氮掺杂石墨烯量子点对拟南芥主根生长方向的影响

Effect of Nitrogen-doped Graphene Quantum Dots on Growth Direction of Primary Root in Arabidopsis thaliana

石墨烯量子点(GQDs)在电化学生物传感器、生物成像和生物医学等领域具有巨大的应用潜力,在公众和环境中的暴露程度也越来越高,近年来其生物安全性备受关注。截至目前,有关石墨烯量子点对植物生长发育影响的研究较少。该文从细胞和分子水平探究了氮掺杂石墨烯量子点(N-GQDs)处理对拟南芥(Arabidopsis thaliana)主根生长方向的影响。结果表明,N-GQDs能够被根摄取,并通过维管束运输。50-100 mg·L^(-1) N-GQDs处理可改变主根的生长方向,使其朝着远离培养基的方向发生弯曲。研究发现,N-GQDs处理导致根尖小柱细胞中淀粉粒的积累减少,生长素外排载体PIN3的表达量降低,小柱细胞中的PIN3重新定位到远离培养基一侧的细胞外侧膜(即朝向空气),促进根尖生长素的不对称分布,从而引发主根朝着远离培养基的方向弯曲生长,以避开较高浓度的N-GQDs环境。研究结果为进一步阐明N-GQDs处理改变根生长方向的机制提供了重要线索,同时也为N-GQDs的生物安全性评价提供参考依据。

Graphene quantum dots(GQDs)have substantial application potentials in various fields such as electrochemical biosensor,bioimaging and biomedicine.Therefore,with the increasing exposure to the public and environment,their biosafety has aroused increasing concerns in recent years.So far,the influence of GQDs on the growth and development of plants is still poorly understood.In this study,we investigated the influence of nitrogen-doped GQDs(N-GQDs)treatment on the growth direction of primary root in Arabidopsis thaliana at cellular and molecular levels.We found that the N-GQDs were absorbed by roots and transported via vascular bundles.After the N-GQDs treatment at the concentration of 50-100 mg·L^(-1),the growth direction of primary roots was changed,curving towards the outside of the culture medium.Because of the N-GQDs treatment,the starch granule accumulation of columnar cells was reduced,the abundance of auxin efflux carrier PIN3 was repressed,and the PIN3 in columnar cells was relocated to outer lateral membrane distant from the culture medium(towards the air),which resulted in the asymmetric auxin distribution in the root tips and the curved growth of primary roots towards a direction distant from the medium in order to run away from the high-concentration N-GQDs environment.The study results provide a reference direction for exploring the possible coping mechanism of plants with N-GQDs treatment,and also provide corresponding data for biosafety evaluation of N-GQDs.