Mashabela Manamele D, Tugizimana Fidele, Steenkamp Paul A, Piater Lizelle A, Dubery Ian A, Mhlongo Msizi I
Research Centre for Plant Metabolomics, Department of Biochemistry, University of Johannesburg, Johannesburg, South Africa.
International Research and Development Division, Omnia Group, Ltd., Johannesburg, South Africa.
Front Microbiol. 2022 Aug 25;13:971836. doi: 10.3389/fmicb.2022.971836. eCollection 2022.
The rhizosphere is a highly complex and biochemically diverse environment that facilitates plant-microbe and microbe-microbe interactions, and this region is found between plant roots and the bulk soil. Several studies have reported plant root exudation and metabolite secretion by rhizosphere-inhabiting microbes, suggesting that these metabolites play a vital role in plant-microbe interactions. However, the biochemical constellation of the rhizosphere soil is yet to be fully elucidated and thus remains extremely elusive. In this regard, the effects of plant growth-promoting rhizobacteria (PGPR)-plant interactions on the rhizosphere chemistry and above ground tissues are not fully understood. The current study applies an untargeted metabolomics approach to profile the rhizosphere exo-metabolome of wheat cultivars generated from seed inoculated (bio-primed) with (T22) and strains and to elucidate the effects of PGPR treatment on the metabolism of above-ground tissues. Chemometrics and molecular networking tools were used to process, mine and interpret the acquired mass spectrometry (MS) data. Global metabolome profiling of the rhizosphere soil of PGPR-bio-primed plants revealed differential accumulation of compounds from several classes of metabolites including phenylpropanoids, organic acids, lipids, organoheterocyclic compounds, and benzenoids. Of these, some have been reported to function in plant-microbe interactions, chemotaxis, biocontrol, and plant growth promotion. Metabolic perturbations associated with the primary and secondary metabolism were observed from the profiled leaf tissue of PGPR-bio-primed plants, suggesting a distal metabolic reprograming induced by PGPR seed bio-priming. These observations gave insights into the hypothetical framework which suggests that PGPR seed bio-priming can induce metabolic changes in plants leading to induced systemic response for adaptation to biotic and abiotic stress. Thus, this study contributes knowledge to ongoing efforts to decipher the rhizosphere metabolome and mechanistic nature of biochemical plant-microbe interactions, which could lead to metabolome engineering strategies for improved plant growth, priming for defense and sustainable agriculture.
根际是一个高度复杂且生物化学性质多样的环境，它促进了植物 - 微生物以及微生物 - 微生物之间的相互作用，这个区域存在于植物根系与大块土壤之间。多项研究报道了根际微生物的植物根系分泌物和代谢物分泌情况，这表明这些代谢物在植物 - 微生物相互作用中起着至关重要的作用。然而，根际土壤的生化组成尚未完全阐明，因此仍然极其难以捉摸。在这方面，植物促生根际细菌（PGPR）与植物的相互作用对根际化学和地上组织的影响尚未完全了解。当前的研究采用非靶向代谢组学方法来分析由接种（生物引发）了 （T22）和 菌株的种子产生的小麦品种的根际外代谢组，并阐明PGPR处理对地上组织代谢的影响。化学计量学和分子网络工具被用于处理、挖掘和解释所获取的质谱（MS）数据。对PGPR生物引发植物的根际土壤进行的全球代谢组分析揭示了几类代谢物中化合物的差异积累，包括苯丙烷类、有机酸、脂质、有机杂环化合物和苯类化合物。其中，一些已被报道在植物 - 微生物相互作用、趋化性、生物防治和植物生长促进中发挥作用。从PGPR生物引发植物的叶组织分析中观察到与初级和次级代谢相关的代谢扰动，这表明PGPR种子生物引发诱导了远端代谢重编程。这些观察结果为一个假设框架提供了见解，该框架表明PGPR种子生物引发可以诱导植物的代谢变化，从而导致诱导系统反应以适应生物和非生物胁迫。因此，本研究为正在进行的破译根际代谢组和植物 - 微生物生化相互作用的机制性质的努力贡献了知识，这可能会导致改善植物生长、防御引发和可持续农业的代谢组工程策略。
