Auto-regulation of the promoter activities of Arabidopsis 1-aminocyclopropane-1-carboxylate synthase genes AtACS4, AtACS5, and AtACS7 in response to different plant hormones §
Auto-regulation of the promoter activities of Arabidopsis 1-aminocyclopropane-1-carboxylate synthase genes AtACS4, AtACS5, and AtACS7 in response to different plant hormones §
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DOI：
10.1016/j.plantsci.2008.01.002
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发表时间：
2008-07
期刊：
影响因子：
5.2
通讯作者：
Xuenu Tang;Li Chang;Shuang Wu;Pengli Li;Guiqin Liu;N. Wang
中科院分区：
文献类型：
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作者：
Xuenu Tang;Li Chang;Shuang Wu;Pengli Li;Guiqin Liu;N. Wang
1-氨基环丙烷-1-羧酸合酶（ACC合酶，ACS）（S-腺苷-L-甲硫氨酸甲硫腺苷-裂解酶; EC 4.4.1.14）是乙烯生物合成的关键酶，受到激素本身的正反馈或负反馈调节。我们在前面的研究中，利用启动子-GUS（β-葡萄糖醛酸酶）报告基因的方法，发现拟南芥ACC合成酶多基因家族中的AtACS 4、AtACS 5和AtACS 7基因对外源乙烯处理表现出不同的反应。在这里，我们报告他们的发展表达谱和激素反应野生型和etr 1 -1突变体之间的差异。结果表明，这三个ACS成员在2周龄的野生型光生幼苗中均表达活跃，但在etr 1 -1突变体中表现出不同的表达谱。etr 1 -1突变体在拟南芥整个生活史中AtACS 7：：GUS的表达均受到显著抑制，而AtACS 4：：GUS和AtACS 5：：GUS的表达无明显变化。利用荧光GUS活性测定法研究了7种主要植物激素和乙烯前体ACC对这3个ACS基因启动子活性的影响。结果表明，外源IAA、ACC、阿坝和JA处理能提高野生型背景中AtACS 4的启动子活性，而ACC、阿坝和JA处理对etr 1 -1背景中AtACS 4的启动子活性几乎没有影响。阻断乙烯信号也消除了IAA和ABA诱导的AtACS 5：：GUS表达。ACS 7启动子对8种激素中的6种（GA 3、ACC、阿坝、JA、SA和BR）有响应，其中，在etr 1 -1突变体中，GA 3、ACC、SA和BR的增强作用被消除。在此基础上，讨论了乙烯信号在AtACS 4、AtACS 5和AtACS 7对不同激素反应的调控中的作用。
1-Aminocyclopropane-1-carboxylate synthase (ACC synthase, ACS) (S-adenosyl-l-methionine methylthioadenosine-lyase; EC 4.4.1.14), the key enzyme for ethylene biosynthesis, is subjected to positive or negative feedback regulation by the hormone itself. We have previously described, aided by promoter-GUS (β-glucuronidase) reporter approach, that among members of the multigene family of Arabidopsis ACC synthase, AtACS4, AtACS5 and AtACS7 genes exhibit different responses to exogenous ethylene treatment. Here we report differences in their developmental expression profiles and hormone responses between wild type and etr1-1 mutants. It was found that these three ACS members were all actively expressed in 2-week-old wild type light-grown seedlings but exhibited different profiles in etr1-1 mutant. The expression of AtACS7::GUS during the entire life cycle of Arabidopsis was greatly suppressed in etr1-1 mutant while the expressions of AtACS4::GUS and AtACS5::GUS exhibited no significant changes. The effects of seven major plant hormones and ethylene precursor ACC on the promoter activities of these three ACS genes were studied by fluorometric GUS activity assay. It was found that exogenous treatment of IAA, ACC, ABA or JA increased the promoter activity of AtACS4 in the wild type background but the promotions by ACC, ABA and JA were almost absent in the etr1-1 background. Block of the ethylene signaling also abolished both the IAA- and the ABA-induced AtACS5::GUS expression. The ACS7 promoter was responsive to six members of the eight hormones (GA3, ACC, ABA, JA, SA and BR), among which, the increases by GA3, ACC, SA and BR were abolished in the etr1-1 mutant. Based on these results, the role of ethylene signaling in regulating responses of AtACS4, AtACS5 and AtACS7 to different hormones was discussed.