紫云英(Astragalus siniucus L.)对重金属胁迫的响应

Response of Chinese Milkvetch (Astragalus siniucus L.) to heavy metals coercion.

为探明铜冶炼厂附近农田重金属污染对冬季绿肥作物的毒害作用,通过盆栽试验,研究了浙江富阳铜冶炼厂附近的铜、锌、铅等重金属离子混合污染的水稻土上,紫云英的生长,根、茎、叶、果各部位重金属积累量和细胞超微结构的变化.结果表明,在供试土壤重金属混合污染下,紫云英根系生长缓慢,主根细小、侧根稀少,根瘤生长受抑制;地上部分枝减少,长势矮小,叶片黄化,花期推迟.土壤中铜、锌、铅被紫云英吸收后主要分布于紫云英根部;根中铜含量明显高于锌和铅,茎、叶中锌含量最高,果中铜含量最低.透射电镜(TEM)观察结果表明,重金属混合污染主要毒害叶绿体、线粒体、细胞核等细胞器的超微结构,使叶绿体膨胀变形,基粒片层解体,外膜结构消失,类囊体模糊不清,腔内空泡化或形成大脂类;使线粒体变形、脊突膨胀或消失、外膜解体;使细胞核核膜破裂、核仁膨胀消失并与染色质凝集在一起.供试土壤重金属混合污染对紫云英各部位细胞的破坏程度为根>叶>茎.

Changes of growth morphology, heavy metals accumulation amount and cell ultrastructure of root leaf and fruit of Chinese Milkvetch in Cu2+、Zn2+、Pb2+ heavy metal ions polluted paddy soil near Fuyang copper smelter of Zhejiang Province were studied using pot-cultivation test, so as to ascertain the toxic damage of heavy metal pollution of farmland near the smelter on the winter green manure crops. Heavy metals pollution of the tested soil could cause shoot growth show, root few thin and small, root nodule growth inhibited, above-ground branch short and reduced, leaf yellow and flower deferred. After taken up by Chinese Milkvetch, Cu2+、Zn2+、Pb2+ were distributed mainly in root with Cu content markedly higher than that of Zn and Pb, Zn content highest in leaf and stem, Cu content lowest in legumen. The results of observation through TEM showed that the toxic damage from heavy metals pollution of the tested soil was mainly the ultrastructure of the organelle (chloroplast, mitochondria and cell nucleus), causing expansion of chloroplast. Outer membrane structure disappeared, thylakoid blurred, hollowing with big lipid appeared inside the cavity; mitochondria deformed, cristae swelled or disappeared, outside membrane disintegrated; cell nucleolus bursted in membrane, nucleolus swelled or disappeared and agglutinated with chromatin together. Each located cell of Chinese Milkvetch in the polluted soil sample was damaged in the order root>leaf>stem.