Project description:To investigate the effects of organic fertilizer replacing chemical fertilizer on the growth and development of barley (Kunlun-14), a pot experiment was conducted. The study examined the impacts of different ratios of organic fertilizer replacing chemical fertilizer nitrogen (0%, 40%, 100%, denoted as OFR0, OFR40, OFR100, respectively) on the growth characteristics, leaf carbon-nitrogen balance, and nitrogen metabolism enzyme activities of barley.
Project description:Arbuscular mycorrhizal (AM) fungi contribute to plant nutrient uptake in systems managed with reduced fertilizer inputs such as organic agriculture and natural ecosystems by extending the effective size of the rhizosphere and delivering mineral. Connecting the molecular study of the AM symbiosis with agriculturally- and ecologically-relevant field environments remains a challenge and is a largely unexplored research topic. This study utilized a cross-disciplinary approach to examine the transcriptional, metabolic, and physiological responses of tomato (Solanum lycopersicum) AM roots to a localized patch of nitrogen (N). A wild-type mycorrhizal tomato and a closely-related nonmycorrhizal mutant were grown at an organic farm in soil that contained an active AM extraradical hyphal network and soil microbe community. The majority of genes regulated by upon enrichment of nitrogen were similarly expressed in mycorrhizal and nonmycorrhizal roots, suggesting that the primary response to an enriched N patch is mediated by mycorrhiza-independent root processes. However where inorganic N concentrations in the soil were low, differential regulation of key tomato N transport and assimilation genes indicate a transcriptome shift towards mycorrhiza-mediated N uptake over direct root supplied N. Furthermore, two novel mycorrhizal-specific tomato ammonium transporters were also found to be regulated under low N conditions. A conceptual model is presented integrating the transcriptome response to low N and highlighting the mycorrhizal-specific ammonium transporters. These results enhance our understanding of the role of the AM symbiosis in sensing and response to an enriched N patch, and demonstrate that transcriptome analyses of complex plant-microbe-soil interactions provide a global snapshot of biological processes relevant to soil processes in organic agriculture. 30 samples were analyzed. There were 2 genotypes (wildtype and mutant) and 3 treatments (two N treatments and a water control) for a total of 6 groups. Each group had 5 biological replicates.
Project description:The spread of antibiotic resistance genes (ARG) into agricultural soils, products, and foods severely limits the use of organic fertilizers in agriculture. In this study, experimental land plots were fertilized, sown, and harvested for two consecutive agricultural cycles using either mineral or three types of organic fertilizers: sewage sludge, pig slurry, or composted organic fraction of municipal solid waste. The analysis of the relative abundances of more than 200,000 ASV (Amplicon Sequence Variants) allowed the identification of a small, but significant (<10%) overlap between soil and fertilizer microbiomes, particularly in soils sampled the same day of the harvest (post-harvest soils). Loads of clinically relevant ARG were significantly higher (up to 100 fold) in fertilized soils relative to the initial soil. The highest increases corresponded to post-harvest soils treated with organic fertilizers, and they correlated with the extend of the contribution of fertilizers to the soil microbiome. Edible products (lettuce and radish) showed low, but measurable loads of ARG (sul1 for lettuces and radish, tetM for lettuces). These loads were minimal in mineral fertilized soils, and strongly dependent on the type of fertilizer. We concluded that at least part of the observed increase on ARG loads in soils and foodstuffs were actual contributions from the fertilizer microbiomes. Thus, we propose that adequate waste management and good pharmacological and veterinarian practices may significantly reduce the potential health risk posed by the presence of ARG in agricultural soils and plant products.
Project description:Arbuscular mycorrhizal (AM) fungi contribute to plant nutrient uptake in systems managed with reduced fertilizer inputs such as organic agriculture and natural ecosystems by extending the effective size of the rhizosphere and delivering mineral. Connecting the molecular study of the AM symbiosis with agriculturally- and ecologically-relevant field environments remains a challenge and is a largely unexplored research topic. This study utilized a cross-disciplinary approach to examine the transcriptional, metabolic, and physiological responses of tomato (Solanum lycopersicum) AM roots to a localized patch of nitrogen (N). A wild-type mycorrhizal tomato and a closely-related nonmycorrhizal mutant were grown at an organic farm in soil that contained an active AM extraradical hyphal network and soil microbe community. The majority of genes regulated by upon enrichment of nitrogen were similarly expressed in mycorrhizal and nonmycorrhizal roots, suggesting that the primary response to an enriched N patch is mediated by mycorrhiza-independent root processes. However where inorganic N concentrations in the soil were low, differential regulation of key tomato N transport and assimilation genes indicate a transcriptome shift towards mycorrhiza-mediated N uptake over direct root supplied N. Furthermore, two novel mycorrhizal-specific tomato ammonium transporters were also found to be regulated under low N conditions. A conceptual model is presented integrating the transcriptome response to low N and highlighting the mycorrhizal-specific ammonium transporters. These results enhance our understanding of the role of the AM symbiosis in sensing and response to an enriched N patch, and demonstrate that transcriptome analyses of complex plant-microbe-soil interactions provide a global snapshot of biological processes relevant to soil processes in organic agriculture.