CHRK1, a chitinase-related receptor-like kinase, plays a role in plant development and cytokinin homeostasis in tobacco.
CHRK1 encodes a receptor-like kinase that contains a chitinase-related sequence in the extracellular domain in Nicotiana tabacum. In this study, we showed that CHRK1 is mainly expressed in the shoot apex region including leaf primordia and young leaves, and germinating seedlings and vascular tissues, based on GUS activity of transgenic tobacco plants carrying the CHRK1 promoter-GUS fusion gene. Transgenic tobacco plants in which CHRK1 expression was suppressed exhibited pleiotrophic developmental abnormality, including formation of proliferating shooty calli from emerging seedlings and severely altered seedling development. At the cellular level, ectopic cell proliferation, reduced cell specificity, and aberrant chloroplast development were observed. The transgenic lines contained 3-fold higher level of cytokinin than the wild-type plants. Consistently, the transgenic seedlings exhibited a typical cytokinin response in the absence of hormone, such as deetiolation under the dark. Based on these results, we propose that CHRK1 is involved in a developmental signaling pathway regulating cell proliferation/differentiation and the endogenous cytokinin levels in tobacco.
Lee
Jeong Hee
JH
Laboratory of Plant Genomics, Korea Research Institute of Bioscience and Biotechnology, Yusong, Taejon 305-333, Korea.
Takei
Kentaro
K
Sakakibara
Hitoshi
H
Sun Cho
Hye
H
Kim
Do Myung
DM
Kim
Youn Sung
YS
Min
Sung Ran
SR
Kim
Woo Taek
WT
Sohn
Dae Young
DY
Lim
Yong Pyo
YP
Pai
Hyun-Sook
HS
D002455:Cell Division / Q000235:genetics / Q000502:physiology; D002736:Chloroplasts / Q000502:physiology / Q000648:ultrastructure; D018548:Cotyledon / Q000235:genetics / Q000254:growth & development / Q000648:ultrastructure; D003583:Cytokinins / Q000378:metabolism* / Q000494:pharmacology; D015870:Gene Expression; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism; D006651:Histocytochemistry; D006706:Homeostasis; D007210:Indoleacetic Acids / Q000494:pharmacology; D008854:Microscopy, Electron; D009154:Mutation; D010641:Phenotype; D010940:Plant Proteins / Q000235:genetics / Q000502:physiology*; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014026:Nicotiana / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism
D003583:Cytokinins; D007210:Indoleacetic Acids; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; C414309:CHRK1 protein, Nicotiana tabacum; D017346:Protein Serine-Threonine Kinases; D005966:Glucuronidase