Functional characterization of NtCEF1, an AP2/EREBP-type transcriptional activator highly expressed in tobacco callus.

Using PCR-select cDNA subtraction, we identified the genes that are predominantly expressed in the shooty callus induced by suppression of the CHRK1 receptor-like kinase gene. One of the identified genes encoded a novel AP2/EREBP-type transcription factor, and it was highly expressed in various types of tobacco callus including the CHRK1 transgenic callus, hence designated as Nicotiana tabacum Callus-Expressing Factor 1 NtCEF1. The NtCEF1-GFP fusion protein was localized in the nucleus.

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.

CHRK1, a chitinase-related receptor-like kinase, interacts with NtPUB4, an armadillo repeat protein, in tobacco.

CHRK1 is a receptor-like kinase containing a chitinase-related sequence in the extracellular domain in Nicotiana tabacum. The previous study indicated that CHRK1 plays a role in a signaling pathway regulating plant development and the endogenous cytokinin levels. In this study, we identified NtPUB4 as a CHRK1-interacting protein using yeast two-hybrid screening.