Metabolic regulation of the maize rhizobiome by benzoxazinoids

First author: T. E. Anne Cotton; Affiliations: The University of Sheffield (谢菲尔德大学): Sheffield, UK

Corresponding author: Jurriaan Ton

The rhizobiome is an important regulator of plant growth and health. Plants shape their rhizobiome communities through production and release of primary and secondary root metabolites. Benzoxazinoids (BXs) are common tryptophan-derived secondary metabolites in grasses that regulate belowground and aboveground biotic interactions. In addition to their biocidal activity, BXs can regulate plant–biotic interactions as semiochemicals or within-plant defence signals. However, the full extent and mechanisms by which BXs shape the root-associated microbiome has remained largely unexplored. Here, we have taken a global approach to examine the regulatory activity of BXs on the maize root metabolome and associated bacterial and fungal communities. Using untargeted mass spectrometry analysis in combination with prokaryotic and fungal amplicon sequencing, we compared the impacts of three genetic mutations in different steps in the BX pathway. We show that BXs regulate global root metabolism and concurrently influence the rhizobiome in a root type-dependent manner. Correlation analysis between BX-controlled root metabolites and bacterial taxa suggested a dominant role for BX-dependent metabolites, particularly flavonoids, in constraining a range of soil microbial taxa, while stimulating methylophilic bacteria. Our study supports a multilateral model by which BXs control root–microbe interactions via a global regulatory function in root secondary metabolism.

根瘤菌是调控植物生长和健康的重要因素。植物通过产生和释放一些初生和次生的根代谢产物来塑造本身所处环境的根瘤菌群落。苯并噁唑嗪酮BXs是一类草本植物中常见的来源于色氨酸的次生代谢物，调控地上和地下的生物互作。BXs除了具有生物学作用以外，还能够作为信息化学物质或者是植物内部的防御信号调控植物-生物互作。然而，具体是哪一个BX通过什么样的方式来影响植物根相关的微生物组还不清楚。本文，作者系统研究了BXs对于玉米根代谢组及相关细菌和真菌群落的调控活性。利用非靶向的质谱分析结合原核生物和真菌扩增子测序，作者比较了BX通路上三个不同阶段的三个遗传突变的影响。作者发现BXs调控整体的根代谢，并且同时会通过依赖于根类型的方式影响根瘤菌。BX控制的根代谢物与细菌种类之间的相关性分析显示BX相关代谢物，尤其是类黄酮在限制土壤微生物种类方面占有主要作用，同时能够刺激嗜甲基细菌。本文的研究显示多个BXs通过整体调控根的次生代谢物从而调控根-微生物互作。

通讯：Jurriaan Ton (https://www.sheffield.ac.uk/aps/staff-and-students/acadstaff/ton)

个人简介：1996年，荷兰乌得勒支大学，生物学学士；2001年，荷兰乌得勒支大学，植物病理学博士。

研究方向：植物如何通过自身的免疫系统适应不同的环境胁迫。

doi: https://doi.org/10.1038/s41396-019-0375-2

Journal: The ISME Journal

Published date: February 22, 2019