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Mayuko Otsubo and Mari Iwaya-Inoue

Florets of cut gladiolus (Gladiolus ×grandiflora hort. cv. Fujinoyuki) spikes kept at 25 °C under 14 h light/10 h dark condition showed severe wilting 4 days after flower opening. Treatment with 0.1 m trehalose prolonged vase-life 2 days, whereas inhibitors and other sugars had no effect. The upper florets also opened properly in trehalose-treated spikes, but not in cycloheximide-treated ones. After 4 days, the first florets of trehalose-treated spikes maintained water content more effectively than did controls or spikes treated with other sugars. The parenchyma adjacent to vascular bundles in the petals of trehalose-treated spikes maintained viability for 4 days. These results suggest that trehalose preserves cell viability in gladiolus spikes, thereby enhancing water uptake into petal tissues.

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Mari Iwaya-Inoue and Mutsumi Takata

The tepals of cut tulips (Tulipa gesneriana L. cv. Ile de France) kept at 20 °C had severely wilted 7 days after flower opening. Suppression of abscission and undesirable growth of tepals is required to extend vase life. Treatment with 50 mm trehalose in combination with 50 μm chloramphenicol (CAP) delayed abscission by 4 days compared with stems placed in distilled water or CAP without trehalose. Only 4% of trehalose+CAP-treated flowers exhibited tepal abscission 7 days after harvest, while 82% and 60% of flowers held in distilled water and CAP, respectively, did so; the tepals of trehalose+CAP-treated flower stems contained 50% more water than did those treated with CAP alone. Further, trehalose did not promote elongation of epidermal parenchyma cells in tepal tissues, but maintained radial enlargement of the cells. Thus, trehalose+CAP treatment is effective in prolonging vase life without abscission, water loss, or elongation of cells in tulip tepals, but slight wilting occurs in leaves.

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Mayuko Otsubo and Mari Iwaya-Inoue

Florets of cut gladiolus (Gladiolus ×grandiflora hort. cv. Fujinoyuki) spikes kept at 25 °C under 14 h light/10 h dark condition showed severe wilting 4 days after flower opening. Treatment with 0.1 m trehalose prolonged vase-life 2 days, whereas inhibitors and other sugars had no effect. The upper florets also opened properly in trehalose-treated spikes, but not in cycloheximide-treated ones. After 4 days, the first florets of trehalose-treated spikes maintained water content more effectively than did controls or spikes treated with other sugars. The parenchyma adjacent to vascular bundles in the petals of trehalose-treated spikes maintained viability for 4 days. These results suggest that trehalose preserves cell viability in gladiolus spikes, thereby enhancing water uptake into petal tissues.

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Hiroshi Wada, Mari Iwaya-Inoue, Mitsuru Akita, and Hiroshi Nonami

Two cultivars of tulip (Tulipa gesneriana L.) were used to check the effect of trehalose-feeding on longevity of vase life. `Oxford' plants were grown from bulbs, and trehalose-fed cut flowers were compared with the intact plants grown in pots. `Pink Diamond' flowers were obtained commercially as cut flowers from the market, and trehalose-feeding was examined by using only flower parts. In both cultivars of plants, it was confirmed that trehalose-feeding enhanced longevity of the vase life significantly at room temperature. Additionally, mechanisms of prolonging the vase life with trehalose-fed flowers were studied by comparing the water status in the zone of elongation of tulip tepals when their growth rates were modified with different treatments. In the elongating region of tulip tepals, cell elongation rates were linearly correlated to sizes of the growth-induced water potential regardless of treatments. It was found that trehalose-feeding reduced the hydraulic conductance, resulting in a decrease in cell elongation rates. Also, trehalose helped to maintain turgor of tepal cells for longer periods. Furthermore, trehalose enhanced pigmentation in tepals, and thus, trehalose is believed to have had a role in altering the metabolism in elongating cells and in reducing hydraulic conductivity in membranes.