LcKRP, a cyclin-dependent kinase inhibitor from Lycium chinense, is involved in an ABA-dependent drought stress-signaling pathway

Kip-related proteins (KRPs) play a central role in the regulation of the cell cycle and differentiation through the modulation of cyclin-dependent kinases (CDKs) in plants. Until now, little has been done to explore the relationship between drought stress and the expression of KRP genes and we will investigate this link. Drought stress was imposed on 15 weeks old plants and these plants were maintained at 15 % soil moisture level for 4 weeks. The final leaf area, final cell number per leaf, the stomatal aperture and ABA content were studied under drought stress treatment. Quantitative Fluorescent PCR (QF-PCR) and semi-quantitative reverse transcriptase (RT)-PCR analysis were used to investigate the transcripts level of LcKRP gene under different treatment conditions. The LcKRP gene was expressed in all plant organs, with the highest detected in mature leaves. Its transcripts accumulated after abscisic acid (ABA) and drought treatments, but reduced by the topical administration of abamine SG, an inhibitor of ABA biosynthesis. Leaf ABA content was of the similar trend with LcKRP transcript expression induced by drought stress in L. chinense. The LcKRP gene induced in drought stress, might be considered a good candidate to link between leaf repressed cell cycle activity and drought stress stimuli.