The mechanism of ethylene biosynthesis and its role in horticultural crops and regulation and function of ethylene synthesis during ripening and senescence

乙烯生物合成机制及其在园艺作物中的作用及乙烯合成在成熟和衰老过程中的调控和功能

基本信息

批准号：
13660027
负责人：
HYODO Hiroshi
金额：
$ 2.24万
依托单位：
Shizuoka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

项目摘要

Ethylene plays an essential role in growth, development ; differentiation, and senescence of plants. In horticultural crops ethylene is closely involved in the mechanism of ripening and senescence. On the other hand, ethylene is rapidly produced in response to various kinds of stresses such as wounding and disease caused by infection with microorganisms. (1)Ethylene biosynthesis and its regulation during senescence of broccoli florets (flower buds): Broccoli is harvested while florets are still green and immature which are covered with green sepals. After harvest senescence proceeds rapidly in florets at ambient temperatures in which yellowing progresses due to chlorophyll degradation. The high levels of ascorbic acid (vitamin C) rapidly decline after harvest during senescence. The rate of ethylene production increased during senescence which was paralleled by the increase in ACC oxidase activity and its gene expression. The rate of ethylene biosynthesis in broccoli florets was regulat … More ed by the gene expression of ACC synthase and ACC oxidase after harvest. Harvesting broccoli causes the cessation of the transport of water, hormones, sugars, amino acids, and minerals from the mother plant and together with wounding by cutting the stem may result in triggering or accelerating senescence of the young flower organ of florets. (2)Ethylene biosynthesis and its mechanism in sweet potato root tissue infected by black rot fungus (Ceratocystis fimbriata): A large amount of ethylene is produced in sweet potato roots upon infection by black rot fungus. The pathway of ethylene biosynthesis was independent on methionine-ACC pathway that is widely operating in higher plants. We have found the new pathway for the synthesis of ethylene in sweet potato root tissue infected by the pathogen. The mechanism of the novel pathway is summarized as follows. In response to infection with the fungus, phospholipase A_2 is activated, liberating linolenic acid, which is hydroperoxidized by lipoxygeriase in the host tissue. Then, ethylradical is cleaved from the peroxidized linolenic acid, which is oxidized by cupric ion to yield ethylene. Ethylene produced may be involved in the activation of metabolism in sweet potato root tissue infected by the pathogen. Less

乙烯在植物的生长、发育、分化和衰老中起着重要作用，乙烯与植物的成熟和衰老机制密切相关。微生物感染引起的伤病。 (1)西兰花小花(花蕾)衰老过程中乙烯的生物合成及其调控：西兰花在采收时。收获后，小花仍呈绿色且未成熟，在环境温度下，小花迅速衰老，由于叶绿素降解，高水平的抗坏血酸（维生素 C）在衰老过程中迅速下降。衰老期间乙烯产量增加，与 ACC 氧化酶活性及其基因表达的增加同时发生。收获后，小花受到 ACC 合酶和 ACC 氧化酶基因表达的调节。收获西兰花会导致母株停止运输水、激素、糖、氨基酸和矿物质，并会因切割西兰花而造成伤害。茎可能引发或加速小花幼花器官的衰老(2)黑穗病甘薯根组织乙烯生物合成及其机制。腐菌（Ceratocystis fimbriata）：甘薯根部被黑腐菌感染后会产生大量乙烯。乙烯生物合成途径独立于在高等植物中广泛运行的蛋氨酸-ACC途径。受病原体感染的甘薯根组织中乙烯的合成途径该新途径的机制总结如下：响应真菌感染，磷脂酶A_2被激活，释放亚麻酸，亚麻酸在宿主组织中被脂氧酶氧化，然后，乙基自由基从过氧化亚麻酸中裂解，被铜离子氧化产生乙烯，可能参与甘薯根组织代谢的激活。较少被病原体感染。