보리와 옥수수 잎의 생소 , 단백질 함량 및 광계 (光系) 2 활성에 미치는 SO2 의 영향 = Effects of Sulfur Dioxide on Pigments , Protein Content and Photosystem 2 Activity of Barley and Corn Leaves

다국어 초록 (Multilingual Abstract)

This investigation was carried out to clarify the changes of pigments and soluble protein, and photosystem Ⅲ activity in the leaves of barley (SO_2-sensitive) and corn (SO_2-resistant) seedlings induced by the SO_2 fumigation (10, 50ppm). The pH changes of the leaf extract, the content of sulfite and sulfate, the activities of catalase, peroxidase, and polyphenoloxidase were compared in the leaves of barley and corn seedlings induced by SO_2 fumigation. The results are summarized as follows; An appreciable effect of pH change of leaf extract by SO_2 fumigation was observed in barley leaves (pH 6.10 to 5.18), but only a small change occurred in corn leaves (pH 5.66 to 5.50). Ths same pattern of pH changes was recorded when the solution of 0.2N HCl was added to leaf extract, providing lower buffering capacity of the barley leaves than corn leaves. After 2 hours of exposure to 10ppm SO_2, the contents of SO^2-_3 and SO^2-_4 were increased in barley leaves, while only SO^2-_4 increased in corn leaves. After fumigation with 10ppm SO_2 for 2 hours, barley leaves showed significant decreases in activities of caralase, to 17% peroxidase, to 58%, and polyphenoloxidase, to 88%. Corn leaves showed increases in activities of peroxidase, to 136%, and polyphenoloxidase, to 128%. Absorption spectra of pigments obtained from SO_2-fumigated leaves were gradually decreased with the fumigation time increases, but the decrease was more significant in barley leaves. Fumigation with 50ppm SO_2 for 2 hours induced the greatest decomposition in carotenoid, followed by chlorophyⅡ a and then chlorophyⅡ b in barley leaves. The ratio of chlorophyⅡa/b was decreased from 4.1 to 3.6 in barley leaves, but in corn leaves it was maintained almost a constant level (4.9-4.8). The rate of decomposition of chlorophyⅡ and carotenoid in corn leaves was very slow than those in the barley leaves. Fumigation with 50 ppm SO_2 for 2 hours, decreased the protein content of barley leaves to 59%, and that of corn leaves to 89%, and the extent of decrease in protein content was greater than that of pigments in barley and corn leaves. The rate of DCIP(dichlorophenol indophenol) photoreduction in SO_2-fumigated leaves was decreased to 18 and 67% in barley and corn leaves, respectively. However, DCIP photoreduction was considerably recovered about 32 and 92% with the addition of DPC(diphenylcarbazide) as an exogenous electron donor in barley and corn leaves, respectively.