식물의 뿌리와 하배축의 옥신 분포와 굴중성 반응에 관한 연구

Abstract

Plant gravitropic response, regulated by the plant hormone auxin, shows opposite directions in roots and stems. In this study, we examined how the auxin distribution in roots and hypocotyls changes by gravistimulation in Arabidopsis. Auxin distribution was tracked by DR5-GFP fluorescence under gravitropic experimental conditions, designed for the gravitropism analysis in both roots and hypocotyls of Arabidopsis. When the seedlings were subjected to gravistimulation, auxin mainly accumulated in the lower sections of both roots and hypocotyls. Especially in the lower section of hypocotyls, the treatment group’s fl uorescence intensity increased by more than twice compared to that of the control group. We also measured the overall fluorescence intensity in the entire hypocotyl region, and found to increase by 40% in the treatment group compared to the control group. These fi ndings suggest that the absolute amount of auxin in the hypocotyls increased by gravistimulation. To confirm the increase in auxin concentration, we quantitatively checked the expression of DR5-GUS reporter gene, which is another marker for auxin levels. The results confi rmed that the reporter gene expression level increased significantly, particularly in the gravistimulated hypocotyls. Taken together, this study suggests that gravistimulation not only causes the redistribution of auxin but also overall increase in the concentration of auxin in Arabidopsis.