A CBL-interacting protein kinase, AcCIPK18, from Ananas comosus regulates tolerance to salt, drought, heat stress and Sclerotinia sclerotiorum infection in Arabidopsis

In plants, calcineurin B-like proteins (CBLs) and their interacting kinase, CBL-interacting protein kinases (CIPKs), perform essential roles in mediating responses to various extracellular cues, including biotic and abiotic stresses. Several CIPK genes have been functionally characterized in different plant species. However, to date, the functions of pineapple CIPKs have not been investigated, which limits their potential use in molecular breeding. Here we functionally characterized an AcCIPK18 of pineapple and verified its role in salt, drought, heat stresses and immunity. Bioinformatics studies and phylogenetic analysis showed that AcCIPK18 is homologous to CIPK6 of Arabidopsis. Expression analysis shows that AcCIPK18 gets induced by salt, osmotic, heat and ABA. Besides, the ectopic expression of AcCIPK18 increased tolerance to salt, drought and heat stress but displayed sensitivity against fungal infection in Arabidopsis. We found that overexpression of AcCIPK18 changes the ROS homeostasis by altering the expression of several ABA signaling genes. These results provide evidence for the involvement of AcCIPK18 in multiple stress responses and advocates that AcCIPK18 could be used as a potential candidate gene for improving tolerance against multiple abiotic stress.