Light affects tissue patterning of the hypocotyl in the shade-avoidance response

First author: Esther Botterweg-Paredes; Affiliations: University of Copenhagen (哥本哈根大学): Thorvaldsensvej, Denmark

Corresponding author: Stephan Wenkel

Plants have evolved strategies to avoid shade and optimize the capture of sunlight. While some species are tolerant to shade, plants such as Arabidopsis thaliana are shade-intolerant and induce elongation of their hypocotyl to outcompete neighboring plants. We report the identification of a developmental module acting downstream of shade perception controlling vascular patterning. We show that Arabidopsis plants react to shade by increasing the number and types of water-conducting tracheary elements in the vascular cylinder to maintain vascular density constant. Mutations in genes affecting vascular patterning impair the production of additional xylem and also show defects in the shade-induced hypocotyl elongation response. Comparative analysis of the shade-induced transcriptomes revealed differences between wild type and vascular patterning mutants and it appears that the latter mutants fail to induce sets of genes encoding biosynthetic and cell wall modifying enzymes. Our results thus set the stage for a deeper understanding of how growth and patterning are coordinated in a dynamic environment.

植物演化出了避免阴影遮挡的策略，从而最大化的捕获阳光。尽管有些物种可以耐荫，但如拟南芥等植物却不能耐荫，其通过诱导下胚轴伸长，来与邻近植物竞争阳光。本文中，作者鉴定了控制维管模式建成的阴影感知的下游发育模块。作者发现拟南芥植株通过增加维管柱（vascular cylinder）中作用于导水的管状分子（tracheary element）的数量和类型，来维持维管密度恒定，从而对阴影作出反应。影响维管模式建成的基因发生突变会形成额外的木质部，并且阴影诱导的下胚轴生长响应也存在缺陷。通过阴影诱导的转录组比较分析显示在野生型与维管模式建成突变体之间存在明显的差异，并且后者中不能像野生型那样诱导编码细胞壁生物合成和修饰相关酶的基因集。本文的研究结果为进一步深入理解在动态环境条件下植物生长与组织模式建成之间是如何协调统一的奠定了基础。

Author Summary

Shade sensitive plants such as Arabidopsis respond to shade by growing tall in order to maximize their access to sunlight. We find that the REVOLUTA (REV) and KANADI1 (KAN1) transcription factors which are primarily involved in patterning the early leaf, impinge on the regulation of WUSCHEL HOMEOBOX4 (WOX4), another transcription factor involved in vascular development. The regulation of WOX4 leads to an increase of the number of water-conducting xylem cells in response to shade. Consequently, mutations in the genes encoding either REV, KAN1 or WOX4 are impaired in their ability to grow tall in shade. Thus, we have uncovered a connection between basic patterning and adaptive growth.

拟南芥等阴影敏感植株响应于遮阴，会通过长得更高来最大化其获取阳光的能力。作者发现参与早期叶片模式建成的REV和KAN1转录因子会影响另外一个参与维管发育到的转录因子WOX4的基因调控。响应于阴影，WOX4基因的调控会增加导水木质部细胞的数量。因此，编码REV、KAN1或者WOX4任何一个基因的突变会在植物响应阴影时的高生长方面存在缺陷。因此，我们揭示了一个植物中基础组织模式建成与适应性生长之间的关联。

通讯：Michael Muszynski (https://manoa.hawaii.edu/ctahr/tpss/faculty?id=1035)

个人简介：1985年，托莱多大学，学士；1992年，爱荷华州立大学，博士。

研究方向：植物生长发育的分子调控机制。

doi: https://doi.org/10.1371/journal.pgen.1008678

Journal: PLoS Genetics

Published date: March 23, 2020