Demonstration of improved plant growth and biomass production by At1g73160 promoter-controlled root-preferential expression of the AtGA20ox gene

Abstract

Background: Overexpression of the GA20 oxidase gene has been a recent trend for improving plant growth and biomass. Constitutive expression of GA20ox has successfully improved plant growth and biomass in several plant species. However, the constitutive expression of this gene causes side-effects, such as reduced leaf size and stem diameters. To avoid these effects, different tissue-specific promoters were identified and employed for GA20ox overexpression. In this study, we demonstrated the potential of At1g, a root-preferential promoter, for GA20ox expression to enhance plant biomass in tobacco and Melia azedarach.Results: We examined the utility of the At1g promoter to drive the expression of a GUS (β-1,4-glucuronidase) reporter and the GA20ox gene in tobacco and Melia azedarach. Histochemical GUS assays in tobacco showed that At1g was a root-preferential promoter whose expression was particularly strong in root tips. The ectopic expression of the AtGA20ox gene under the control of the At1g promoter showed improved plant growth and biomass of both tobacco and M. azedarach transgenic plants compared to wild-type (WT) control plants. Stem length as well as stem and root fresh weights increased by up to 1.5-3 folds in transgenic tobacco and 2-fold in transgenic M. azedarach. Both tobacco and M. azedarach transgenic plants showed increases in the root xylem width and xylem over phloem ratio by 50%–100% compared to WT plants. Importantly, no significant differences in the leaf shape or size were observed between the At1g::AtGA20ox transgenic and WT plants. Moreover, transgenic M. azedarach showed a 135% increase in stem diameter although no change was found in transgenic tobacco.Conclusions: These results demonstrate the great utility of the At1g promoter for driving the AtGA20ox gene to induce growth and biomass improvements in woody plants and potentially some other plant species.

BIẾN NẠP VÀ ĐÁNH GIÁ CÁC DÒNG XOAN TA (Melia azedarach L.) MANG GEN GA20-OXIDASE ĐƯỢC ĐIỀU KHIỂN BỞI PROMOTER GmPrP2

“…Hiện nay, một số kết quả nghiên cứu tạo giống các cây lâm nghiệp sinh trưởng nhanh bằng kỹ thuật chuyển gen để tăng khả năng sinh tổng hợp chất điều tiết sinh trưởng gibberellin acid (GA) đã thu được một số kết quả khả quan [4], [5]. GA là hợp chất dạng diterpenes tham gia vào quá trình sinh trưởng và phát triển của cây do tác động đến quá trình phân chia tế bào như: nảy mầm, ra hoa, kéo dài thân... Gen mã hóa cho các enzyme tham gia sinh tổng hợp GA nội sinh có rất nhiều dạng khác nhau, enzyme GA20-oxidase được mã hóa bởi GA20 tham gia quá trình sinh tổng hợp GA trong tế bào thực vật.…”