AUTHOR=Yu Chunmei , Ke Yongchao , Qin Jin , Huang Yunpeng , Zhao Yanchun , Liu Yu , Wei Hui , Liu Guoyuan , Lian Bolin , Chen Yanhong , Zhong Fei , Zhang Jian 

TITLE=Genome-wide identification of calcineurin B-like protein-interacting protein kinase gene family reveals members participating in abiotic stress in the ornamental woody plant Lagerstroemia indica

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.942217

DOI=10.3389/fpls.2022.942217

ISSN=1664-462X

ABSTRACT=<p>Calcineurin B-like protein-interacting protein kinases (CIPKs) play important roles in plant responses to stress. However, their function in the ornamental woody plant <italic>Lagerstroemia indica</italic> is remains unclear. In this study, the <italic>LiCIPK</italic> gene family was analyzed at the whole genome level. A total of 37 <italic>LiCIPKs</italic>, distributed across 17 chromosomes, were identified. Conserved motif analysis indicated that all LiCIPKs possess a protein kinase motif (S_TKc) and C-terminal regulatory motif (NAF), while seven LiCIPKs lack a protein phosphatase interaction (PPI) motif. 3D structure analysis further revealed that the N-terminal and C-terminal 3D-structure of 27 members are situated near to each other, while 4 members have a looser structure, and 6 members lack intact structures. The intra- and interspecies collinearity analysis, synonymous substitution rate (<italic>K</italic><sub><italic>s</italic></sub>) peaks of duplicated <italic>LiCIPKs</italic>, revealed that ∼80% of <italic>LiCIPKs</italic> were retained by the two whole genome duplication (WGD) events that occurred approximately 56.12–61.16 million year ago (MYA) and 16.24–26.34 MYA ago. The promoter of each <italic>LiCIPK</italic> contains a number of auxin, abscisic acid, gibberellic acid, salicylic acid, and drought, anaerobic, defense, stress, and wound responsive <italic>cis</italic>-elements. Of the 21 members that were successfully amplified by qPCR, 18 <italic>LiCIPKs</italic> exhibited different expression patterns under NaCl, mannitol, PEG8000, and ABA treatments. Given that <italic>LiCIPK30</italic>, the <italic>AtSOS2</italic> ortholog, responded to all four types of stress it was selected for functional verification. <italic>LiCIPK30</italic> complements the <italic>atsos2</italic> phenotype <italic>in vivo</italic>. 35S:LiCIPK-overexpressing lines exhibit increased leaf area increment, chlorophyll a and b content, reactive oxygen species scavenging enzyme activity, and expression of <italic>ABF3</italic> and <italic>RD22</italic>, while the degree of membrane lipid oxidation decreases under NaCl treatment compared to WT. The evolutionary history, and potential mechanism by which <italic>LiCIPK30</italic> may regulate plant tolerance to salt stress were also discussed. In summary, we identified <italic>LiCIPK</italic> members involved in abiotic stress and found that <italic>LiCIPK30</italic> transgenic Arabidopsis exhibits more salt and osmotic stress tolerance than WT. This research provides a theoretical foundation for further investigation into the function of <italic>LiCIPKs</italic>, and for mining gene resources to facilitate the cultivation and breeding of new <italic>L. indica</italic> varieties in coastal saline-alkali soil.</p>