Tetsuo Hara

Effect of temperature during ripening on grain quality of rice

Abstract Temperature during grain ripening has been shown to affect amylose content and gelatinization temperature of rice starch (1–6). These studies demonstrated that high ambient temperature results in lower amylose content and higher gelatinization temperature of the starch. Rice starches obtained from rice grains that matured at lower temperature had higher iodine blue values and were more susceptible to alkali digestion than those that ripened at higher temperature.

Comparison of the toxicity of heavy metals to cabbage growth

SummaryCabbage plants were grown for 55 days with a nutrient solution containing 1 and 10 ppm of V, Cr(III), Cr(VI), Mn, Fe, Co, Ni, Cu, Zn, Cd, Hg(I), orHg(II). A comparison of the plant growth and chemical analysis revealed that Cr(VI), Cu, Cd, and Hg(II) in the solution are most toxic to the plant growth (hence detrimental to the cabbage-head formation) and Mn, Fe, and Zn are less toxic than other heavy metals, and that Mn, Zn, Co, Ni, and Cd and translocated into all the plant organs while V, Cr(III), Cr(VI), Fe, Cu, Hg(I), and Hg(II) are accumulated in the roots.

GROWTH RESPONSE OF CABBAGE PLANTS TO TRANSITION ELEMENTS UNDER WATER CULTURE CONDITIONS : I. Titanium, Vanadium, Chromium, Manganese, and Iron

Abstract Cabbage plants were water-cultured under 4 levels of titanium (0,0,4,4,20 ppm), vanadium (0, 0.4,4, 20 ppm), chromium (0, 0.2, 2, 10 ppm), manganese (0, 0.4, 4, 20 ppm), and iron (0, 1, 10, 50 ppm), and the effects of the elements supplied on the growth of the plants and on the distribution of the elements in the plants were studied. The dry weight of a whole plant and of inner leaves (yield) without the addition of Ti, V, and Cr did not decrease, while that without the addition of Mn and Fe decreased slightly. The addition of Ti, V, Cr, Mn, and Fe (more than 0.4, 0.4, 2, 4, and 10 ppm, respectively) decreased the yield. Slight transition element-induced chlorosis was observed in the plots at high levels of Ti, Cr, and Mn. The contents of the elements in the plants increased with an increase in the concentration of each element in the culture solution. The critical contents of Mn and Fe in plant-tops which resulted in a slight decrease in the yield due to the deficient injury were estimated to be...

In vitro bulblet regeneration from bulbscale explants of Lilium japonicum Thunb. Effect of plant growth regulators and culture environment

SummaryThe interaction of auxin (NAA), cytokinins (BA, kinetin, 2iP and zeatin) and culture environment (light and temperature) on bulblet production from bulbscale explants of Lilium japonicum Thunb. were investigated. A combination of NAA and 2iP, in general, gave a better response than combinations involving other cytokinins. An incubation temperature of 20°C and continuous illumination were better than growing at 25°C in the dark. Regenerated bulblets predominantly originated from the basal end of explants in the control medium and this polarity was reversed by supplementing the medium with NAA + BA or NAA + 2iP. The importance of an illuminated environment for leaf induc-tion in regenerated bulblets is discussed.

Aluminum-Induced Lipid Peroxidation and Lignin Deposition Are Associated with an Increase in H2O2 Generation in Wheat Seedlings

Wheat (Triticum aestivum cv. Kalyansona) seedlings were exposed to 0, 10, 50, and 100 μM Al in a 250 μM CaCl2 solution for 24 h at pH 4.5. Root elongation decreased gradually, while the Al content markedly increased with increasing supply of Al in the solution. The generation of H2O2 during Al stress was investigated biochemically and histochemically, as well as other events related to the decomposition of H2O2. After 24 h treatment, root elongation inhibition was detected at all the concentrations of Al. The level of lipid peroxidation at 10 μM Al after 24 h treatment was similar to that of the control, while a significant increase in lipid peroxidation was detected at 50 and 100 μM Al. H2O2 generation was higher at 50 and 100 μM Al than that at 10 μM Al. These results suggest that Al-inducible lipid peroxidation may require excessive yield of H2O2. Time course experiment with 10 μM Al indicated that there is a strongly positive correlation between root elongation inhibition and cellular H2O2 yield. There were no significant changes in the activities of catalase (CAT) and ascorbate peroxidase (APX) in roots at 10 μM Al after 24 h treatment. However, a significant decrease in the activities of CAT and APX and a large increase in the activities of oxalate oxidase (OXO), guaiacol peroxidase (GPX), and coniferyl alcohol peroxidase (CA-POX) as well as lignin deposition were observed at 100 μM Al. These results suggest the possible involvement of OXO in the production of a large amount of H2O2 under severe Al stress, whereas GPX and CA-POX may be involved in the degradation of H2O2, leading to lignin deposition.

FACTORS AFFECTING CADMIUM UPTAKE BY THE CORN PLANT

Abstract Corn plants, were water-cultured by varying pH and concentration of calcium, phosphorus, zinc, and iron in nutrient solution containing graded levels of cadmium. The results obtained were summarized as follows: 1) With an increase of the cadmium concentration, the cadmium content of plants increased and the total dry weight and grain yield decreased markedly in the absence of calcium. Under these conditions the addition of calcium or iron caused a decrease of the cadmium content, and an increase of the dry weight and grain yield. The pH and the addition of phosphorus or zinc had no notable effect on the cadmium uptake. 2) The relationship between dry weight and cadmium content indicated that the critical cadmium content, above which plants suffer from the cadmium toxicity, was about 20 ppm on a dry matter basis, independent of treatments. 3) Calcium or iron at an adequate concentration in nutrient solution are effective to depress cadmium uptake by corn plants.

