Plant virus suppression

During evolution, viruses have developed mechanisms to negate the RNA silencing pathway by expressing viral suppressors of RNA silencing (VSRs). The EU-funded MEVISP (Genetic, biochemical and cell biological mechanisms of virus silencing in plants) project made use of viral strains with impaired VSR function to investigate as yet unknown mechanisms of virus silencing.

To follow the elements of silencing pathways, the researchers used fluorescent protein tagged reporters and live cell microscopy. Immunological techniques also helped identify the location of key molecules.

Research results revealed that the major anti-viral protein, Dicer-like protein DCL4, is in the cytoplasm and its action is governed by alternative messenger RNA isoforms under epigenetic regulation. Furthermore, they observed that silencing components change their location during viral infection.

Work to develop a mutagenesis screen to discover new genes that mediate virus defence came across problems due to the choice of virus. A second virus was selected that was not prone to transgene instability in preliminary tests and work is in the final stages.

MEVISP researchers have collaborated with international labs and the plant lines/varieties generated will be released to the scientific community to expand work on virus silencing.

Besides opening up possibilities for new virus-resistant plants, the research will extend knowledge on gene regulation during seed development. Applications include enhancing food security through more sustainable agronomics and land usage.