Fungal Small RNAs Suppress Plant Immunity by Hijacking Host RNA Interference Pathways

RNA on the Attack Plant microbial pathogens often work through protein effectors that are delivered into the plant cells to disrupt critical cellular functions. Weiberg et al. (p. 118 ; see the Perspective by Baulcombe ) have now found that small RNAs (sRNAs) of the fungus Botrytis cinerea can play a similar role. After fungal infection of tomato or Arabidopsis leaves, the plant cells contained a suite of fungal-derived sRNAs. Three sRNAs were found to bind to the plant's own Argonaute protein, thereby silencing the plant's fungal defense genes.