Takafumi Tezuka

Proteomic analysis of cucumber seedling roots subjected to salt stress.

To understand metabolic modifications in plants under salt stress, the physiological and biochemical responses of cucumber (Cucumis sativus L. cv. Jinchun No. 2) seedlings to salt stress was investigated. The dry weight and fresh weight of cucumber seedling roots were significantly reduced by treatment with NaCl; Na(+) and Cl(-) were increased, while K(+) and K(+)/Na(+) ratio were decreased. To identify components of salt stress signaling, we compared the high resolution two-dimensional gel electrophoresis (2-DE) protein profiles of control and NaCl-treated roots, and the intensity of 34 protein spots varied. Of these spots, the identities of 29 (21 up-regulated and 8 down-regulated protein spots induced after salt stress) were determined by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and liquid chromatography electro-spray ionization tandem mass spectrometry (LC-ESI-MS/MS). The majority of the proteins had functions related to metabolism, energy and transport, and are involved in regulating reactions and defending against stress. A semi-quantitative reverse transcriptional-polymerase chain reaction (PCR) approach based on peptide sequences was used to compare transcript and protein accumulation patterns for 10 candidate proteins. Of these proteins, 8 patterns of induced transcript accumulation were consistent with those of induced protein accumulation. It is therefore likely that the response of the plants proteome to NaCl stress is complex, and that the identified proteins may play an important role in regulating adaptation activities following exposure to NaCl stress in order to facilitate ion homeostasis.

Physiological activation in radish plants by UV-A radiation

Abstract Effects of near-UV, especially UV-A, irradiation from UV lamps on the growth and physiological activity of radish plants were investigated by growing plants in plastic frames covered with a poly(vinyl chloride) film that was opaque to solar UV radiation on the Earths surface. The growth of radish plants was promoted by the UV-A radiation, and the promotion by UV-A radiation was associated with an increase in chlorophyll content and photosynthetic activities. Furthermore, nitrate reductase activities, levels of soluble protein, levels of vitamin C (ascorbic acid + dehydroascorbic acid) and levels of nicotinamide coenzymes (NAD(H) and NADP(H)) in leaves and in the so-called globe “root”, which includes stem tissue in radish plants, were also elevated by UV-A radiation. Taken together, these data suggest that promotion of plant growth by UV-A radiation involves the promotion of carbon and nitrogen metabolism in radish plants.

Growth promotion of tomato and radish plants by solar UV radiation reaching the Earth's surface

Abstract The effect of natural solar UV radiation on the growth of tomato and radish plants was studied using polyvinylchloride films with different UV transmissions. The growth (fresh and dry weights) of tomato plants exposed to UVA (400-320 nm) radiation (UVC-320 film, transmission above 320 nm) was greater than that of plants exposed to no UV radiation (UVC-400 film, transmission above 400 nm) or to mainly near-UV radiation (400-300 nm; including UVA (400-320 nm) and the longer wavelength region within the UVB (320-280 nm); UVC-290 film, transmission above 290 nm). Furthermore, the growth promotion of tomato and radish plants on exposure to UVA has associated with an increase in chlorophyll content and photosynthetic activity. Dark respiration of tomato and radish plants was also promoted by radiation (near-UV and UVA region) through UVC-290 and UVC-320 films. Radiation with UVA delayed the senescence of tomato leaves.

Methane flux and regulatory variables in soils of three equal-aged Japanese cypress (Chamaecyparis obtusa) forests in central Japan

To compare factors that control methane flux in forest soils, we studied three equal-aged Japanese cypress (Chamaecyparis obtusa) forests in Chubu district, central Japan. The three sites are located at different altitudes: 630 m (SET), 1010 m (INB), and 1350 m (OSK). Methane was absorbed at every site. The highest uptake rate was observed in the middle-altitude soil (INB, 5.89 mg CH4 m−2 d−1), which was the only site where methane uptake rate was correlated with air and soil surface temperatures. Methane flux in the field was not correlated with water content, inorganic N content, or water-soluble organic carbon. C/N ratio was correlated with methane flux (r=0.64,p<0.001). The results suggest that some organic inhibitors might be produced through decomposition of organic matter. There was a negative correlation between methane uptake rate and water-soluble Al (r=−0.63,p<0.001). Inhibition of methane consumption by 1 and 5 mM Al solutions was observed in laboratory incubation. This result suggests that water-soluble Al may be a factor controlling methane uptake. Multiple regression with a backward-elimination procedure identified three variables that were significantly associated with methane flux in the field (p<0.05): air temperature, C/N ratio, and the concentration of water-soluble Al.

