Untersuchungen �ber die Manganverteilung zwischen Zellfraktionen aus Spinatbl�ttern und ihr Zusammenhang mit dem Manganhaushalt

Abstract

1. Spinach was harvested once a week, beginning five weeks after sowing. The leaves were divided into three categories, according to their height of insertion. For every category, Hill-activity and manganese content (by atomic absorption) were measured. The remaining leaf material was homogenised in distilled water or in a mixture of 0.6 M sucrose and 0.05 M Tris/maleate buffer, pH 7.8, and the homogenate was separated by differential centrifugation into two fractions: a green precipitate consisting mainly of chloroplast fragments and a yellow supernatant. Chloroplast fragments, isolated in sucrose medium, were washed with distilled water. Manganese and nitrogen content of the precipitate and the supernatant were determined, as was the chlorophyll concentration of the precipitate. 2. The manganese content in the old leaves and their fractions increased; nitrogen concentration, chlorophyll concentration, chlorophyll/nitrogen and chlorophyll/manganese ratios decreased. 3. The lowest inserted leaves and their fractions had a different chemical composition from the rest: they had a higher manganese and a lower nitrogen content. The chlorophyll/nitrogen ratio of the lamellae was also higher. 4. At the beginning, the lowest inserted leaves had the same manganese content as the seeds. Then the manganese concentration decreased slightly and increased again when leaf decomposition began. 5. We found a chlorophyll/manganese ratio of 104 molecules chlorophyll to 1 atom manganese. 6. Hill activity decreased with increasing age of the shoot. It seemed to be a function of the shoot age rather than the leaf age. 7. The manner of preparation had an effect on the chlorophyll/dry weight ratio, but not on the manganese/dry weight and nitrogen/dry weight ratios. Therefore the manganese/chlorophyll and the chlorophyll/nitrogen ratios depended on the manner of preparation.

Measurements of manganese in thylakoids of Sinapis alba grown under high-light and low-light conditions

“…This is in good agreement with the data of other authors [4,6,11,16] which give figures of between 1 and 2 Mn/100 Chl. Under these normal conditions, there was no Mn accumulation in the thylakoids.…”

“…Furthermore it was evident that the largest amount of manganese was always found in the oldest leaves and the smallest amount in the youngest. Similar results have been reported for spinach chloroplasts [9] and for the tissues of some other plants [16].…”