Table_1_Critical transition of soil microbial diversity and composition triggered by plant rhizosphere effects.docx

Over the years, microbial community composition in the rhizosphere has been extensively studied as the most fascinating topic in microbial ecology. In general, plants affect soil microbiota through rhizodeposits and changes in abiotic conditions. However, a consensus on the response of microbiota traits to the rhizosphere and bulk soils in various ecosystems worldwide regarding community diversity and structure has not been reached yet. Here, we conducted a meta-analysis of 101 studies to investigate the microbial community changes between the rhizosphere and bulk soils across various plant species (maize, rice, vegetables, other crops, herbaceous, and woody plants). Our results showed that across all plant species, plant rhizosphere effects tended to reduce the rhizosphere soil pH, especially in neutral or slightly alkaline soils. Beta-diversity of bacterial community was significantly separated between into rhizosphere and bulk soils. Moreover, r-strategists and copiotrophs (e.g. Proteobacteria and Bacteroidetes) enriched by 24-27% in the rhizosphere across all plant species, while K-strategists and oligotrophic (e.g. Acidobacteria, Gemmatimonadete, Nitrospirae, and Planctomycetes) decreased by 15-42% in the rhizosphere. Actinobacteria, Firmicutes, and Chloroflexi are also depleted by in the plant rhizosphere compared with the bulk soil by 7-14%. The Actinobacteria exhibited consistently negative effect sizes across all plant species, except for maize and vegetables. In Firmicutes, both herbaceous and woody plants showed negative responses to rhizosphere effects, but those in maize and rice were contrarily enriched in the rhizosphere. With regards to Chloroflexi, apart from herbaceous plants showing a positive effect size, the plant rhizosphere effects were consistently negative across all other plant types. Verrucomicrobia exhibited a significantly positive effect size in maize, whereas herbaceous plants displayed a negative effect size in the rhizosphere. Overall, our meta-analysis exhibited significant changes in microbial community structure and diversity responding to the plant rhizosphere effects depending on plant species, further suggesting the importance of plant rhizosphere to environmental changes influencing plants and subsequently their controls over the rhizosphere microbiota related to nutrient cycling and soil health.

长期以来，根际（rhizosphere）微生物群落组成作为微生物生态学领域极具吸引力的核心研究主题之一，已得到广泛且深入的探讨。通常而言，植物可通过根际沉积作用以及非生物环境条件的改变，对土壤微生物群落产生调控作用。然而，针对全球各类生态系统中，微生物群落多样性与结构特征对根际与非根际（bulk soil）土壤的响应规律，学界尚未形成统一共识。为此，本研究针对101项已发表的相关研究开展荟萃分析（meta-analysis），旨在探究不同植物类群（包括玉米、水稻、蔬菜、其他农作物、草本植物与木本植物）的根际与非根际土壤微生物群落差异。研究结果表明，在所有植物类群中，植物根际效应均会降低根际土壤pH值，这一现象在中性或弱碱性土壤中尤为突出。细菌群落的β多样性（beta-diversity）在根际与非根际土壤间存在显著分化。此外，在所有植物类群中，r-策略者与富营养型微生物（如变形菌门（Proteobacteria）、拟杆菌门（Bacteroidetes））在根际土壤中的丰度显著富集24%-27%；而K-策略者与寡营养型微生物（如酸杆菌门（Acidobacteria）、芽单胞菌门（Gemmatimonadetes）、硝化螺旋菌门（Nitrospirae）与浮霉菌门（Planctomycetes））在根际土壤中的丰度降低15%-42%。放线菌门（Actinobacteria）、厚壁菌门（Firmicutes）与绿弯菌门（Chloroflexi）在植物根际土壤中的丰度同样较非根际土壤降低7%-14%。放线菌门在所有植物类群中均表现出显著负效应量，仅玉米与蔬菜类群除外。对于厚壁菌门而言，草本与木本植物的根际效应使其丰度呈下降趋势，但玉米与水稻类群的厚壁菌门丰度却在根际土壤中显著富集。关于绿弯菌门，除草本植物表现出正效应量外，其余所有植物类群的根际效应均使其丰度呈显著下降趋势。疣微菌门（Verrucomicrobia）在玉米类群中表现出显著正效应量，而在草本植物的根际土壤中则表现为负效应量。总体而言，本荟萃分析表明，植物根际效应对微生物群落结构与多样性的影响因植物类群而异，这进一步凸显了植物根际在调控与植物相关的环境变化中的关键作用——这些环境变化可通过养分循环与土壤健康相关过程，进而影响根际微生物群落的动态平衡。