Kakuzo Kitagishi

Chemical Forms, Mobility and Deposition of Silicon in Rice Plant

Abstract The study of chemical forms and physiological mobility of elements found in plants is always essential to establishing the roles of elements in plant life. Such information in combination with the results of growth experiments will lead to more. reliable conclusions on the physiological functions of elements.

HISTOCHEMISTRY OF SILICON IN RICE PLANT : III. The Presence of Cuticle-Silica Double Layer in the Epidermal Tissue

As seen in the previous paper1) the use of HF-etching method has added much information to the mode of silicon deposition in rice tissues. The results obtained cover a wide range from root to husk. However, the importance of silicon deposition in epidermis in relation to the resistance of plants to diseases or insect pests makes it desirable to continue further studies of the mode of silicon deposition in outer region of epidermis. The study of microstructure of epidermis in connection with silicon deposition will provide valuable information to the mechanism of resistance rice plant to blast disease, because penetration of the rice leaf by piricularia oryzae is ordinarily through the cuticle rather than via the stomata. It will be of importance also to the study of a possible role of silicon in water economy of rice plant as already suggested by the present authors.

HISTOCHEMISTRY OF SILICON IN RICE PLANT : II. Localization of Silicon within Rice Tissues.

Abstract As seen in the previous paper1) the use of HF-etching method has added much information to the mode of silicon deposition in rice tissues. The results obtained cover a wide range from root to husk. However, the importance of silicon deposition in epidermis in relation to the resistance of plants to diseases or insect pests makes it desirable to continue further studies of the mode of silicon deposition in outer region of epidermis. The study of microstructure of epidermis in connection with silicon deposition will provide valuable information to the mechanism of resistance rice plant to blast disease, because penetration of the rice leaf by piricularia oryzae is ordinarily through the cuticle rather than via the stomata. It will be of importance also to the study of a possible role of silicon in water economy of rice plant as already suggested by the present authors.

Role of siucon in rice nutrition

Abstract In spite of tremendous efforts by many plant physiologists, it still remains unsolved whether or not silicon is essential to higher plants. It is, however, generally accepted that some plant species markedly respond to silicon under some conditions and accordingly silicon is often described as a beneficial element.

Effects of Zinc Deficiency on the Nitrogen Metabolism of Meristematic Tissues of Rice Plants with Reference to Protein Synthesis

Zinc deficiency remarkably depressed the zinc concentrations in the meristematic tissues of rice plants. When the zinc concentration was decreased to a level of less than 100 ppm, disorders of the nitrogen metabolism appeared. Zinc deficiency severely depressed the production of proteins in meristematic tissues and brought about the accumulation of free amino acids and ami des (above all, asparagine, glutamine, and alanine). Two-dimensional separation patterns of proteins obtained by O’Parrell’s technique suggested that the composition of the proteins remained almost unchanged although their amount was remarkably reduced.

Effect of Zinc Deficiency on 80S Ribosome Content of Meristematic Tissues of Rice Plant

1. A convenient method was developed for the determination of 80S ribosome content using an analytical ultracentrifuge. 2. Zinc deficiency depressed the content of free 80S ribosomes in the meristematic tissues of rice plant, followed by reduced protein contents.

HISTOCHEMISTRY OF SILICON IN RICE PLANT : I. A New Method for Determining the Localization of Silicon within Plant Tissues

While the essentiality of silicon to the growth of higher plants, in a strict sense, has remained questionable, beneficial effects of the element on the growth of rice plant have been repeatedly confirmed by Japanese workers1),2),3),4) to date. Recently, Japanese soil scientists have focused their efforts on the improvement of Akiochi, a well-known physiological disease of paddy rice, and have found that the application of silicate slags is one of the most effective practices. Systematic studies conducted by OTA et al. 5) OBATA) and revealed that silicon is the main factor responsible, for the beneficial effects of silicate slags on the improvement of Akiochi.

Studies on rice seed protease: VI. Metal Ion Activation of Rice Seed Peptidase*

Abstract Peptidase in rice seed was investigated with regard to metal ion activation. The embryo contained the highest activity of the peptidase which hydrolysed various synthetic peptldes (l-Leu-Gly-Gly, l-Leu-Gly, Gly-Gly, Gly-l-Leu, Gly-l-Phe, GlY-l-Met, etc.). The enzyme showed an optimum pH of 7.6 for the hydrolysis of Gly-Gly. The hydrolysis of the peptides by the peptidase was activated by metal ions (Mn2+, Co 2+) and inhibited by EDTA, except for the liberation of l-Len from l-Leu-Gly-Gly where Mn2+ was inactive and Co2+ was inhibitory. The metal ion effect was shown to involve activation of the enzyme rather than that of the substrate. The enzyme was activated by the activators for thlol groups and was sensitive to inhibition by the thiol reagents. It appeared probable that Mn2+ or Co2+ was bound through a thlol group at the active site of the enzyme.

Protein metabolism in rice seedling: I. Effect of the inhibitors of protein synthesis on the degradation of seed protein during germination*

Abstract The relationship between protein synthesis and degradation in germinating rice seed were studied with protein synthetic inhibitors. Both DNP and 8-AG inhibited the degradation of glutelin, the major storage protein in rice seed, while the inhibitors had no direct effect in the activity of rice seed proteinllse in vitro. The prevention can be partly ascribed to the Inhibition of proteinase synthesis because the inhibitors depressed the increase in proteinase activity during germination. When DNP treatment was started at the onset of germination, the degradation of glutelin in the endosperm was seriously inhibited and the endosperm remained rigid over 9 days of incubation at 30°C. In contrast, the inhibition was less efficient clent when the treatment was started in the later stage. It is suggested that the degradation of the storage protein in rice seed depends on the synthetic process of the hydrolytic enzymes which increase during germination. disintegrate the compartmentation of the endosperm a...

INVESTIGATIONS ON THE WATER ECONOMY OF VOLCANIC ASH SOILS

Abstract To elucidate the influence of climate and vegetation upon the vertical distribution of soil moisture and its seasonal change is one of the fundamental problems in the studies on water economy of volcanic ash soils, that cover the larger parts of Japan, and have characteristic soil-water system.1) Few data are now available in this field, despite the fact that management of volcanic ash soils is practically one of the most urgent problems in Japan.