Cold-inducible transcription factor, CaCBF, is associated with a homeodomain leucine zipper protein in hot pepper (Capsicum annuum L.)

摘要

C-Repeat/drought responsive element binding factor (CBF1/DREB1b) is a well known transcriptional activator that is induced at low temperature and in turn induces the CBF regulon (CBF-targeted genes). We have cloned and characterized two CBF1-like cDNAs, CaCBF1A and CaCBF1B, from hot pepper. CaCBF1A and CaCBF1B were not produced in response to mechanical wounding or abscisic acid but were induced by low-temperature stress at 4 C. When plants were returned to 25 C, their transcript levels of the CBF1-like genes decreased markedly within 40 min. Longterm exposure to chilling resulted in continuous expression of these genes. The critical temperature for induction of CaCBF1A was between 10 and 15 C. Low temperature led to its transcription in roots, stems, leaves, fruit without seeds, and apical meristems, and a monoclonal antibody against it revealed a significant increase in CaCBF1A protein by 4 h at 4 C. Two-hybrid screening led to the isolation of an homeodomain leucine zipper (HD-Zip) protein that interacts with CaCBF1B. Expression of HD-Zip was elevated by low temperature and drought.