Laura Redzich, Heinrich-Heine-Universität Düsseldorf

Interference of pathogens with regulatory networks for carbon allocation in rice

The bacteria Xanthomonas oryzae pv. oryzae (Xoo) are the causative agent of Bacterial Leaf Blight (BLB) on rice. BLB causes up to 70 % yield loss and threatens the food security and sovereignty of smallholder farmers in Asia and Africa. Xoo injects transcription-activator-like effectors (TALEs) by a Type-III-Secretion system into adjacent cells. Once TALEs are shuttled into the nucleus, the transcription of SugarsWill-Eventually-be-Exported-Transporters (SWEETs) is upregulated. Three members of the third clade of the SWEET family are targeted by Xoo and trigger sucrose secretion.  Whereas African Xoo stains use two SWEET inducing TALEs (TalC and TalF) both targeting SWEET14, Asian Xoo strains use a different set of TALEs, namely

PthXo1, PthXo2 and its variants, PthXo3 and AvrXa7 to induce SWEET11a, 13 and/or 14. Editing of the corresponding TALE binding element (EBE) in the promoter regions of the SWEET genes blocks the SWEET induction, and, remarkably, results in resistance to the infection of the otherwise susceptible rice cultivars. The key goal of my PhD project is to unravel the transcriptional regulations of SWEETs to enable the development of BLB broad spectrum resistant, climate resilient rice varieties.