Cytokinin-induced immunity enhances rice blast resistance

Plant cytokinins (CKs) affect the outcome of plant-pathogen interactions. However, despite many examples their role remains ambiguous. In rice, CKs act synergistically with salicylic acid (SA) to induce defense genes in vitro but no effect on resistance against the blast fungus, Magnaporthe oryzae, was further observed in planta. Here, we demonstrate that exogenous CKs treatment triggers rice blast resistance in a molecule-, dose- and time-dependent manner by affecting defense- and CK-responsive genes. Similar enhanced resistance and gene expression patterns were confirmed in rice insertion mutant lines impaired for a gene that encodes a putative CK inactivation enzyme, supporting that endogenous CKs affect rice immunity. Together, our work brings insights on the CK-induced resistance of rice to M. oryzae.