Cell-physiological Study on the Function of Root : (II) The tissue distribution of α-NA oxidizing activity root in relation to the TTC reducing activity in rice plant

Abstract

In this paper, the tissue distribution of α-naphthylamine(α-NA)oxidizing activity in rice root is reported. The tissue slice prepared from the various part of the root were incubated in the reagent mixture, 50ppm of α-NA in 0.015% of hydrogen peroxide solution, at about 30°C for 3hours. The α-NA oxidizing activity and its tissue distribution were determined qualitatively by the grade of coloration developed. Higher activity in α-NA oxidation was seen in the tissues, root cap, epidermis, and sclerenchyma of the cortex; medium one in the tissues, meristematic region of the root tip except dermatogen, and primordia; lower one in the tissues, parenchyma and central cylinder of both the matured and elongating regions of the root. Such a distributional pattern of α-NA oxidizing activity was quite the same as that of" peroxidase", which was reported before (6), in histochemical respect. Only the different point in the detection method between them is that α-NA is used as an oxidized agent (an acceptor of oxygen) in case of α-NA test instead of benzidine in case of peroxidase. Considering from these facts, it may be supposed that the enzyme involving in α-NA oxidation should be the same as histochemically so-called "peroxidase" itself. There was, generally, recognized a tendency that α-NA oxidizing activity was greater in the aged part rather than the younger part of root. Consequently it may be reasonable that the distributional pattern of α-NA oxidizing activity in root tissues quite differs from that of TTC reducing activity, whose high activity is usually appeared in the younger part of root as has been reported before (6)