About event
You are cordially invited to attend two public lectures given by researchers from the Gregor Mendel Institute of Molecular Plant Biology, Vienna:
Marco Incarbone
A Hormone-activated Mobile RNAi Pathway Defends Plant Stem Cells from Virus Infection
Gabriele Bradamante
Live Imaging of Virus infection, Plant Recovery and Antiviral sRNAs Movement
Special guest:
Ortrun Mittelsten Scheid, Epigenetic Changes in Plants Research Group, Gregor Mendel Institute of Molecular Plant Biology in Vienna.
Most plant viruses are unable to infect shoot apical meristems, which contain stem cells that generate all above-ground tissues, including the germline, but knowledge on the underlying molecular mechanisms remains poor. We show that exclusion of TuMV from stem cells is actually preceded by virus entry and that RNAi establishes a multi-layered defense system. Synthesis by RDR1 of double-stranded RNA from TuMV RNA mediates virus stem cell exclusion through virus-derived siRNA (vsiRNA) that are active in stem cells. However, RDR1 is not expressed in these cells, suggesting remote action through a mobile signal. This mobile signal is either vsiRNAs or long double-stranded RNA, but it is not blocked upon siRNA sequestration.
TuMV infection increases accumulation of the hormone salicylic acid (SA) which is necessary for increased RDR1 expression and exclusion of TuMV from stem cells. A broader analysis revealed that virus species that activate SA are also excluded from stem cells, while species that do not are able to infect the stem cells/germline. In conclusion, we elucidate a pathway of great biological relevance, where activation of SA upon infection triggers the RDR1-dependent production of mobile RNAs which restrict virus proliferation and form a virus-free niche in this essential tissue.
