Department of Agricultural Sciences, University of Federico II, Via Università 100, 80055, Portici, Italy; Southwest Florida Research and Education Center, Department of Soil, Water, and Ecosystem Sciences, Institute of Food and Agricultural Sciences, University of Florida, 2685 State Rd 29N, Immokalee, FL 34142, USA.
Department of Agricultural Sciences, University of Federico II, Via Università 100, 80055, Portici, Italy; Task Force on Microbiome Studies, University of Federico II, Naples, Italy.
Microbiol Res. 2024 Apr;281:127634. doi: 10.1016/j.micres.2024.127634. Epub 2024 Feb 1.
Nutrient deficiency, natural enemies and litter autotoxicity have been proposed as possible mechanisms to explain species-specific negative plant-soil feedback (PSF). Another potential contributor to negative PSF is the plant released extracellular self-DNA during litter decay. In this study, we sought to comprehensively investigate these hypotheses by using Arabidopsis thaliana (L.) Heynh as a model plant in a feedback experiment. The experiment comprised a conditioning phase and a response phase in which the conditioned soils underwent four treatments: (i) addition of activated carbon, (ii) washing with tap water, (iii) sterilization by autoclaving, and (iv) control without any treatment. We evaluated soil chemical properties, microbiota by shotgun sequencing and the amount of A. thaliana extracellular DNA in the differently treated soils. Our results showed that washing and sterilization treatments mitigated the negative PSF effect. While shifts in soil chemical properties were not pronounced, significant changes in soil microbiota were observed, especially after sterilization. Notably, plant biomass was inversely associated with the content of plant self-DNA in the soil. Our results suggest that the negative PSF observed in the conditioned soil was associated to increased amounts of soilborne pathogens and plant self-DNA. However, fungal pathogens were not limited to negative conditions, butalso found in soils enhancing A.thaliana growth. In-depth multivariate analysis highlights that the hypothesis of negative PSF driven solely by pathogens lacks consistency. Instead, we propose a multifactorial explanation for the negative PSF buildup, in which the accumulation of self-DNA weakens the plant's root system, making it more susceptible to pathogens.
养分缺乏、天敌和凋落物自毒作用被认为是解释物种特异性负植物-土壤反馈（PSF）的可能机制。负 PSF 的另一个潜在贡献者是植物在凋落物分解过程中释放的细胞外自身 DNA。在这项研究中，我们使用拟南芥（L.）Heynh 作为模型植物，在反馈实验中全面研究了这些假设。该实验包括一个调节阶段和一个响应阶段，在调节阶段，调节后的土壤经历了四种处理：（i）添加活性炭，（ii）用自来水冲洗，（iii）高压灭菌消毒，（iv）不进行任何处理作为对照。我们评估了土壤化学性质、通过高通量测序获得的微生物群和不同处理土壤中拟南芥细胞外 DNA 的含量。我们的结果表明，冲洗和消毒处理减轻了负 PSF 效应。虽然土壤化学性质的变化不明显，但观察到土壤微生物群发生了显著变化，尤其是在消毒后。值得注意的是，植物生物量与土壤中植物自身 DNA 的含量呈负相关。我们的结果表明，在调节土壤中观察到的负 PSF 与土壤中病原菌和植物自身 DNA 含量的增加有关。然而，真菌病原菌不仅限于负条件，也存在于促进拟南芥生长的土壤中。深入的多元分析强调，仅由病原菌驱动的负 PSF 假说缺乏一致性。相反，我们提出了一个关于负 PSF 积累的多因素解释，即自身 DNA 的积累削弱了植物的根系，使其更容易受到病原菌的侵害。
