484 / 2019-02-28 08:35:25

Unravelling the molecular mechanism underpinning the BAM1-mediated cell-to-cell spread of RNAi

virus,cell-to-cell movement,RNAi,BAM1,receptor complex

全体主题 > Signal Transduction

RNA interference (RNAi) is considered the main anti-viral defence in plants. One key feature of RNAi is that it can travel from cell to cell and over long distances through the vasculature. The mobile nature of RNAi is potentially crucial for its defensive function, since siRNA derived from invading viruses spread throughout the plant, immunizing distant tissues prior to the arrival of the pathogen. We identified a plasma membrane- and plasmodesmata-localized receptor-like kinase (RLK), BAM1 (BARELY ANY MERISTEM 1), as a positive regulator of the cell-to-cell spread of RNAi. In order to gain insight into this novel function of BAM1, we are defining which domains are essential to regulate the intercellular spread of RNAi; unexpectedly, our preliminary results indicate that the extracellular domain of this RLK is expendable for this process. In addition, we confirmed that several unrelated viral suppressor proteins that interfere with the cell-to-cell spread of RNAi associate indirectly with BAM1, suggesting the existence of a protein complex promoting the spread of RNAi and convergently targeted by viruses. In fact, we have already identified a member of the BAM1-containing complex, an RLK that we call BAR1 (for BAM1-associated RLK 1), which not only interacts with BAM1 but also recapitulates the BAM1-mediated expansion in the movement of RNAi when overexpressed. Altogether, our work sheds light on the molecular mechanisms regulating the BAM1-mediated RNAi movement.