Effect of excessive Fe~(2+) on leaf cells ultrastructure of soybean

The effect of excessive Fe~(2+) on plant growth and physiological characters were studied in our previous research. For a further investigation on the poisoning mechanism Fe~(2+), the ultrastructure of the leave cells of Glycine max (L.) Merrill was observed in this paper. The change of ultrastructural under excessive Fe~(2+) stress for two soybean varieties, named as Zhechun No.3 and 1601 separately, was described. The results showed: with a increase of Fe~(2+) concentration, the ultrastructural damage on the Zhechun No. 3 leave cells unceasing aggravated; huge starch grains appeared in chloroplasts; granas became disordered; some cristae of mitochondria decreased or was chaos. As the results, the chloroplast and mitochondria membrane disrupted; and some fragments of membrane system were found in vacuoles of leaf cytoplasm. The plasmalemma folded entad forming wave shape. When leaf cells suffered low-middle degree Fe~(2+) poison, the concentration of Fe~(2+) being 100 mg/kg and 300 mg/kg, the chloroplast structure of 1601 was injured slightly. However, under high concentration Fe~(2+) poison, the accumulation of starch grains in the chloroplast, disruption of chloroplast membrane disrupted; disintegration of mitochondria cristae resulted in the vacuolization of mitochondria appeared int he leaf cells of 1601. The results indicated that: excessive Fe~(2+) could injure the membranous structures of cells, among which the injury on chloroplast and mitochondria was more seriouis. Excessive Fe~(2+) caused the accumulation of starch grains in the chloroplast of leaf cells. The leaf cells ultrastructure of two soybean varieties had different response to Fe~(2+) poison, Zhechun No.3 soybean was more sensitive to Fe~(2+).