Ethylene in senescence and stress
H. Hyodo; Y. Imai; Y. Yamazumi and F. Nishikawa
Proceedings of the APEC symposium on postharvest handling systems Bangkok, Thailand September 1-3, 2003. p. 99
2003
บทคัดย่อ
Ethylene in senescence and stress
Ethylene is involved in senescence of postharvest horticultural crops. Japanese morning glory (Pharbitis nil Choisy) flower senesced rapidly after harvest. The corolla started wilting shortly after harvest, which reached a stage of full closing within 24 h. The rise in ethylene production at an early stage was assumed to be responsible for initiating corolla wilting. Flower senescence was greatly suppressed by 2,5-norbornadiene (NBD), an inhibitor of ethylene action, which implies that ethylene is involved in senescence of Japanese morning glory. Broccoli (Brassica oleracea L. var. italica) florets senesced at a rapid rate after harvest at ambient temperatures. The increase in ethylene production in florets correlated with the rise in ACC oxidase activity. The levels of gene transcripts of ACC oxidase increased in florets after harvest in accordance with the rise in the enzyme activity. Senescence of broccoli florets was strongly retarded by NBD, which suggests that ethylene regulates the rate of senescence of broccoli florets. Various forms of stresses are involved in induction of ethylene production, which include wounding and disease as abiotic or biotic stress. Winter squash (Cucurbita maxima Duch.) fruit produced in the mesocarp tissue upon wounding. ACC synthase activity and its gene expression were induced coordinately in response to wounding. A large amount of ethylene was produced in sweet potato (Ipomoea batatas Lam.) root tissue infected by black rot fungus (Ceratocystis fimbriata Ell. & Halst). Ethylene production in the root (host) tissue was induced in response to fungal invasion. Ethylene synthesis occurred via a pathway independent of the methionine-ACC pathway, in which linolenic acid may serve as a substrate in the presence of cupric ion. During postharvest handling and storage of horticultural crops, various kinds of stresses induce ethylene synthesis, leading to acceleration of senescence.