[Screening and identification of CKI1 upstream transcription regulators in Arabidopsis]

Arabidopsis CKI1 (cytokinin independent 1) is a histidine kinase protein involved in the two-component system, which can activate two-component signaling via the downstream histidine phospho-transfer proteins, playing the essential roles in central cell fate determination and development regulation in embryo sacs. However, studies on CKI1 upstream transcription regulators are still limited. In the present study, promoter activities with varying fragments were investigated, and CKI1 upstream transcription regulators were screened and identified by the yeast-one hybrid technique. Results indicated F5/R2 fragments located in the intron region showed promoter activities in embryo sacs, which is consistent with CKI1 full-length promoters. Then three tandem repeats of F5/R2 fragments were used to construct the bait expression vector, and Arabidopsis pistils were collected for cDNA library construction. Totally, 226 positive clones were screened by the yeast-one hybrid technique, 66 readable sequences were retrieved after removing sequences with low quality and redundant repeats, among which eight proteins could act as DNA-binding proteins. These results provided some important clues to study the molecular function of CKI1 in the transcription regulation network.