Characteristics of SlCML39 , a Tomato Calmodulin-like Gene, and Its Negative Role in High Temperature Tolerance of Arabidopsis thaliana during Germination and Seedling Growth

Calmodulin-like (CML) proteins are primary calcium sensors and function in plant growth and response to stress stimuli. However, so far, the function of plant CML proteins, including tomato, is still unclear. Previously, it was found that a tomato ( ) CML, here named , was significantly induced by high temperature (HT) at transcription level, but its biological function is scarce. In this study, the characteristics of and its role in HT tolerance were studied. encodes a protein of 201 amino acids containing four EF hand motifs. Many cis-acting elements related to plant stress and hormone response appear in the promoter regions of . is mainly expressed in the root, stem, and leaf and can be regulated by HT, cold, drought, and salt stresses as well as ABA and H O . Furthermore, heterologous overexpression of reduces HT tolerance in at the germination and seedling growth stages. To better understand the molecular mechanism of , the downstream gene network regulated by under HT was analyzed by RNA-Seq. Interestingly, we found that many genes involved in stress responses as well as ABA signal pathway are down-regulated in the transgenic seedlings under HT stress, such as , , , and . Collectively, these data indicate that acts as an important negative regulator in response to HT stress, which might be mediated by the ABA signal pathway.