different N-termini. Furthermore, the existence of the predicted PIPO is to be demonstrated by constructing knock-out mutants. Depending on the results of the in vitro translation of the N-terminus, individual proteins will be tested in a local silencing assay to identify the silencing suppressor. By the use of knock-out mutants of the ORF predicted in the 3'-terminal region of the genome, a possible involvement in the infection process shall be clarified. It is expected that the work on this new and unusual virus will possibly reveal new strategies for genome expression and polyprotein translation or processing in the Potyviridae.

• DFG Programme: Research Grants