减弱UV-B辐射对烤烟生长发育过程中类黄酮和抗氧化酶系统的影响

Influence of Reduced Ultraviolet-B Radiation on Flavonoid and Antioxidase System in the Process of Tobacco Growth

在云南玉溪市通海县(102°45'E,24°07'N,海拔1 806 m)自然条件下,以不同厚度的聚乙烯薄膜和Mylar膜搭棚覆盖,在分别滤减25%(T1),50%(T2)和65%(T3)的UV-B辐射环境中盆栽种植烤烟K326,研究了不同UV-B辐射强度对K326烟叶类黄酮含量,过氧化氢酶(CAT),过氧化物酶(POD)和超氧化物歧化酶(SOD)活性动态变化及其相互关系的影响。结果表明:类黄酮主要在K326的旺长后期和衰老叶片中积累,且随UV-B辐射的减弱,含量逐渐降低,其中T3与对照相比差异显著(P<0.05)。在整个生育期中K326的SOD活性呈波动性变化,CAT变化为双峰型,POD活性则呈现逐渐上升的趋势,而各处理间酶活性差异不明显。在对照处理中类黄酮分别与POD和SOD表现为协同效应关系,在T1中与SOD则为互补效应,而T2和T3中类黄酮与酶活性相关性都较低。K326可能存在一个与叶龄有关的耐受UV-B辐射强度的阈值范围。

Tobacco plants were potted and treated under reduced 25%（T1）,50%（T2） and 65%（T3） of ambient solar UV-B radiation conditions obtained by covering with different thickness polyethylene and Mylar filters,respectively,during the growth period of tobacco in Tonghai（102°45′E,24°07′N,1806m above sea level） where the altitude is the highest in Yuxi Tobacco-growing Area.The effects of UV-B radiation on dynamic changes of flavonoid content and catalase（CAT）,peroxidase（POD） and superoxide dismutase（SOD） activities and their relationship in tobacco（K326） leaves were analyzed in the growing season of tobacco.The results showed that flavonoid accumulated in growing and typically in aging leaves.Accumulation of flavonoid in aging leaves decreased with the reducing of UV-B radiation,and it was significantly decreased in T3（P〈0.05）,compared with CK.SOD activities fluctuated and CAT activities changed with two-peak style,but POD activities increased during the experiment with no significances among treatments.Correlation analysis between flavonoid and antioxidases indicated that flavonoid content was jointed with POD and SOD activities in CK,whereas flavonoid content and SOD activity were complementary in T1 to prevent plants against UV-B.But no pronounced interrelations between flavonoid and antioxidases were observed in T2 and T3.It is implied that there might be a range of thresholds of UV-B intensities so that tobacco plants could endure.