Molecular Characterization of Two Highly Homologous Receptor-like Kinase Genes,RLK902andRKL1, inArabidopsis thaliana

Abstract

Receptor-like kinases (RLKs) constitute a large family of signal perception molecules. We characterized two highly homologous RLK genes, RLK902 and RKL1, in Arabidopsis. RLK902 and RKL1 showed a 75% amino acid sequence identity over their entire regions. In the RLK902 pro::GUS transgenic lines, GUS activity was strong in the root tips, lateral root primordia, stipules, and floral organ abscission zones, while the RKL1 promoter activity was dominant in the stomata cells, hydathodes and trichomes of young rosette leaves, and floral organ abscission zones. Neither the rlk902 mutant line, rkl1 mutant line nor rlk902/rkl1 double-knockout mutant line showed any significant phenotypes under normal growth conditions. These results suggest that RLK902 and RKL1 might mediate the signal transduction pathway in which at least one other complementary signaling pathway to these two RLKs might exist.

TheArabidopsisCold-Responsive Transcriptome and Its Regulation by ICE1

“…Among the cold-regulated RLKs, two RLKs have been studied in detail. The leucine-rich repeat transmembrane protein kinase, RKL1 (At1g48480), was predominantly expressed in stomatal cells and was induced by wounding, pathogen, and salicylic acid (Tarutani et al, 2004a(Tarutani et al, , 2004b. The RECEPTOR-LIKE PROTEIN KINASE 1 (RPK1) gene (At1g69270) has been reported to be induced by abscisic acid (ABA), dehydration, high salt, and cold (Hong et al, 1997).…”

Xanthomonas T3S Effector XopN Suppresses PAMP-Triggered Immunity and Interacts with a Tomato Atypical Receptor-Like Kinase and TFT1

“…Whereas nothing is known about this protein in tomato, the closest TARK1 homologs in Arabidopsis, AtRKL1 and AtRLK902, have been previously characterized in terms of their kinase activity and tissue-specific expression patterns (Tarutani et al, 2004b). Both proteins were reported to possess weak autophosphorylation activity in vitro, suggesting they might function as kinases in vivo (Tarutani et al, 2004a).…”

“…Both proteins were reported to possess weak autophosphorylation activity in vitro, suggesting they might function as kinases in vivo (Tarutani et al, 2004a). AtRKL1 is expressed at low levels in leaves and high levels in guard cells and hydathodes (Tarutani et al, 2004b), two portals used by bacteria, including Xanthomonas, to enter leaf tissue.…”

A High Content in Lipid-modified Peripheral Proteins and Integral Receptor Kinases Features in the Arabidopsis Plasma Membrane Proteome

“…The protein AtPepR1 (At1g73080) is also present; this new RLK has been shown to amplify defense gene signaling for the innate immune response against pathogens (82). Proteins RKL1 (At1g48480) and RLK902 (At3g17840), involved in stress response (83,84), were also identified. Identification of various subunits of functional PM complexes in the present proteome is further validation of the pertinence of our approach.…”