VPS9a activates the Rab5 GTPase ARA7 to confer distinct pre- and post-invasive plant innate immunity ($)

Fungal invasion exploits plant cell membrane trafficking components. For instance, plant immunity against fungi such as Vlumeria graminis f.sp. hordei (Bgh) is defined through two stages: pre- and post-invasive immunity. Nielsen et al. found that Vacuolar Protein Sorting 9a (VPS9a) acts as a guanine nucleotide exchange factor which activates the Rab5 GTPase family (ARA6, ARA7 and RHA1). Formation of Multi Vesicular Bodies (MVBs) and proper membrane targeting depend on Rab5 GTPases. This article sheds light on the role of VPS9a for both pre- and post-invasive immunity against Bgh and broadens our understanding about membrane trafficking during powdery mildew attack. The authors conclude, “We propose that VPS9a plays a conserved role in organizing cellular endomembrane trafficking, required for delivery of defense components in response to powdery mildew fungi.” Plant Cell 10.1105/tpc.16.00859