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In order to diagnose the nutritional disorders caused by various environmental stress, biochemical test, xylem sap analysis and colorimetric petiole analysis were used to assay symptoms well before the severe development. Among the various enzymatic analysis, alkaline phosphatase activity was highly specific to calcium deficiency while in vivo nitrate reductase activity was not stable parameter in response to nitrogen deficiency. Determination of nitrogen, phosphorus and magnesium by colorimetric petiole analysis was sensitive to induced deficiencies. The status of potassium in the plant, however, could be better determined with the xylem sap analysis. Salinity stress induced by low osmotic potential of the nutrient solution increased the activity of alkaline phosphatase, showing similar results as calcium deficiency. Magnesium and phosphorous contents by the colorimetric petiole analysis were particularly low when the roots in anoxia.
Soybean sprouts are one of the most-favored traditional vegetables around the world. The sprouts are usually consumed 7 to 10 days after sowing depending upon the growing conditions. High-quality sprouts should have less secondary roots, short and well-swollen hypocotyls in pure white color, and small cotyledons in hooked position. Cytokinins were reported to be effective in producing such sprouts by promoting sprout growth while inhibiting the excessive hypocotyl elongation and secondary root growth. Seeds of four soybean cultivars with different characteristics were soaked in water for 4 h and, 2 to 3 h after the imbibition, the seeds were soaked again in solutions of different cytokinins such as benzyladenine (BA), BA-riboside (BAR), BPA, 2iP, 2iP-riboside, 4-CPPU, and kinetin-riboside (KR) for 10 min. After the treatment, the sprouts were grown in a plastic tube (25 cm height × 10.5 cm diameter) a dark culture room with ample watering every 4 h. After 7 days of growth, uniform samples were taken from each treatment and the sprout characteristics were examined. Some cytokinins such as BA, BAR, 4-CPPU were highly effective in promoting the sprout growth (fresh weight) even though the hypocotyl length was markedly reduced. Other cytokinins such as 2iP, 2iPR, and KR had no effect on sprout growth. Hypocotyl diameter was markedly increased by BA and 4-CPPU treatment, thus resulting in short, strong and good quality sprouts. Cultivars responded differently to cytokinin treatment by showing different growth promotion depending upon the sprout parts. Injury-like symptoms, abnormal and twisted heads or cotyledons, appeared in cytokinin-treated sprouts at high concentrations and the symptoms were severe when the sprouts were grown at high temperatures. In all the cultivars tested, BAR appeared to be better than others in terms of sprout quality and growth promoting characteristics.
Twenty-two kilodalton potato proteinase inhibitor (22-kD PPI) is synthesized as a pre-protein with a hydrophobic signal sequence of 40 amino acids. Using immunogoldcytochemistry we determined the subcellular localization of the 22-kD PPI. Using 22-kD PPI specific antibodies and GAR-IgG colloidal gold for electron-microscopical immunocytochemistry, the 22-kD PPI was found to be localized mainly in the vacuole and cytoplasm of both tubers and wounded leaves of potatoes (Solanum tuberosum L). Within the vacuole, label was found predominantly over the protein aggregates and protein cluster-like structure. Neither cell wall nor the intercellular space contained detectable levels of the 22-kD PPI. We found one basic residue with a hydrophobic core followed by a cleavage site for signal peptidase in the deduced amino acid sequence of the 22-kD PPI cDNA clone, p34021. A conserved glutamine, which is thought to be required for correct sorting in all vacuolar proteins sequenced to date, was also found in amino acid sequence derived from the 22-kD PPI cDNA clone, p34021.
To determine whether chilling tolerance is related to cold acclimation, changes in physiological responses and activity of antioxidative enzymes were investigated in leaves of cucumber (Cucumis sativus L.) grown in controlled environments. Plants were exposed to 15 °C (cold-acclimated) or 25 °C (nonacclimated) for 3 days, under 50 μmol·m-2·s-1 photosynthetic photon flux and 70% relative humidity. Plants were then exposed to 8 °C chilling temperature for 3 days, and allowed to recover in a growth chamber at 25 °C for 3 days. Measurements of leaf water content, cellular leakage, lipid peroxidation, chlorophyll a fluorescence, and quantum yield showed that cold-acclimated leaves were less affected by chilling compared to nonacclimated leaves. Cold-acclimated leaves recovered faster than nonacclimated leaves with regard to all variables examined. Catalase and ascorbate peroxidase activities were induced in cold-acclimated leaves, but not in nonacclimated leaves. These data indicate that cold acclimation increased chilling tolerance of cucumber in association with antioxidative enzymes.