紫外光B辐射对菠菜和小白菜叶片氮代谢的影响

Effect of Ultraviolet B Radiation on Nitrogen Metabolism in Spinach and Chinese Cabbage Leaves

在室内用１３．０ｋＪｍ－２ｄａｙ－１的紫外光Ｂ（ＵＶ－Ｂ）照射菠菜“华菠一号”和小白菜“矮脚黄”，以研究ＵＶ－Ｂ对两品种叶片氮代谢的影响；对照为无ＵＶ－Ｂ照射。结果表明：ＵＶ－Ｂ辐射降低了菠菜和小白菜的单株叶鲜重，并使其叶片内的可溶性蛋白和氨基酸含量下降。随着ＵＶ－Ｂ处理时间的延长，其叶片内蛋白水解酶的活性增强，谷氨酰胺合成酶（ＧＳ）和谷氨酸脱氢酶（ＧＤＨ）的酶活性明显升高。ＵＶ－Ｂ辐射诱导菠菜和小白菜叶片内苯丙氨酸解氨酶（ＰＡＬ）活性迅速升高，并导致其体内吸收ＵＶ－Ｂ的类黄酮化合物大量积累。因此推测，经ＵＶ－Ｂ辐射后菠菜和小白菜叶片内的氮代谢向有利于类黄酮合成的方向进行，类黄酮的积累可能是植物抵御ＵＶ－Ｂ的一个共同效应。

Spinach cultivar“Huabo No.1”and Chinese cabbage cultivar“Aijiaohuang”were grown in an indoor environment treated with 0 and 13 0 kJ m -2 day -1 of ultraviolet B(UV B,280-320 nm)to study the effect of UV B radiation on nitrogen metabolism in the leaves of spinach and Chinese cabbage.CK had no UV B radiation The results showed that UV B radiation decreased the weight of fresh weight and the content of soluble protein and free amino acid.Under UV B treatment,the increase of proteinase activity and the remarkable rise of GS and GDH activity were also observed.UV B radiation promoted the expression of PAL and resulted in the accumulation of flavonoids in the leaves of spinach and Chinese cabbage.It was inferred that the process of nitrogen metabolism was promoted by UV B treatment to the direction of flavonoids synthesizing,the accumulation of flavonoids was perhaps a common response for plant to protect UV B damage.