Effect of exogenous ALA on chilling resistance of Brazil banana seedlings under low temperature stress

[Objective]The current study was conducted to investigate the physiological effects and chilling injury mechanism of 5-aminolevulinic acid (ALA) on banana seedlings to provide basis for applying ALA in regulating chilling-resistance of banana seedling. [Method]After being sprayed with 1 mg/L ALA, Brazil banana seedlings were placed in an artificial climate box at low temperature stress(7℃) for 12, 24, 36 and 48 h, respectively Such parameters as plasmamembrane permeability, contents of chlorophyll (Chl.), MDA, soluble proteins and proline, SOD and POD activities of banana leaves were investigated during stress period, normal temperature, and low temperature stress of water were set as CK1 and CK2, respectively. [Result]Compared to CK2, under low temperature stress, Chl. content, activities of SOD and POD, contents of proline and soluble proteins in Brazil banana increased obviously, while plasmamembrane permeability, MDA content and generation rate of superoxide free radical(O2-) decreased. After 36 h stress, Chl. content, activities of SOD and POD in leaves increased by 90.6, 11.7 and 58.4%, respectively, while generation rate of O2-, plasmamembrane permeability and MDA content decreased by 85.3, 27.6 and 37.1%, respectively. [Conclusion]Under low-temperature stress, exogenous ALA can improve cold-resistance of Brazil banana seedlings by enhancing SOD and POD activities, reducing generation rate of O2-and plasmamembrane permeability, as well as increasing accumulation of proline and soluble protein and maintaining the stability of chlorophyll in leaves.