Identification and Functional Analysis of Tomato CIPK Gene Family

Abstract

The calcineurin B-like interacting protein kinase (CIPK) protein family is a critical protein family in plant signaling pathways mediated by Ca²⁺, playing a pivotal role in plant stress response and growth. However, to the best of our knowledge, no study of the tomato <i>CIPK</i> gene family in response to abiotic stress has been reported. In this study, 22 members of the tomato <i>CIPK</i> gene family were successfully identified by using a combination of bioinformatics techniques and molecular analyses. The expression level of each member of tomato <i>CIPK</i> gene family under abiotic stress (low temperature, high salt, drought treatment) was determined by qRT-PCR. Results indicated that tomato CIPK demonstrated different degrees of responding to various abiotic stresses, and changes in <i>SlCIPK1</i> and <i>SlCIPK8</i> expression level were relatively apparent. The results of qRT-PCR showed that expression levels of <i>SlCIPK1</i> increased significantly in early stages of cold stress, and the expression level of <i>SlCIPK8</i> increased significantly during the three treatments at different time points, implicating <i>Solanum lycopersicum</i> CIPK1(SlCIPK1) and <i>Solanum lycopersicum</i> CIPK8 (SlCIPK8) involvement in abiotic stress response. <i>SlCIPK1</i> and <i>SlCIPK8</i> were silenced using Virus-induced gene silencing (VIGS), and physiological indexes were detected by low temperature, drought, and high salt treatment. The results showed that plants silenced by <i>SlCIPK1</i> and <i>SlCIPK8</i> at the later stage of cold stress were significantly less resistant to cold than wild-type plants. <i>SlCIPK1</i> and <i>SlCIPK8</i> silenced plants had poor drought resistance, indicating a relationship between SlCIPK1 and SlCIPK8 with response to low temperature and drought resistance. This is the first study to uncover the nucleotide sequence for tomato CIPK family members and systematically study the changes of tomato CIPK family members under abiotic stress. Here, we investigate the CIPK family's response under abiotic stress providing understanding into the signal transduction pathway. This study provides a theoretical basis for elucidating the function of tomato <i>CIPK</i> at low temperature and its molecular mechanism of regulating low temperatures.