Effects of probiotic consortia on plant metabolites are associated with soil indigenous microbiota and fertilization regimes

Introducing probiotics to soil is a sustainable way to stimulate the production of plant metabolites. However, the soil-resident microbes may compromise the efficiency of probiotics. To date, it remains challenging to integrate the effects of probiotics on plant performance with soil microbiome changes. Using Cyclocarya paliurus (Batal.) Iljinsk as a model medicinal plant and two types of probiotic consortia combined with organic fertilizer at three levels (low: 0.5, medium: 1.0, and high: 1.5 kg center dot plant & xe213; 1), we examined the impacts of three fertilization regimes (O: organic fertilizer, OMF: O coupled with Bacillus megaterium and Pseudomonas fluorescens, OCB: O coupled with Azotobacter chroococcum and Azospirillum brasilense) on plant metabolites and nutrient stoichiometry after three-year applications and identified the key soil microbes relating to the accumulation of plant metabolites via generalized joint attribute model (GJAM) analysis. Our results indicated that the concentration of flavonoids reached 36.9 mg center dot g & xe213; 1 in OCB treatment at a low level, and 30.0 mg center dot g & xe213; 1 in OMF treatment at a medium level, both were significantly higher than that in O treatment (25.8 mg center dot g & xe213; 1 on average). Furthermore, the accumulations of metabolites were associated with plant nutrient acquisition and C: N: P stoichiometry. GJAM analysis showed that higher fertilizer levels restricted the influence of probiotic consortia on the variance of plant-soil-microbe system, with fewer differences observed between fertilizer types. Specific soil microbes were predicted as potential indicators that may assist or impede the effects of probiotics on plant metabolite production. The predictions were further tested in a comparative pot experiment, and the effects of common indicators in both pot and field experiments were consistently associated with probiotics' addition. This study reveals that the effects of probiotics on plant metabolites are associated with fertilization regimes and soil-indigenous microbes. Identifying microbial indicators will help to understand the probiotics' effects and further improve plant productivity.

Automated summary

Introducing probiotics to soil can stimulate plant metabolite production, but soil-resident microbes may affect the efficiency of probiotics. This study investigated the effects of different fertilization regimes and soil microbes on the accumulation of plant metabolites. The results showed that fertilization regimes and soil microbes play a crucial role in influencing plant metabolite production. Identifying microbial indicators can help understand the effects of probiotics and improve plant productivity.