The CBL-Interacting Protein Kinase NtCIPK23 Positively Regulates Seed Germination and Early Seedling Development in Tobacco ( L.).

CBL-interacting protein kinase (CIPK) family is a unique group of serine/threonine protein kinase family identified in plants. Among this family, and its homologs in some plants are taken as a notable group for their importance in ions transport and stress responses. However, there are limited reports on their roles in seedling growth and development, especially in plants. In this study, , a homolog of was cloned from . Expression analysis showed that is mainly expressed in the radicle, hypocotyl, and cotyledons of young tobacco seedlings. The transcriptional level of changes rapidly and spatiotemporally during seed germination and early seedling growth. To study the biological function of at these stages, the overexpressing and CRISPR/Cas9-mediated knock-out () tobacco lines were generated. Phenotype analysis indicated that knock-out of significantly delays seed germination and the appearance of green cotyledon of young tobacco seedling. Overexpression of promotes cotyledon expansion and hypocotyl elongation of young tobacco seedlings. The expression of in hypocotyl is strongly upregulated by darkness and inhibited under light, suggesting that a regulatory mechanism of light might underlie. Consistently, a more obvious difference in hypocotyl length among different tobacco materials was observed in the dark, compared to that under the light, indicating that the upregulation of contributes greatly to the hypocotyl elongation. Taken together, not only enhances tobacco seed germination, but also accelerate early seedling growth by promoting cotyledon greening rate, cotyledon expansion and hypocotyl elongation of young tobacco seedlings.