Controlling plant diseases by blocking pathogen food supply chain

While plant pathogens rely on their hosts for nutrients, the specific way they take these nutrients remains unclear. Recently, Wang et al. discovered that the bacterial type III effector AvrBs2 acts as a xanthosan synthetase, facilitating the transformation of uridine 5'-diphosphate-α-D-galactose into a sugar phosphodiester known as bis-(1,6)-cyclic dimeric α-D-galactose-phosphate, or xanthosan. When xanthosan is released from the plant’s cytoplasm into the apoplastic space, Xanthomonas species absorb it via the XanT transporter and break it down with the XanP phosphodiesterase to use as a source of nutrition. Overexpression of XanP in rice blocks the nutrient supply for Xanthomonas oryzae pv. oryzicola ( Xoc ), making the crop resistant to bacterial leaf streak disease.