Abstract: Influence of La on chloroplast ultrastructure of soybean(Glycine max) leaves under elevated ultraviolet-B radiation(UV-B,280-320 nm) was studied.The results showed that the thylakoid in the chloroplast was placed in an orderly arrangement and observational clearly,as soybean leaves were pretreated by La(Ⅲ).The UV-B stress led to a chaos arrangement of the thylakoid in the chloroplast,expand or even indiscoverable.The impact on the thylakoid by the high intensity UV-B radiation(T2) was bigger than that by the low intensity UV-B radiation(T1).However,La(Ⅲ) changed the spatial location of chloroplast in the cell under the condition of UV-B stress.Therefore,the destruction of the chloroplast membrane caused by UV-B stress was alleviated.Consequently,the arrangement of the thylakoid in the chloroplast became orderly and clearly.The effect of the alleviation by La(Ⅲ) under the low intensity UV-B radiation(T1) was better than that under the high intensity UV-B radiation(T2).

Key words: Lanthanum(La), Lanthanum(La), Ultraviolet-B radiation, Soybean Leaves, Chloroplast, Ultrastructure