ISHS Acta Horticulturae 394: Plant Bioregulators in Horticulture
REGULATION BY CO2 OF WOUND-INDUCED ACC SYNTHASE GENE EXPRESSION IN MESOCARP TISSUE OF WINTER SQUASH FRUIT |
| Authors: | Y. Kubo, Y. Yamashita, T. Ono, F.M. Mathooko, H. Imaseki, A. Inaba |
| Keywords: | ACC (1-aminocyclopropane-1-carboxylic acid) synthase, ACC oxidase, Ethylene, CO2-enriched atmosphere, Gene expression, Northern blot analysis, Cucurbita maxima |
| DOI: | 10.17660/ActaHortic.1995.394.23 |
| Abstract:
Effects of CO2 and diazocyclopentadiene (DACP), an inhibitor of ethylene action, on wound-induced ethylene biosynthesis were examined in winter squash (Cucurbita maxima Duch. cv Ebisu) fruit. Cubes (5 mm) prepared from the mesocarp tissue were incubated for 8h at 25°C under various concentrations of CO2 with or without DACP preteatment. Northern blot analysis was applied to the total RNA using labeled probes prepared by a multiprimer DNA labeling system and a-[32P]dCTP with a Hind III fragment from pCMW33 (Nakajima et al. 1990, wound-induced type of ACC synthase gene) as template. At all concentrations tested, CO2 suppressed wound-induced ethylene production, 1-aminocyclopropane-1-carboxylic acid (ACC) synthase and ACC oxidase activities and the expression of ACC synthase gene. The highest suppression of ACC synthase gene expression was observed in 5% CO2, ACC synthase activity in 5–40%, and ethylene production and an increase in ACC oxidase activity in 80%CO2. DACP stimulated wound-induced ACC synthase activity and gene expression but suppressed ACC oxidase activity. Our results suggest that wound-induced ACC synthase and ACC oxidase in winter squash are controlled by negative and positive feedback systems respectively and that CO2 suppresses wound-induced ethylene by transcriptional inhibition of ACC synthase gene and by inhibition of ACC oxidase activity. Possible mechanisms of ethylene biosynthesis affected by CO2 and DACP are discussed. | |
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