Identification and characterization of CBL and CIPK gene families in eggplant (Solanum melongena L.)

Eggplant (Solanum melongena L.) is an edible vegetable cultivated and consumed worldwide. But the production of eggplant is significantly limited by the soil salinization in greenhouse cultivation system. The main ions are Na+, Ca2+, Mg2+, K+, Cl-, and SO4 (2-) in the salty soils. Calcineurin B-like proteins (CBLs) are calcium sensors and control the affinities and activities of numerous ion transporters with CBL-interacting protein kinases (CIPKs). In this study, a total of 5 CBL and 15 CIPK genes from eggplant were identified first. The yeast two-hybrid (Y2H) assay and bimolecular fluorescence complementation (BiFC) assay demonstrated the interaction network between SmCBLs and SmCIPKs. Strikingly, some new CBL-CIPK complexes were found which have never been discovered in any other plant species. The expression level of each SmCBL or SmCIPK under 200 mM NaCl, low potassium (LK; 100 mu M), high Mg with 20 mM MgCl2 and MgSO4 stresses were examined by quantitative real-time PCR (qRT-PCR) assay and these CBL and CIPK genes were found to respond to the four ion stresses differently. Interestingly, the differential expression level of SmCIPK3, -24 or -25 to Mg2+ is higher than Na+, and Cl- is higher than SO4 (2-). In addition, different magnesium salt can induce different response mechanisms in eggplant. In summary, this study provides insight into the characterization of CBLs and CIPKs in eggplant. It may be used in a novel biotechnological breeding program strategy to create new eggplant cultivars, leading to enhance different ion tolerance.