摘要
脱落酸(ABA)生物合成一般有两条途径:C15直接途径和C40间接途径, 前者经C15法呢焦磷酸(FPP)直接形成ABA;后者经由类胡萝卜素的氧化裂解间接形成ABA, 是高等植物ABA生物合成的主要途径。9-顺式环氧类胡萝卜素氧化裂解为黄质醛是植物ABA生物合成的关键步骤, 然后黄质醛被氧化形成一种酮, 该过程需NAD为辅因子, 酮再转变形成ABA-醛, ABA-醛氧化最终形成ABA。在该途径中,玉米黄质环氧化酶(ZEP)、9-顺式环氧类胡萝卜素双加氧酶(NCED)和醛氧化酶(AO)可能起重要作用。
Two pathways have been proposed for the biosynthesis of ABA: the ‘direct pathway’and ‘indirect pathway’. In the direct pathway, which operates in some fungi, ABA is derived fromfarnesyl diphosphate; in indirect pathway, ABA is produced from the oxidative cleavage of carotenoids.The first committed step for ABA biosynthesis in plants is the oxidative cleavage of a 9-cis-epoxycarotenoid(C40) to produce xanthoxin(C15) and a C25 by-product(Fig.2). Xanthoxin is then oxi-dized to a ketone by an NAD-requiring enzyme. Consequently, there is a nonenzymatic desaturationof the 2'-3' bond and opening of the epoxide ring to form abscisic aldehyde. In the final step of thepathway, abscisic aldehyde is oxidized to ABA. These endogenous enzymes such as zeaxanthinepoxidase(ZEP), 9-cis-epoxycarotenoid dioxygenase(NCED) and aldehyde oxidase(AO) may playkey roles in the regulation of ABA biosynthesis in higher plants.
出处
《植物学通报》
CSCD
北大核心
2004年第3期352-359,共8页
Chinese Bulletin of Botany
基金
This work was supported by the grants of the key project on scientific
technological researchfrom the Ministry of Education (03098)
the‘Thousand-hundred-ten project’cultivating excellent person-nel from the Department of Education of Guangdong pr
