The ACC Synthase Gene

ACC合成酶是植物乙烯生物合成途径的关键调控酶，目前各种植物激素和环境刺激诱导ACC合成酶的机制尚不清楚。最近在Theologis博士的实验室中获得的与西葫芦ACC合成酶mRNA互补的DNA序列的实验证据表明，酶诱导剂，如IAA，损伤Li离子在转录或转录后水平起作用。通过对西葫芦和番茄中ACC合成酶基因的结构和调控进行研究，深入了解其在各种激素和胁迫条件下表达的生化机制及其在植物衰老中的调控作用。这项建议的具体目标是：1)从西葫芦和番茄中分离出ACC合成酶mRNA的互补序列和基因组序列并进行结构表征；2)生长过程中ACC合成酶基因表达的发育调控；3)确定参与乙烯和生长素调控ACC合成酶基因表达的顺式DNA调控元件。4) ACC合成酶基因在体内和离体细胞核中对各种激素和环境胁迫条件的表达调控；5)ACC合成酶反义构建体对乙烯诱导果实成熟和厌氧诱导的增殖的抑制作用。乙烯是具有生物活性的最简单的有机分子之一。它被认为是已知的调节植物生长，发育和衰老的许多方面的果实成熟激素。ACC合酶是乙烯合成途径中的关键酶。

The mechanism of induction of ACC synthase, the key regulatory enzyme in the ethylene biosynthetic pathway in plants, by various plant hormones and environmental stimuli is poorly understood. Recent experimental evidence obtained in Dr. Theologis' lab with DNA sequences complementary to the ACC synthase mRNA from zucchini indicate that enzyme inducers such as IAA, wounding Li ions act at the transcriptional or posttranscriptional level. Studies on the structure and regulation of ACC synthase gene(s) in zucchini and tomato are proposed to gain insight into the details of the biochemical mechanism that regulates their expression by various hormones and stress conditions as well as on their role in regulating plant senescence. The specific aims of this proposal are: 1) Isolation and structural characterization of complementary and genomic sequences to ACC synthase mRNA from zucchini and tomato, 2) Developmental regulation of ACC synthase gene expression during growth, 3) Determination of this cis acting DNA regulatory elements that are involved in ethylene and auxin regulated ACC synthase gene expression, 4) Regulation of expression of ACC synthase gene(s) in vivo and in isolated nuclei in response to various hormones and environmental stress conditions, 5) Inhibition of ethylene induced fruit ripening and anaerobiosis-induced epinasty with ACC synthase antisense constructs. %%% Ethylene is one of the simplest organic molecules with biological activity. It is considered to be the fruit ripening hormone known to regulate many aspects of plant growth, development and senescence. ACC synthase is the key enzyme in the synthetic pathway of ethylene.