Abstract
The CIPK (CBL-interacting protein kinase) kinase family in plants is a type of serine/threonine protein kinase family. The members of this family interact with the upstream CBL protein (Calcineurin B-like protein) to form the CBL-CIPK signal system, involved in regulating plant growth and development as well as stress response processes. Early research found that AtCIPK24 interacts with AtCBL4 and AtCBL10, respectively, to activate downstream target proteins to respond to high salt stress. Earlier in this study, NsylCIPK24a homologous to AtCIPK24 from Arabidopsis thaliana was obtained from Nicotiana sylvestris , but CBL family members interacting with NsylCIPK24a and its specific function are unclear. Therefore, a genome-wide prediction of CBL family members of N. sylvestris was carried out; Predicted NsylCBL genes were cloned by RT-PCR, and the analyses of gene structure, protein conserved domain and expression pattern were then conducted. The NsylCBL members interacting with NsylCIPK24a were screened by the yeast two-hybrid system. Results showed that there are 12 potential NsylCBL genes in N. sylvestris, and all of them were cloned successfully. Four members including NsylCBL4, NsylCBL5, NsylCBL9 and NsylCBL10 could interact with NsylCIPK24a in yeast. There might be some similar CBL-CIPK pathways in tobacco plants, compared with Arabidopsis. The study provides experimental data for the functional identification of NsylCIPK24a , and increases understanding of CBL-CIPK network in N. sylvestris.
Highlights
Plants have developed a complex signal network system during the long-term evolution
NsylCIPK24a homologous to AtCIPK24 from Arabidopsis thaliana was obtained from Nicotiana sylvestris, but Calcineurin B-like protein (CBL) family members interacting with NsylCIPK24a and its specific function are unclear
It was found that AtCBL10-AtCIPK24 complex phosphorylated the Arabidopsis NHX Na+/H+ antiporter (AtNHX) located on the vacuole membrane, so that excess Na+ in the cytoplasm was isolated into the vacuole, thereby reducing Na+ concentration in cytoplasm and toxic effect (Quan et al, 2007)
Summary
Plants have developed a complex signal network system during the long-term evolution. The CBL-CIPK signaling system plays an important role in plant growth and development and in responses to biotic/abiotic stresses (Mao et al, 2016; Sanyal et al, 2016). It was found that AtCBL10-AtCIPK24 complex phosphorylated the Arabidopsis NHX Na+/H+ antiporter (AtNHX) located on the vacuole membrane, so that excess Na+ in the cytoplasm was isolated into the vacuole, thereby reducing Na+ concentration in cytoplasm and toxic effect (Quan et al, 2007). In the early stage of our group, the homologous gene NsylCIPK24a of AtCIPK24 was cloned from N. sylvestris (Xu et al, 2018) On this basis, this study conducted a genome-wide prediction and related analysis of CBL families in N. sylvestris; cloned CBL genes in N. sylvestris, screened and obtained CBL protein interacting with NsylCIPK24a. This study provides experimental data for further analysis of the function of NsylCIPK24a and CBL-CIPK signaling pathway in tobacco
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