Identification of six mitogen-activated protein kinase (MAPK) genes in banana (Musa acuminata L. AAA group, cv. Cavendish) under infection of Fusarium Oxysporum f. sp cubense Tropical Race 4

Mitogen-activated protein kinases (MAPKs) play important roles in signal transduction pathways responding to various stresses. In this study, we described the molecular characteristics of six MAPK genes (MaMAPK1, MaMAPK2, MaMAPK3, MaMAPK4, MaMAPK5 and MaMAPK6) cloned from banana (Musa acuminate L. AAA group, cv. Cavendish) using a RACE-PCR-based strategy. The predicted molecular masses of these MAPKs ranged from 43.0 to 70.1 kDa and their pIs ranged from 5.67 to 9.32. At the amino acid level, they shared high sequence similarity with MAPKs in the banana DH-Pahang (AA group) genome. Phylogenetic analysis showed that the deduced amino acid sequences of MaMAPKs also had high similarity with MAPKs of other plant species. These genes were expressed in nearly all tissues using semi-quantitative RT-PCR. All of the six MaMAPKs were induced by signal molecules in banana seedlings, such as ABA, Ethephon, MeJA and SA. The gene expressions of MaMAPK1, MaMAPK2, MaMAPK3, MaMAPK5 and MaMAPK6 were induced in resistant cultivar of banana after being inoculated with Fusarium Oxysporum f specialis (f. Sp) cubense Tropical Race 4 (Foc TR4). Our results suggest that MaMAPKs play a key role in both the development of banana seedlings and banana resistance to Foc TR4.