Effects of boron deficiency and calcium supply on the calcium metabolism in tomato plant

SummaryTomato plants were grown in water-culture with a different supply of Ca (10, 100 ppm) and B (0, 0.2 ppm), and the effects of B deficiency on the translocation and subcellular distribution of Ca in tomato plants were studied by using45CaCl2 as a carrier of Ca. Boron deficiency slight increased the total Ca uptake by the plant and inhibited the Ca translocation to the upper leaves. The incorporation of45Ca into the cell wall in the upper leaves was increased by B deficiency at both Ca levels. As Ca supply decreased, the distribution of45Ca in the 1N NaCl fraction of the cell wall increased only at 0.2 ppm B. As B supply decreased, the distribution of45Ca in the 0.6N HCl fraction increased at both Ca levels.These results suggest that B deficiency inhibit the translocation of Ca, and induce the abnormal changes of the Ca metabolism in the cell wall.

Chemical and sensory analysis of saffron produced through tissue cultures of Crocus sativus

Stigma-like structures were produced in tissue cultures (TC stigmas) from the ovary explants of C. sativus on MS medium supplemented with NAA and BA. The size of these structures was 2 to 3 cm in length. At higher concentrations of both NAA (54 µM) and BA (44 µM) white tubular abnormal structures were observed from ovary explants in addition to the TC stigmas. Crocin and picrocrocin, responsible for colour and bitter taste respectively, were found to be 6 and 11 times lower in TC stigmas than in the natural stigmas. The saffron obtained from tissue cultures was subjected to sensory analysis and compared with the data obtained from chemical analysis. The sensory data indicated that the saffron pigments produced in tissue cultures were one tenth that of natural stigmas. Sensory profile test showed that the tissue culture saffron was low in floral, spicy and fatty characteristics as compared to saffron obtained from flowers. This is the first report on the sensory analysis of a spice produced in tissue cultures.

Effects of aluminum and boron supply on growth of seedlings among 15 cultivars of wheat (triticum aestivum L.) grown in Bangladesh

Abstract Aluminum toxicity and boron deficiency are the major factors that limit plant growth and development in acid soils and in B-deficient soils. Root growth inhibition is an early symptom of AI toxicity and B deficiency. Effects of AI and B supply and their interaction on the growth of wheat (Triticum aestivum L.) seedlings were investigated using hydroponics. Fifteen wheat cultivars commonly grown in Bangladesh were used and found to differ considerably in their tolerance to AI toxicity and B deficiency. The relative root length of all the wheat cultivars at 50 µM AI (pH 4.5) ranged from 27 to 71% relative to the control (0 µM AI). Among the cultivars, Inia66 and Kalyansona were found to be the most Al-tolerant and sensitive cultivars, respectively, based on the data of relative root length, malate exudation and AI content of roots. Malate was detected in all the cultivars in the presence of 100 µM AI (pH 4.3). Inia66 exuded a 6-fold larger amount of malate and the AI content of roots was 4 times lower than that in Kalyansona. The vigorous seedling growth was observed at 40 µM B among the series of B treatments. Considerable cultivar differences in response to 40 µM B were observed among the 15 cultivars. Kalyansona was considered to be the most sensitive and Kheri the most tolerant to B deficiency. The interaction effects of B ( 40 and 200 µM) and AI (50 µM) on seedling growth were also examined in Inia66 and Kalyansona. Root growth was inhibited in the presence of Al but B supply especially at 200 µM B in the Kalyansona cultivar caused a slight improvement.

Characterization of NADP-isocitrate dehydrogenase expression in a carrot mutant cell line with enhanced citrate excretion

Citrate in the cytosol is converted to isocitrate, by the action of aconitase, and then isocitrate is converted to 2-oxoglutarate by the action of NADP-specific isocitrate dehydrogenase (NADP-ICDH). This pathway is modified in a mutant carrot (Daucus carotaL.) cell line [designated as insoluble phosphate grower (IPG): Koyama et al., 1992 Plant Cell Physiol. 33, 173–177], which releases large amounts of the citrate and grows faster than the wild-type cells in Al-phosphate medium. In the current study, the activities of aconitase in mitochondria and in crude extracts were similar in the mutant cells and the wild-type cells, suggesting that the activity of the cytosolic aconitase was similar among the cell types. By contrast, the NADP-ICDH activity in the crude extracts of the mutant cells was almost half that of the wild-type cells. Western blot analysis revealed that the cytosolic NADP-ICDH was the most abundant isoenzyme in both cell types. However the NADP-ICDH amount was lower in the mutant cells than that in the wild-type cells. Transcripts level of DcICDH1, which appeared to be a unique isoform encoding the cytosolic enzyme in carrot, was lower in the mutant cells than that of the wild-type cells. Thus, we inferred that the lower transcript level of the cytosolic isoform caused the lower NADP-ICDH activities in the mutant cells, compared with the wild-type cells.