Abstract
AtPSKR1, an Arabidopsis LRR-RLK, identified by the homology with carrot phytosulfokine receptor interacts with PSK at a binding constant of 7.7 nM. We analyzed pskr1-1, a knockout mutant of AtPSKR1, to understand in planta function of PSK signaling. Almost no [3H]PSK binding activity was found in pskr1-1 membranes. The homozygous plants of pskr1-1 were morphologically indistinguishable from the wild-type but showed several specific phenotypes including (a) rapid loss of cellular potential to dedifferentiate in an age-dependent manner, (b) hyper-senescence upon ethylene treatment, (c) early senescence in detached leaves which was not blocked by cytokinin application and (d) accelerated SAG12 expression upon ethylene or dark treatments. Once cellular dedifferentiation proceeded, pskr1-1 callus proliferated normally and re-differentiated into shoots and roots irrespective of the age of the original tissues. These results reveal an intriguing link between PSK signaling and regulation of post-mitotic aging in plants.