Structure, molecular evolution, and gene expression of primate superoxide dismutases.

Mn- and Cu,Zn-superoxide dismutase (SOD) cDNAs of eight primate species, Pan troglodytes, Pongo pygmaeus, Hylobates lar, Macaca fuscata, Macaca fascicularis, Macaca mulatta, Cebus apella, and Callithrix jacchus, were cloned. The whole protein-coding sequences were covered, comparing 198 and 153 (or 154) amino acids, for Mn- and Cu,Zn-SODs, respectively. Residues forming metal ligands were completely conserved in the two primate SODs and nucleotide/amino acid substitutions were more frequent in Cu,Zn-SODs than in Mn-SODs. Molecular evolutionary analyses showed Mn-SOD to have evolved at a constant rate and its phylogenetic tree well reflected primate phylogeny. Cu,Zn-SOD was shown to have evolved differently between primate lineages. The significant high ratio of a non-synonymous/synonymous rate was found in the lineage leading to great apes and humans, showing that this lineage underwent positive Darwinian selection. Southern hybridization suggested that the genes for primate Mn- and Cu,Zn-SOD exist as single copies. Northern analysis in various Japanese monkey tissues showed Mn- and Cu,Zn-SOD expression to be high in the liver, kidneys, and adrenal glands.

Proteomic study participating the enhancement of growth and salt tolerance of bottle gourd rootstock-grafted watermelon seedlings.

An insertion grafting technique to do research on salt tolerance was applied using watermelon (Citrullus lanatus [Thunb.] Mansf. cv. Xiuli) as a scion and bottle gourd (Lagenaria siceraria Standl. cv. Chaofeng Kangshengwang) as a rootstock. Rootstock-grafting significantly relieved the inhibition of growth and photosynthesis induced by salt stress in watermelon plants. Proteomic analysis revealed 40 different expressed proteins in response to rootstock-grafting and/or salt stress. These proteins were involved in Calvin cycle, amino acids biosynthesis, carbohydrate and energy metabolism, ROS defense, hormonal biosynthesis and signal transduction. Most of these proteins were up-regulated by rootstock-grafting and/or susceptible to salt stress. The enhancement of the metabolic activities of Calvin cycle, biosynthesis of amino acids, carotenoids and peroxisomes, glycolytic pathway and tricarboxylic acid cycle will probably contribute to intensify the biomass and photosynthetic capacity in rootstock-grafted seedlings under condition without salt. The accumulation of key enzymes included in these biological processes described above seems to play an important role in the enhancement of salt tolerance of rootstock-grafted seedlings. Furthermore, leucine-rich repeat transmembrane protein kinase and phospholipase may be involved in transmitting the internal and external stimuli induced by grafting and/or salt stress.

Regulation of the growth and photosynthesis of cherry tomato seedlings by different light irradiations of light emitting diodes (LED)

The growth and photosynthetic characteristics of cherry tomato seedlings were investigated under seven light irradiations such as dysprosium lamps (white light; control, C), red light emitting diodes (LEDs) (R), blue LEDs (B), orange LEDs (O), green LEDs (G), red and blue LEDs (RB) and red, blue and green LEDs (RBG) with the same photosynthetic photon flux density (about 320 μmol m-2 s-1) for 30 days. Morphological appearances of seedlings were significantly different between light treatments, that is, the plants under RB and RBG were shorter and stronger than those under C, while those under O, G and R were higher and weaker. The higher carbohydrate contents were in plants containing blue treatment, B, RB and RBG. Photosynthetic pigments were shown to have significant difference under respective light irradiations of LEDs. The higher photosynthetic pigments were in leaves of seedlings containing blue light treatment, RBG, RB, B, C and G treatments, the lower the pigments were in those with R and O treatments. Net photosynthesis (Pn) was the highest in leaves of seedlings with RB and RBG and the lowest in those with G. Compared with C treatment, light compensation point and light saturation point of seedlings with R, RB and RBG increased, but those with O and G decreased. Electron transport rate (ETR), quantum efficiency of photosystem II photochemistry (ΦPSII), photochemical quenching (qP) and efficiency of excitation energy capture by open PSII reaction centres (Fv′/Fm′) in seedlings with B, RB and RBG treatments were significantly greater than those of the other treatments. Taken together, RB and RBG of LEDs were shown to be beneficial factors for the growth and photosynthesis in cherry tomato seedlings. Key words : Light-emitting diode (LED), light quality, cherry tomato, growth, photosynthetic characteristics.

