Protection of ultrastructure in chilling-stressed banana leaves by salicylic acid

Objective:Chilling tolerance of salicylic acid(SA) in banana seedlings(Musa acuminata cv.,Williams 8818) was investigated by changes in ultrastructure in this study.Methods:Light and electron microscope observation.Results:Pretreatment with 0.5 mmol/L SA under normal growth conditions(30/22 °C) by foliar spray and root irrigation resulted in many changes in ultrastructure of banana cells,such as cells separation from palisade parenchymas,the appearance of crevices in cell walls,the swelling of grana and stromal thylakoids,and a reduction in the number of starch granules.These results implied that SA treatment at 30/22 °C could be a type of stress.During 3 d of exposure to 7 °C chilling stress under low light,however,cell ultrastructure of SA-pretreated banana seedlings showed less deterioration than those of control seedlings(distilled water-pretreated).Conclusion:SA could provide some protection for cell structure of chilling-stressed banana seedling.