McDowell J M, An Y Q, Huang S, McKinney E C, Meagher R B
Department of Biology, University of North Carolina, Chapel Hill 27599, USA.
Plant Physiol. 1996 Jul;111(3):699-711. doi: 10.1104/pp.111.3.699.
ACT7 encodes one of the six distinct and ancient subclasses of actin protein in the complex Arabidopsis actin gene family. We determined the sequence and structure of the Arabidopsis thaliana ACT7 actin gene and investigated its tissue-specific expression and regulation. The ACT7 mRNA levels varied by 128-fold among several different tissues and organs. The highest levels of aCT7 mRNA were found in rapidly expanding vegetative organs, the lowest in pollen. A translational fusion with the 5' end of ACT 7 (1.9 kb) joined to the beta-glucuronidase reporter gene was strongly and preferentially expressed in all young, developing vegetative tissues of transgenic Arabidopsis plants. ACT7 was the only Arabidopsis actin gene strongly expressed in the hypocotyl and seed coat. Although no beta-glucuronidase expression was seen in developing ovules or immature seeds, strong expression was seen in dry seeds and immediately after imbibition in the entire seedling. ACT7 was the only Arabidopsis actin gene to respond strongly to auxin, other hormone treatments, light regime, and wounding, and may be the primary actin gene responding to external stimuli. The ACT7 promoter sequence contains a remarkable number of motifs with sequence similarity to putative phytohormone response elements.
ACT7在复杂的拟南芥肌动蛋白基因家族中编码六种不同的古老肌动蛋白亚类之一。我们确定了拟南芥ACT7肌动蛋白基因的序列和结构，并研究了其组织特异性表达和调控。ACT7 mRNA水平在几种不同的组织和器官中变化了128倍。在快速生长的营养器官中发现aCT7 mRNA水平最高，在花粉中最低。与ACT 7（1.9 kb）5'端连接到β-葡萄糖醛酸酶报告基因的翻译融合体在转基因拟南芥植物的所有年轻、发育中的营养组织中强烈且优先表达。ACT7是拟南芥中唯一在胚轴和种皮中强烈表达的肌动蛋白基因。虽然在发育中的胚珠或未成熟种子中未观察到β-葡萄糖醛酸酶表达，但在干种子和吸水后立即在整个幼苗中观察到强烈表达。ACT7是拟南芥中唯一对生长素、其他激素处理、光照条件和伤口有强烈反应的肌动蛋白基因，可能是对外部刺激做出反应的主要肌动蛋白基因。ACT7启动子序列包含大量与假定的植物激素反应元件具有序列相似性的基序。
