Molecular cloning and expression analysis of eight calcium-dependent protein kinase (CDPK) genes from banana (Musa acuminata L. AAA group, cv. Cavendish)

• We describe the eight CDPK genes cloned from Cavendish banana.
• MaCDPK3 gene may be a useful biomarker for drought, cold, and salinity stresses.
• MaCDPK2 and MaCDPK4 genes were sensitive to Foc TR4 infection.

The calcium-dependent protein kinase (CDPK) family is comprised of essential calcium sensors and responders that play important roles in response to various abiotic stresses in plants. In this study we describe the molecular characteristics of eight CDPK genes (MaCDPK1, MaCDPK2, MaCDPK3, MaCDPK4, MaCDPK5, MaCDPK6, MaCDPK7, and MaCDPK8) cloned from banana (Musa acuminate L. AAA group, cv. Cavendish) using a RACE-PCR-based strategy. The predicted molecular masses of these MaCDPKs ranged from 57.78 to 60.46 kDa and their pIs ranged from 5.89 to 8.97. At the amino acid level, they shared high sequence similarity with CDPKs in the banana DH-Pahang (AA group) genome. Phylogenetic analysis showed that the deduced amino acid sequences of MaCDPKs also had high similarity to CPKs of Arabidopsis. Expression analysis by semi-quantitative RT-PCR revealed that these genes were differently expressed in various tissues. In addition, their expression was regulated by various stress conditions, including exposure to signaling molecules, cold, salinity, drought, and Fusarium oxysporum f specialis(f. Sp) cubense Tropical Race 4 (Foc TR4) infection. MaCDPK3 responded to abiotic stresses, such as drought, cold, and salinity, while MaCDPK2 and MaCDPK4 were sensitive to Foc TR4. Our results indicate that MaCDPKs play important roles in both the development and stress responses of banana plantlets.