LE-ACS6启动子在LE-ACS6::GUS转基因拟南芥中的特异性

Promoter Specificity of LE-ACS6 Gene in LE-ACS6::GUS Transgenic Arabidopsis Plants

通过对不同发育时期LE-ACS6::GUS转基因拟南芥中GUS表达特异性的研究,证明LE-ACS6基因的启动子在拟南芥中也表现启动参与第一系统乙烯合成的关键酶基因的活性。在转基因拟南芥中,LE-ACS6启动子还表现响应外源生长素处理、伤害处理等多种刺激因子的特点。

The LE-ACS6 gene encodes ACC synthase, the key enzyme of ethylene biosynthesis pathway. Accumulation of LE-ACS6 transcripts is concomitant with the system 1 ethylene production in the pre-climacteric tomato fruit, and both are down regulated by exogenous ethylene treatment. To elucidate the possible role of system 1 ethylene in plant development and investigate the promoter tissue specificity of LE-ACS6 gene, stable transformation of Arabidopsis with a LE-ACS6 promoter-GUS fusion construct by Agrobacterium method has been done. Histochemical localization of GUS activity and β-glucuronidase enzyme assay in transgenic LE-ACS6::GUS plants showed strong expression of GUS in cotyledons and hypocot-yls of 6 d seedlings, but no GUS activity was detected in roots (Fig.2A). The GUS activity of 6 d seedling was increased significantly when treated with NAA 10-4mol/L (Fig.3). In 40 d rosette leaf LE-ACS6 promoter driven GUS gene was predominantly expressed in mature leaves. Lower level of GUS expression was detected in younger and older leaves (Fig.2B). Wounding was found to increase GUS gene expression in transgenic leaves (Fig.4). Again, exogenous NAA was found to increase the GUS activity in wounded leaf tissue (Fig.4). Strong staining reaction was observed in the top part of rapidly growing stems (Fig.2C). In different developmental stages of Arabidopsis seeds, 'mature green' pods were strongly stained, but 'ripening fruits' were not colored (Fig.2D). These observations are concomitant with the system 1 ethylene production, suggesting a popular mechanism in regulating ethylene biosynthesis in different plants, at least in tomato and Arabidopsis.