Physiological responses of wild diploid banana(Musa acuminata, AA group)to chilling injury

ObjectiveIn the present study,the effects of low temperature on a cold-sensitive banana cultivar Williams(Mu-sa acuminata AAA cv. Williams)and a cold-tolerant cultivar wild diploid banana(M. acuminata,AA group)were estimated to explore the physiological mechanisms of cold-tolerant banana plants. The results could provide references for genetic breeding programs aiming at the improvement of banana chilling injury resistance and banana production.MethodLeaf samples of the two banana cultivars were collected after 10,5 and 2℃low temperature stress for 24 h to determine different physiological and biochemical indexes of the two banana cultivars. The level of lipid peroxidation,expressed as equivalents of malondialdehyde (MDA),proline,pigments contents,and the activities of superoxide dismutase(SOD),catalase(CAT)and peroxidase(POD) were investigated. Plants of the two cultivars grew under normal growth conditions were used as control.ResultUnder different low temperature treatments,an obvious increase in the contents of proline and pigments were found in wild diploid banana leaves,but MDA content decreased. In terms of Williams banana,high contents of proline and MDA were presented in leaves under low temperature condition,but no significant differences were found in contents of different pigments compared with con-trol. The antioxidative enzymes in the two cultivars also presented different responses under low temperature condition. SOD activity in wild diploid banana leaves showed obvious decrease trend as compared to control,but CAT and POD activities kept high levels in wild diploid banana leaves under low temparuture. Whereas the activities of SOD,CAT and POD in leaves of Wil-liams banana showed no significant differences between low temperature treatments and control.ConclusionThe strong cold-tolerance in wild diploid banana plants may be related to the changes of physiological and biochemical indexes;wild diploid ba-nana has stronger cold resistance and could be used as middle material for screening banana cold-resistant germplasms.