背景回顾：The plant hormone auxin serves as central regulator of growth and development. Auxin transportersin the plasma membrane are assumed to define tissue-level patterns of auxin distribution. 

提出问题：However, auxin is small enough to diffuse through the plasmodesmata that connect neighboring cells, presenting an alternative pathway, whose contribution to auxin transport remained largely unexplored. 

方法手段：Here, photoactivation microscopy was used to measure the capacity for small-molecule diffusion in the epidermis of Arabidopsis thaliana leaves. 

初步发现：In the elongated epidermis cells covering the midrib and petiole, the plasmodesmata-mediated cell-wall permeability was found to be several times higher in the longitudinal than in the transverse direction. 

深入试验：The physiological relevance of this asymmetry was tested through quantification of the shade-avoidance response, which depends on auxin transport from the leaf tip to the petiole in the abaxial side of the leaf, with the hypothesis that directionality of diffusion supplements transporter-mediated auxin movement. 

结果解析：Triggering the response by auxin application at the tip led to stronger leaf movement in wild-type plants than in gsl8 mutants, which lack the callose synthase necessary to establish directionality. The results match the predictions of a mathematical model of auxin transport based on the permeabilities measured in wild-type and mutant plants.

结论展望：It is concluded that plasmodesmata permeability can be selectively modulated within a plant cell and that the conferred directionality in diffusion can influence the tissue-specific distribution patterns of small molecules, like auxin.

摘  要

植物激素生长素是植物生长和发育的核心调控因子。质膜中的生长素转运体是植物组织水平上生长素分布模式的决定因子。然而，生长素分子尺寸十分微小，足以通过连接邻近细胞的胞间连丝（plasmodesmata），因此为生长素的转运提供了替代途径，但该途径对于生长素转运的作用还有待研究。本文中，作者通过光活化显微镜测量了拟南芥叶片表皮中小分子扩散的能力。在覆盖中脉和叶柄和伸长型表皮细胞中，胞间连丝介导的细胞壁通透性在纵向上要比横向上高出好几倍。作者假设扩散的方向性补充了由转运蛋白介导的生长素移动，即上文作者观测到的不对称性具有生理相关性，作者进一步通过量化依赖于叶片内背侧由叶尖到叶柄的生长素转运的避荫响应来测试了这一假设。通过向叶尖外施生长素所诱导的响应在野生型拟南芥中导致的叶片移动比在gsl8突变体中更为强烈，而该突变体缺少了一个用于建立方向性的胼胝质合酶。作者基于在野生型和突变体植株中测量的通透性数据，构建了生长素转运的数学模型，其所获得的预测结果与上文的试验结果相符。因此，未来可以通过选择性的调控植物细胞的胞间连丝通透性，从而决定扩散的方向性，最终影响生长素等小分子的组织特异性分布模式。

2008年，德国柏林洪堡大学，学士；

2012年，哥本哈根大学，博士；

2012-2015年，哥本哈根大学，博士后。

研究方向：植物中糖转运的遗传调控机制。