A Novel Oxidoreductase ShSDH1 from Endophytic OsiSh-2 Activates Rice Immunity through DAMPs and Cell Wall Integrity Remodeling

The plant-endophyte symbiont can enhance plant defenses against diseases, but the regulatory mechanisms by which endophyte-mediated immune networks for disease resistance in host plants remain largely unexplored. Here, we identified and purified a novel immunity elicitor ShSDH1 from the endophyte Streptomyces hygroscopicus OsiSh-2.

ShSDH1 can trigger a series of immune responses in rice, enhancing its disease resistance through a priming strategy that mainly involves the regulation of the jasmonic acid-ethylene (JA/ET) signaling pathway. ShSDH1 was identified as a novel PQQ-dependent sugar dehydrogenase with oxidoreductase activity. Its ability to induce immune responses relies on its enzyme activity and specific functional domains (GSDH and CBM6) that contain a conserved catalytic residue H183.