Änderungen der Peroxydase- und Katalasereaktion des Blattes während der Entwicklung

Schwarze, P.

doi:10.1007/bf01937854

Cited by 5 publications

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“…However, the values obtained for the photosynthetically mature leaves agree with estimates obtained by other methods. Cellular fractionation in non-aqueous medium (2, 11) of autotrophically-grown Euglena has shown that 65 to 75 % of the transketolase activity is localized in the chloroplast (27 (14), polyphenoloxidase (tea) (18), peroxidase and catalase (sunflower & tobacco) (22), amine oxidase (pea) (35), succinoxidase (tobacco) (17), oxidative phosphorylation (pea) (31), and pentose phosphate cycle enzymes (tobacco) (5). In some instances, there was a slight increase in activity at the time of early leaf expansion.…”

Section: Discussionmentioning

confidence: 99%

Photosynthetic & respiratory activities of growing pea leaves

Smillie¹

1962

Plant Physiol.

110

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It is well known that leaves of different ages show differences in their rates of photosynthesis and respiration and indeed a number of detailed studies have been conducted to follow the changes in photosynthetic and respiratory rates during leaf ontogeny. The cellular mechanisms controlling these changes are not understood, although it is known that they can be influenced by altering either the internal or external environment. Decreased photosynthetic or respiratory rates in leaves of certain ages may result from the inability of the leaf cells to fully utilize their potential enzymic capacity. Alternatively, such decreases Progress were used in the experiments described in this paper. Details of growth conditions, the characteristics of the selected leaves, and sampling methods have been described previously (32). For each experiment, five samples corresponding to different stages of leaf growth were harvested. The youngest leaves were detached from plants 5 days after seed germination. Subsequent samples were harvested from 7-, 9-, 12-, and 16-day-old plants, respectively.Harvesting was carried out between 10 and 11 AM. Leaf expansion was generally completed in the leaves removed from the 12-day-old plants.The photosynthesis of intact pea leaves was determined manometrically at 13.5 C by measuring the oxygen production during illumination (a correction was made for dark respiration). The CO9 concentration was maintained at 1 % by using a CO., buffer system (16). Details of the procedure used are described in an earlier publication (30). The respiration of pea leaves was determined similarly by measuring the oxygen uptake in the dark. Otherwise the conditions were the same as those used for the photosynthesis measurements. The light-dependent uptake of NaHC140, by pea leaves was measured as described by Smillie and Fuller (28).Leaf extracts were prepared as follows. Weighed samples of leaves were ground in 0.04 M tris (hydroxymethyl) aminomethane buffer (tris), pH 7.8, using a pestle and mortar. The ground leaf mixture was quantitatively transferred to a glass Ten Broeck hand model homogenizer and further ground to ensure complete cell breakage. The homogenate was centrifuged at 144,000 X g for 30 minutes and the clear supernatant fluid was assayed for enzymic activity. The preparations were carried out at 4 C and the assays at 23 C.

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