Abstract
We have been studying one of the receptor-like kinase (RLK) genes, 90-2-RLK, in which T-DNA was inserted in a mutant line 90-2. The phenotype of 90-2 does not show apparent difference from that of wild type, suggesting that other RLKs might possess redundant function with 90-2-RLK. Then this study is focused on RKL1,which shows highest homology with 90-2-RLK. As rkl1 knock-out lines did not show any distinguishable phenotype from WT, we generated 90-2/rkl1 double knock-out plants. These plants did not show distinguishable phenotypes from WT either at least under normal growth condition. RKL1 mRNA can be detected in all tissues tested by Northern analysis, and showed strong expression in inflorescence and roots. In RKL1-pro-GUS transgenic lines, GUS activity was detected in floral organ abscission zones, carpel apex, and guard cells of anthers, sepals, and stems. In leaves, GUS was expressed in vascular bundle and hydathode. Furthermore, GUS staining was observed in cutting site of stems and petioles. These results suggest that RKL1 is induced by environmental stress such as water loss or wounding. Some positive clones were identified by a yeast two-hybrid screen using the RKL1 kinase domain as a bait. Two of these clones were identical to those obtained in yeast two-hybrid using the 90-2-RLK kinase domain as a bait. This result suggests that 90-2-RLK and RKL1 have common biochemical functions.
