Abstract
Possible links between plant defense responses and morphogenesis have been postulated, but their molecular nature remained unknown. We have previously reported that uni-1D mutation induces the up-regulation of the Pathogenesis-related (PR) gene via the accumulation of salicylic acid and evokes morphological defects, and that UNI encodes a CC-NB-LRR protein that belongs to the disease resistance (R) protein family. Here, we show that the uni-1D mutation stimulates cytokinin pathway. The uni-1D mutant exhibited up-regulation of cytokinin responsive genes ARR4, 5, 6 and accumulation of cytokinin. Overexpression of CKX1 (Cytokinin oxidase/dehydrogenase1) appeared to suppress ectopic meristem formation and up-regulation of PR-1 in the uni-1D mutant. In addition, the rin4 knock-down mutation which causes the constitutive activation of R protein RPS2, induced an up-regulation of ARR5 and morphological defects similar to the uni-1D mutation. From these data, we propose that the modification of cytokinin pathway might be involved in some R protein-mediated responses.