Effects of proline on photosynthesis, root reactive oxygen species (ROS) metabolism in two melon cultivars ( Cucumis melo L.) under NaCl stress

Effects of 0.2 mM proline applied to saline nutrient solution on biomass, chlorophyll content, photosynthetic parameters, reactive oxygen species and antioxidant enzymes activities of two melon cultivars (cv. Yuhuang and cv. Xuemei) were examined. Results indicate that exogenous proline increased the fresh and dry weights of both melon cultivars under NaCl stress, raised their chlorophyll content, net photosynthetic rate (Pn), actual efficiency of photosystem II (ΦPSII), enhanced the activity of SOD, POD, CAT, APX, DHAR and GR in their roots, lowered the superoxide anion radical level and reduced the hydrogen peroxide (H 2 O 2 ) content and malondialdehyde (MDA) content. Exogenous proline also alleviate salinity-induced damage of membrane in both melon cultivars. In conclusion, proline treatment enhanced the salinity tolerance of both melon plants and alleviated their salinity-induced damage. However, all the above effects of proline were markedly more significant in cv. Xuemei than in cv. Yuhuang, suggesting that proline had different effects on different cultivars of melon plants. Key words : Proline, photosynthesis, reactive oxygen species, antioxidant enzymes, salt tolerance, NaCl stress.

ACTIVATION OF GROWTH AND NODULATION IN A SYMBIOTIC SYSTEM BETWEEN PEA PLANTS AND LEGUMINOUS BACTERIA BY NEAR-UV RADIATION

Abstract The effects of near-UV (300–400 nm) radiation on shoot length, fresh weight, photosynthesis, respiration, nodulation (nodule formation), N2-fixation (nitrogenase activity) and flavonoid level have been examined in the symbiotic combination between pea plants (Pisum sativum L. cv. Sparkle) and leguminous bacteria (Rhizobium leguminosarum bv. Viciae strain 128c53). The growth (shoot length and fresh weight) of pea plants is enhanced by near-UV radiation. The net photosynthesis and dark respiration are also significantly promoted. The nodulation and symbiotic N2-fixation are enhanced about two and eight times, respectively, by near-UV radiation. The content of flavonoids in pea roots, which may promote nodulation, is increased 46% by near-UV radiation. A possible mechanism for the action of near-UV radiation on the symbiotic system between leguminous plants and leguminous bacteria is discussed.

Bottle gourd rootstock-grafting affects nitrogen metabolism in NaCl-stressed watermelon leaves and enhances short-term salt tolerance

The plant growth, nitrogen absorption, and assimilation in watermelon (Citrullus lanatus [Thunb.] Mansf.) were investigated in self-grafted and grafted seedlings using the salt-tolerant bottle gourd rootstock Chaofeng Kangshengwang (Lagenaria siceraria Standl.) exposed to 100mM NaCl for 3d. The biomass and NO3(-) uptake rate were significantly increased by rootstock while these values were remarkably decreased by salt stress. However, compared with self-grafted plants, rootstock-grafted plants showed higher salt tolerance with higher biomass and NO3(-) uptake rate under salt stress. Salinity induced strong accumulation of nitrate, ammonium and protein contents and a significant decrease of nitrogen content and the activities of nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS), and glutamate synthase (GOGAT) in leaves of self-grafted seedlings. In contrast, salt stress caused a remarkable decrease in nitrate content and the activities of GS and GOGAT, and a significant increase of ammonium, protein, and nitrogen contents and NR activity, in leaves of rootstock-grafted seedlings. Compared with that of self-grafted seedlings, the ammonium content in leaves of rootstock-grafted seedlings was much lower under salt stress. Glutamate dehydrogenase (GDH) activity was notably enhanced in leaves of rootstock-grafted seedlings, whereas it was significantly inhibited in leaves of self-grafted seedlings, under salinity stress. Three GDH isozymes were isolated by native gel electrophoresis and their expressions were greatly enhanced in leaves of rootstock-grafted seedlings than those of self-grafted seedlings under both normal and salt-stress conditions. These results indicated that the salt tolerance of rootstock-grafted seedlings might (be enhanced) owing to the higher nitrogen absorption and the higher activities of enzymes for nitrogen assimilation induced by the rootstock. Furthermore, the detoxification of ammonium by GDH when the GS/GOGAT pathway was inhibited under salt stress might play an important role in the release of salt stress in rootstock-grafted seedlings.