Effects of rare earth elements on bacteria in rhizosphere, root, phyllosphere and leaf of soil–rice ecosystem

Abstract

The effects of rare earth mining on rice biomass, rare earth element (REE) content and bacterial community structure was studied through pot experiment. The research shows that the REE content in rice roots, shoots and grains was significantly positive correlated with that in soil, and the dry weight of rice roots, shoots and grains was highly correlated with soil physical and chemical properties, nutrient elements and REE contents; The exploitation of rare earth minerals inhibited a-diversity of endophytic bacteria in rhizosphere, root, phyllosphere and leaf of rice, significantly reduced the abundance index, OTU number, Chao, Ace index and also significantly reduced the diversity index–Shannon index, and also reduced uniformity index: Pielou’s evenness index, which caused β-diversity of bacteria to be quite different. The exploitation of rare earth minerals reduces the diversity of bacteria, but forms dominant bacteria, such as Burkholderia, Bacillus, Buttiauxella, Acinetobacter, Bradyrhizobium, Candida koribacter, which can degrade the pollutants formed by exploitation of rare earth minerals, alleviate the compound pollution of rare earth and ammonia nitrogen, and also has the function of fixing nitrogen and resisting rare earth stress; The content of soil available phosphorus in no-mining area is lower, and the dominant bacteria of Pantoea formed in such soil, which has the function of improving soil phosphorus availability. Rare earth elements and physical and chemical properties of soil affect the community structure of bacteria in rhizosphere and phyllosphere of rice, promote the parallel movement of some bacteria in rhizosphere, root, phyllosphere and leaf of rice, promote the construction of community structure of bacteria in rhizosphere and phyllosphere of rice, give full play to the growth promoting function of Endophytes, and promote the growth of rice. The results showed that the exploitation of rare earth minerals has formed the dominant endophytic bacteria of rice and ensured the yield of rice in the mining area, however, the mining of mineral resources causes the compound pollution of rare earth and ammonia nitrogen, which makes REE content of rice in mining area significantly higher than that in non-mining area, and the excessive rare earth element may enter the human body through the food chain and affect human health, so the food security in the REE mining area deserves more attention.

Effects of different straw returning amounts and fertilizer conditions on bacteria of rice’s different part in rare earth mining area

“…DNA concentration and purity were measured using the micro ultraviolet–visible spectrophotometer, NanoDrop2000, and then stored in a refrigerator at − 20 °C for subsequent 16S rRNA gene analysis. Experimental methods were according to Zhang et al 30 .…”

“…Sample data that were too small were removed and UNITE database was used for species annotation. The experimental method was according to Zhang et al 30 .…”

“…Microorganisms in plants are one of the key factors affecting plant growth, nutrition, and health. They help plants obtain nutrients, inhibit plant pathogens, and resist biological and abiotic stresses 30 . When Streptomyces albidoflavus Osilf 2 was inoculated in conditions of greenhouse and field, the rice disease index decreased by 18.0% and 19.6%, respectively, indicating that Osilf 2 has significant biocontrol activity and host defense stimulation ability 31 .…”

“…Zhang et al . showed that rice straw returning soil affected the form of soil rare earth elements and the physical and chemical properties of the soil, affected the rhizosphere and phyllosphere bacteria of rice, and the community structure of bacteria in rice roots and leaves, thus affected the growth promoting function of rice endophytic bacteria and rice growth, but the mechanism was very complex 30 . It is not clear how endophytic bacteria affect the REE content of rice in the mining area.…”

Trophic Transfer and Toxic Potency of Rare Earth Elements along a Terrestrial Plant–Herbivore Food Chain

“…15,48 This effect on the snail gut microbiome was not directly due to the fact that the snails were exposed indirectly to the REEs. Previous studies have shown that REEs directly affected the bacteria in the phyllosphere and leaf of a soil−rice system 49 and changed the metabolites in the leaves of plants. 50 However, our study, for the first time, revealed the indirect effects of REEs on microbiota through the food chain.…”