外源甜菜碱对低温胁迫下香蕉内源甜菜碱合成的影响

摘要

After being treated with different concentration of BT, then stressed in the artificial bioclimatic chamber under 7℃ low temperature,the effects of exogenous betaine on the endogenous betaine synthesis in leaf and root of banana(Musa AAA Giant Cavendish cv.Brazil) were studied by measuring the content of endogenous betaine and the activities of the betaine key synthetase BADH in the leaves and roots of banana seedlings.The results indicated that after being treated with 10 mg/L BT for 16 h under 7℃,the activity of BADH and the content of endogenous betaine in leaves were increased with highly significant difference.Though the content of endogenous betaine in root was significantly higher than that in control which grows under normal circumstance,the activity of BADH was not significantly increased after being stressed for 24 h.Moreover,the endogenous betaine in leaf has significantly partial correlation with the BADH activity, and significantly correlation with the endogenous betaine in root, but no significantly correlation with the exogenous betaine.These results suggest that exogenous betaine could improve the synthesis and content of endogenous betaine in banana under low temperature stress.Both leaves and root have the ability to synthesize BT.%以巴西香蕉(Musa AAA Giant Cavendish cv.Brazil)幼苗为试验材料,用不同浓度外源甜菜碱(BT)预处理香蕉幼苗后,置于人工气候箱中模拟低温(7℃)胁迫,分别测定香蕉叶片和根系内源甜菜碱的含量和甜菜碱合成关键酶甜菜碱醛脱氢酶(BADH)活性,以探讨外源甜菜碱对香蕉叶片和根系内源甜菜碱合成的影响.结果显示:7℃低温胁迫16 h后,10 mg/L外源甜菜碱即可极显著提高香蕉幼苗叶片BADH活性,叶片内源BT含量也同步极显著增加,低温胁迫24h后根系内源甜菜碱的含量虽显著高于常温对照,其BADH活性却无显著提升.同时,香蕉幼苗叶片内源BT含量的积累与叶片BADH活性的提高具有显著正相关关系,与根系内源BT含量的增加呈极显著正相关关系,与外源BT浓度无显著相关性.研究表明,外源甜菜碱可促进低温胁迫下香蕉内源甜菜碱的合成和积累,叶片和根系均具有合成内源BT的能力.