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Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay
Published on: May 3, 2018
Identification and Expression Analysis of the Cyclin-Dependent Kinase Inhibitor ICK/KRP Gene Family in Pepper
Tiantian Li1, Qingzhi Cui1, Zhuoxuan Wu1
1College of Horticulture, Hunan Agricultural University, Changsha 410128, China.
Background:
Cell division plays a crucial role in plant growth and development. Cyclin-dependent kinase inhibitors (ICK/KRP) negatively regulate the cell cycle, thereby affecting cell elongation and organ development. This study aimed to systematically identify and characterize the ICK/KRP gene family in pepper, and to explore their roles in growth, development, and stress responses.
Methods:
Bioinformatics approaches were used for genome-wide identification, chromosomal localization, collinearity analysis, sequence characterization, promoter element prediction, and tissue-specific expression profiling of pepper ICK genes. Phylogenetic analysis was performed with homologs from Arabidopsis, tomato, maize, and rice. Quantitative real-time PCR and virus-induced gene silencing (VIGS) were applied to validate gene expression patterns and gene function, respectively. Subcellular localization assays were also conducted.
Results:
A total of six ICK genes were identified in pepper. They were classified into three subfamilies and distributed on different chromosomes, with one pair showing evidence of duplication. All ICK/KRPs contain the conserved Motif 1 (amino acid sequence: KIPTTREIEEFFATAEKQQQRRFIEKYNFDPVNEKPL) and were predicted to localize to the nucleus. Promoter analysis revealed cis-acting elements associated with plant development, stress responses, and hormone signaling. Expression pattern analysis indicated tissue-specific divergence and significant induction/repression under temperature stress. qRT-PCR results were consistent with transcriptome data, and expression differences were observed in materials with different stigma lengths. Subcellular localization confirmed that Caz03g38750.1 and Caz12g03790.1 proteins localize to both the nucleus and plasma membrane. Silencing of CazICK1 significantly repressed stigma elongation and altered stigma morphogenesis.
Conclusions:
The six pepper ICK/KRP genes display distinct diversity in distribution, structure and expression, and function in plant growth, development and stress adaptation. This work not only lays a solid basis for exploring the cell cycle regulatory network of pepper and contributes to relevant theoretical research, but it also identifies key gene resources for improving stigma traits. It has great potential for application in molecular breeding to promote high yield and efficient hybrid seed production in pepper.
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