覃美 肖京林 王晓霞 凌桂芝 唐新莲 黎晓峰

摘  要：本文揭示锰毒胁迫下甘蔗根分泌烟酰胺及其作用，为解决甘蔗锰毒问题提供依据。采用液质联用技术分离、鉴定甘蔗分泌物中的烟酰胺;采用水培试验方法，在培养液中添加烟酰胺研究烟酰胺对锰毒引起的甘蔗根伸长、胼胝质和活性氧积累及其相关酶活性等的影响。结果液质联用质谱图上显示，甘蔗根系分泌物中存在烟酰胺质谱峰，且锰胁迫条件下烟酰胺信号更强;锰毒胁迫下甘蔗根系伸长受阻、根系活力降低，根尖积累胼胝质，根系中过氧化氢、活性氧及丙二醛含量和超氧化歧化酶、氧化氢酶、抗坏血酸氧化物酶活性显著提高;在锰胁迫下添加于培养液中的烟酰胺显著降低或消除锰的上述影响。可见，过多的锰诱导甘蔗根系分泌烟酰胺，而烟酰胺显著抑制过多的锰对甘蔗生长及过氧化胁迫伤害。

关键词：甘蔗;锰毒;烟酰胺;作用

中图分类号：S566.1      文献标识码：A

Abstract： This study revealed the secretion of nicotinamide from sugarcane roots under the stress of manganese toxicity and its role， and provided a basis for solving the problem of manganese toxicity in sugarcane. The liquid-mass spectrometry was used to isolate and identify nicotinamide in sugarcane exudates. The effects of nicotinamide on root elongation， callose and reactive oxygen species accumulation， and related enzyme activity of sugarcane induced by manganese toxicity were studied by hydroponic experiments. There were nicotinamide mass spectrum peaks in sugarcane root exudates， and the nicotinamide signal was stronger under manganese stress. Under the stress， the root elongation of sugarcane was blocked and the root activity decreased， while the root tip accumulated callose， the contents of hydrogen peroxide， reactive oxygen species and malondialdehyde and the activity of superoxide dismutase， oxidase and ascorbate oxidase in the roots were significantly increased. Nicotinamide added to culture medium under manganese stress significantly reduced or eliminated the above effects of manganese. It can be seen that excessive manganese induces the secretion of nicotinamide from sugarcane roots， and nicotinamide significantly inhibits the damage of excessive manganese to sugarcane growth and peroxide stress.

Keywords： sugarcane; manganese toxicity; nicotinamide; effect

DOI： 10.3969/j.issn.1000-2561.2021.11.036

錳是成土矿物的成分，土壤中锰多以难溶性矿物态存在，但在酸性等条件下大量的锰溶解到土壤溶液中。植物吸收积累过多的锰后，植物酶系统和功能受到干扰，植物代谢紊乱，正常生长受阻[1-3];形成并积累大量的活性氧，导致膜脂过氧化，多酚氧化形成褐色的醌类物质，叶片组织形成褐斑坏死[2， 4];抑制叶绿素的合成，加速叶绿素的分解，破坏叶绿体结构，光合受阻，叶片黄化[5-7]。因此，锰毒是酸性土壤中作物生长的主要限制因子。……