Nutrient and Microbiome Mediated Plant Soil Feed-back in Domesticated and Wild Andropogoneae. rhizosphere metagenome

Plants influence the abiotic and biotic environment of the rhizosphere, affecting plant performance through plant soil feedback (PSF). We compared the strength of nutrient and microbe-mediated PSF and its implications for plant performance in domesticated and wild grasses with a fully crossed greenhouse PSF experiment using four inbred maize genotypes (Zea mays ssp. mays b58, B73-wt, B73-rth3, and HP301), teosinte (Z. mays ssp. parviglumis), and two wild prairie grasses (Andropogon gerardii and Tripsacum dactyloides) to condition soils for three feedback species (maize B73-wt, teosinte, Andropogon gerardii). We found evidence of negative PSF based on growth, phenotypic traits, and foliar nutrient concentrations for maize B73-wt, which grew slower in maize-conditioned soil than prairie grass-conditioned soil. In contrast, teosinte and A. gerardii showed few consistent feedback responses. Both rhizobiome and nutrient-mediated mechanisms were implicated in PSF. Based on 16S rRNA gene amplicon sequencing, the rhizosphere bacterial community composition differed significantly after conditioning by prairie grass and maize plants, and the final soil nutrients were significantly influenced by conditioning, more so than by the feedback plants. These results suggest PSF-mediated soil domestication in agricultural settings can develop quickly and reduce crop productivity mediated by PSF involving changes to both the soil rhizobiomes and nutrient availability.

植物可调控根际（rhizosphere）的非生物与生物环境，并通过植物-土壤反馈（plant soil feedback, PSF）影响自身生长表现。本研究采用完全交叉设计的温室PSF实验，以4个玉米自交系基因型（*Zea mays* ssp. *mays* b58、B73-wt、B73-rth3与HP301）、类蜀黍（*Z. mays* ssp. *parviglumis*）及2种野生草原禾草（须芒草*Andropogon gerardii*、美洲摩擦禾*Tripsacum dactyloides*）作为土壤驯化植物，以玉米B73-wt、类蜀黍与须芒草作为反馈受体植物，对比分析了养分介导与微生物介导的PSF强度，及其对栽培与野生禾本科植物生长表现的影响。
研究结果显示，玉米B73-wt存在负向PSF效应：基于其生长速率、表型性状与叶片养分浓度的分析表明，相较于草原禾草驯化的土壤，玉米驯化土壤中玉米B73-wt的生长速率显著更慢。与之相对，类蜀黍与须芒草则未表现出稳定一致的反馈响应。PSF的作用机制同时涉及根际微生物组与养分介导两条途径。基于16S rRNA基因扩增子测序结果，草原禾草与玉米驯化后的根际细菌群落组成存在显著差异；最终土壤养分水平亦受驯化处理的显著调控，且其影响程度大于反馈植物本身的作用。上述结果表明，农业生产环境中由PSF介导的土壤驯化过程可快速发生，并通过改变土壤根际微生物组与养分有效性，削弱作物的生产性能。