紫外辐射对绿豆幼苗的膜伤害

INFLUENCE OF ULTROVIOLET RADIATION ON LIPID PEROXIDATION AND MEMBRANE PERMEABILITY IN MUNG BEAN(PHASEOLUS RADITUS L.) SEEDLINGS

紫外辐射处理的绿豆幼苗，丙二醛含量和电解质渗漏率显著增加；超氧物歧化酶（ＳＯＤ）活性下降，脂氧合酶（ＬＯＸ）活性增强．这一结果表明紫外辐射降低了细胞内自由基的清除能力，膜脂过氧化作用加剧，从而使膜透性增大．植物的紫外辐射效应可能是由膜伤害介导的．

Mung bean(Phaseols raditus L.) seeds were pregerminated at 30℃ for 12h and then sown on horticultural vermiculite in glass pot. Mung beau seedlings received photosynthetically active radiation(PAR) from white fluorecent lamps on a 16 h light/8 h dark photoperiod at a constant temperature 23℃.UV radiation was supplied by UV-emitting fluorecent lamp (product of East China Electrical Group Co. Ltd.). Mung beau seedlings were grown for 5 days in the presence or absence of supplemenatl UV radiation. Plants were given supplemenal UV radiation for 6h each day from 9.15-15:15 o'clock. UV radiation was monitored by means of a portable UV-B radiometer(Model IL 1400, International Light Co. Ltd., Mass.USA), The irradiance of supplemental UV radiation was 0.26mW·cm-2.Lipid peroxidation in both hypocotyl and leaf as quantified by measurement of malondialdehyde(MDA), was increased by UV exposure. Increased electrolyte leakage of leaf tissue indicates the harmful effect of UV radiation on cell membrane systems.SOD activity based on protein content in both hypocotyl and leaf was decrased by UV radiation. The activity based on fresh weight had the same trend (data not shown).Significant increase of LOX activities were observed in both hypocotyl and leaf of UV treated plants. These results indicate that membranes may be targets of UV damage in plants.