野生二倍体香蕉(Musa acuminata,AA group)对冷害的生理响应

目的]评价低温对冷敏感香蕉品种Williams(Musa acuminata AAA cv.Williams)和耐冷香蕉品种野生二倍体(Musa acuminata,AA group)的影响,探讨香蕉耐冷机制,为香蕉抗冷性改良的遗传育种提供参考及香蕉生产提供理论指导.方法]经10、5和2℃低温胁迫处理24 h后,收集两个香蕉品种的叶片,测定其生理生化指标,调查叶片脂质过氧化水平丙二醛(MDA)、脯氨酸和不同色素含量及超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)活性].在正常生长条件下的两个香蕉品种植株设为对照.结果]经不同低温处理后,野生二倍体香蕉叶片中脯氨酸和不同色素含量均明显增加,而MDA含量降低;与对照相比,冷敏感香蕉品种Williams的脯氨酸和MDA含量相对较高,而不同色素含量无明显差异.低温条件下,两个不同香蕉品种叶片抗氧化酶活性表现有所不同.与对照相比,不同低温处理的野生香蕉种质叶片SOD活性出现明显下降趋势,而CAT和POD活性保持较高水平;但低温处理的Williams叶片SOD、CAT和POD活性变化与对照无明显差异.结论]野生二倍体香蕉的较高耐冷性可能与其生理生化指标的变化有关;野生二倍体香蕉具有较强的抗寒性,可作为筛选香蕉抗寒种质的中间材料.

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

Objective]In 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.Method]Leaf 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.Result]Under 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.Conclusion]The 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.