UV-B辐射诱导芒果叶片抗氧化响应研究

Characteristics of Antioxidant Responses of Mangifera indica Leaves by Enhanced UV-B Radiation

摘要:

为了解增强UV-B辐射诱导芒果叶片抗氧化响应的机制，以‘台农1号’芒果（Mangifera indica ‘Tainong No.1’）成年树为材料，以自然光为对照（CK），设置24和96 kJ/（m²·d）两个增强UV-B辐射处理水平，观测叶片生理生化指标的动态变化。结果表明，24 kJ/（m²·d）处理的芒果叶片MDA含量、相对电导率、净光合速率、抗氧化酶活性、多酚、Vc和芒果苷含量均与对照没有显著差异，而类黄酮和还原型GSH含量显著高于对照；而96 kJ/（m²·d）处理的芒果叶片MDA含量、相对电导率、抗氧化酶活性及多酚、类黄酮、还原型GSH、芒果苷等还原型保护成分的含量均显著高于对照，而净光合速率和Vc含量均显著低于对照。因此，24 kJ/（m²·d）UV-B辐射未引起‘台农1号’芒果成年树损伤，可能是通过提高类黄酮和还原型GSH的含量来清除活性氧自由基；96 kJ/（m²·d）处理则引起叶片活性氧损伤，但仍可能以两种机制减轻损伤，一是通过增强抗氧化酶活性和提高还原性成分含量来清除活性氧自由基，二是利用芒果苷、类黄酮和还原型GSH等成分吸收UV-B辐射。

Abstract:

In order to understand the mechanism of antioxidant responses of mango leaves to enhanced UV-B radiation, the adult trees of Mangifera indica ‘Tainong No. 1’ were treated with enhanced UV-B radiation of 24 and 96 kJ/(m²·d), respectively, with the natural sunlight as control (CK), and the dynamic changes in physiological and biochemical indexes were studied. The results showed that MDA content, relative electrical conductivity, net photosynthetic rate, antioxidant enzyme activities, contents of polyphenols, Vc and mangiferin in leaves treated with 24 kJ/(m²·d) UV-B were not significantly different from CK, while flavonoids and reduced GSH contents were significantly higher than CK. MDA content, relative electrical conductivity, antioxidant enzyme activities, polyphenols, flavonoids, reduced GSH, mangiferin and other reduced protective components were significantly higher than CK treated with 96 kJ/(m²·d) UV-B, while net photosynthetic rate and Vc content were significantly lower than CK. Therefore, the adult mango trees has not been injured under 24 kJ/(m²·d) UV-B, probably through increasing the content of flavonoids and reduced GSH to scavenge reactive oxygen species. The leaves were damaged by reactive oxygen species treated with 96 kJ/(m²·d) UV-B, but it could still reduce the damage by two mechanisms, at first, enhancing the activities of antioxidant enzymes, such as SOD, POD, CAT, and increasing the contents of reducing components, such as polyphenols, flavonoids, reduced GSH, Vc and mangiferin, at the second, mangiferin, flavonoids and reduced GSH could absorb UV-B radiation.