赤霉素(GA)是一种在干细胞伸长、细胞分裂、细胞分化、种子发芽和开花等关键发育过程中起重要作用的植物激素,赤霉素生物合成抑制剂广泛用于提高作物生长速度。加快作物生长是纤维、纸浆、木材和生物质生产行业欲实现的一个重要目标。以色列Tel Aviv大学的一组研究人员发现,沉默烟草模式植物中的一种赤酶素失活酶能显著改善作物的生长特性。他们的这项研究发表于Plant Biotechnology Journal。
该组研究人员以赤酶素GA 2氧化酶为研究对象,这种物质能在过表达GA 20氧化酶的情况下在植物体内积累,GA 20氧化酶能催化赤霉素生物合成途径的限速步骤。与过表达GA 20氧化酶的品系相比,沉默GA 2氧化酶的品系生长速度更快,植株更高,因此使GA 2氧化酶沉默的方法更适用于木材和纤维行业。（生物谷Bioon.com）
生物谷推荐原始出处：
Plant Biotechnology Journal 13 Jan 2010 10.1111/j.1467-7652.2009.00480.x
Enhancing plant growth and fiber production by silencing GA 2-oxidase
Jonathan Dayan, Maayan Schwarzkopf 1 , Adi Avni and Roni Aloni*
Department of Plant Sciences, Tel Aviv University, Tel Aviv 69978, Israel
Enhancing plant height and growth rates is a principal objective of the fiber, pulp, wood and biomass product industries. Many biotechnological systems have been established to advance that task with emphasis on increasing the concentration of the plant hormone gibberellin, or on its signalling. In this respect, the most studied gibberellin biosynthesis enzyme is the GA 20-oxidase which catalyses the rate limiting step of the pathway. Overexpression of the gene resulted in an excessively high activity of the gibberellin deactivating enzyme, GA 2-oxidase. Consequently, this feedback regulation limits the intended outcome. We assume that silencing GA 2-oxidase transcription would abolish this antithetical effect, thereby allowing greater gibberellin accumulation. Here, we show that silencing the gibberellin deactivating enzyme in tobacco model plants results in a dramatic improvement of their growth characteristics, compared with the wild type and GA 20-oxidase over-expressing plants. Moreover, the number of xylem fiber cells in the silenced lines exceeded that of GA 20-oxidase over-expressing plants, potentially, making GA 2-oxidase silencing more profitable for the wood and fiber industries. Interestingly, crossing GA 20-oxidase over-expressing plants with GA 2-oxidase silenced plants did not yield consequential additive effects. Our findings unveil the benefits of silencing GA 2-oxidase to substantially increase tobacco growth and fiber production, which suggest using this approach in cultivated forest plantations and industrial herbaceous plants, worldwide.
