Project description:Understanding the mechanisms underlying the establishment of invasive plants is critical in community ecology. According to a widely accepted theory, plant-soil-microbe interactions mediate the effects of invasive plants on native species, thereby affecting invasion success. However, the roles and molecular mechanisms associated with such microbes remain elusive. Using high throughput sequencing and a functional gene microarray, we found that soil taxonomic and functional microbial communities in plots dominated by Ageratina adenophora developed to benefit the invasive plant. There were increases in nitrogen-fixing bacteria and labile carbon degraders, as well as soil-borne pathogens in bulk soil, which potentially suppressed native plant growth. Meanwhile, there was an increase of microbial antagonism in the A. adenophora rhizosphere, which could inhibit pathogenicity against plant invader. These results suggest that the invasive plant A. adenophora establishes a self-reinforcing soil environment by changing the soil microbial community. It could be defined as a ‘bodyguard/mercenary army’ strategy for invasive plants, which has important insights for the mitigation of plant invasion.
Project description:Metagenome data from soil samples were collected at 0 to 10cm deep from 2 avocado orchards in Channybearup, Western Australia, in 2024. Amplicon sequence variant (ASV) tables were constructed based on the DADA2 pipeline with default parameters.
Project description:Clipping (i.e., harvesting aboveground plant biomass) is common in agriculture and for bioenergy production. However, microbial responses to clipping in the context of climate warming are poorly understood. We investigated the interactive effects of grassland warming and clipping on soil properties, plant and microbial communities, in particular microbial functional genes. Clipping alone did not change the plant biomass production, but warming and clipping combined increased the C4 peak biomass by 47% and belowground net primary production by 110%. Clipping alone and in combination with warming decreased the soil carbon input from litter by 81% and 75%, respectively. With less carbon input, the abundances of genes involved in degrading relatively recalcitrant carbon increased by 38-137% in response to either clipping or the combined treatment, which could weaken the long-term soil carbon stability and trigger a positive feedback to warming. Clipping alone also increased the abundance of genes for nitrogen fixation, mineralization and denitrification by 32-39%. The potentially stimulated nitrogen fixation could help compensate for the 20% decline in soil ammonium caused by clipping alone, and contribute to unchanged plant biomass. Moreover, clipping tended to interact antagonistically with warming, especially on nitrogen cycling genes, demonstrating that single factor studies cannot predict multifactorial changes. These results revealed that clipping alone or in combination with warming altered soil and plant properties, as well as the abundance and structure of soil microbial functional genes. The aboveground biomass removal for biofuel production needs to be re-considered as the long-term soil carbon stability may be weakened.
Project description:Soil microorganisms act as gatekeepers for soil-atmosphere carbon exchange by balancing the accumulation and release of soil organic matter. However, poor understanding of the mechanisms responsible hinders the development of effective land management strategies to enhance soil carbon storage. Here we empirically test the link between microbial ecophysiological traits and topsoil carbon content across geographically distributed soils and land use contrasts. We discovered distinct pH-controls on microbial mechanisms of carbon accumulation. Land use intensification in low-pH soils that increased pH above a threshold (~ 6.2) lead to carbon loss through increased decomposition following alleviation of acid-retardation of microbial growth. However, loss of carbon with intensification in near neutral-pH soils was linked to decreased microbial biomass and reduced growth efficiency that was, in turn, related to tradeoffs with stress alleviation and resource acquisition. Thus, less intensive management practices in near neutral-pH soils have more potential for carbon storage through increased microbial growth efficiency; whereas, in acidic soils microbial growth is a bigger constraint on decomposition rates.
Project description:Widespread organic pollutants such as BTEX (benzene, toluene, ethylbenzene, and xylene) are traditionally considered to enhance soil carbon loss through mineralization and ecotoxicity. Challenging this paradigm, we reveal that BTEX can stimulate microbial carbon chain elongation (CE)—a previously overlooked carbon fixation pathway—thereby reshaping soil carbon dynamics. Through phased amplicon sequencing, metagenomics, and metaproteomics, we demonstrate that BTEX exerts bidirectional regulation on CE at both taxonomic and molecular levels. Specifically, BTEX selectively enriches Clostridium_sensu_stricto_12 and Rummelibacillus, while suppressing Acinetobacter, a key CE contributor in natural soils. BTEX also inhibits Petrimonas, a syntrophic degrader of medium-chain fatty acids (MCFAs), promoting MCFAs accumulation. Moreover, BTEX-degrading bacteria establish cooperative interactions with CE bacteria, facilitating the sequestration of carbon as MCFAs rather than complete mineralization to CO₂, with Bacillus bridging both metabolic roles. At the molecular level, BTEX enhances CE by accelerating substrate uptake and acetyl-CoA flux into the reverse β-oxidation (RBO) pathway. Multi-omics analysis revealed that BTEX downregulates fatty acid biosynthesis (FAB), another pathway of CE, through fabR, acrR, and fadR while maintaining NADH availability to relieve Rex-mediated inhibition of the key RBO enzyme gene bcd. However, excessive BTEX disrupts metabolic homeostasis and suppresses CE activity. Collectively, our findings redefine the ecological implications of aromatic hydrocarbon contamination by uncovering its capacity to modulate anaerobic carbon fixation and retention in soil microbial communities. This work highlights a previously unrecognized link between pollutant degradation and biogenic carbon sequestration, with broader implications for understanding soil biogeochemical resilience under anthropogenic pressure.