Project description:Transition of Bacterial Community Structure in Upland Soil Treated with LMC, a Soil Amendment Containing Low Molecular Weight Chitin
Project description:Chitin soil amendment is known to improve soil quality, plant growth and plant stress resilience, but the underlying mechanisms are not well understood. In this study, we monitored chitin’s effect on lettuce physiology every two weeks through an eight-week growth period, analyzed the early transcriptional reprogramming and related metabolomic changes of lettuce, in response to crab chitin treatment in peat-based potting soil. In commercial growth conditions, chitin amendment still promoted lettuce growth, increased chlorophyll content, the number of leaves and crop head weight from week six. The flavonoid content in lettuce leaves was altered as well, showing an increase at week two but a decrease from week six. Transcriptomic analysis showed that over 300 genes in lettuce root were significant differentially expressed after chitin soil treatment. Gene Ontology-term (GO) enrichment analysis revealed statistical overrepresentation of GO terms linked to photosynthesis, pigment metabolic process and phenylpropanoid metabolic process. Further analysis of the differentially expressed genes (DEGs) showed that the flavonoid pathway is mostly upregulated whereas the bifurcation of upstream phenylpropanoid pathway towards lignin biosynthesis is mostly downregulated. Metabolomic analysis revealed the upregulation of salicylic acid, chlorogenic acid, ferulic acid, and p-coumaric acid in chitin treated lettuce seedlings. These phenolic compounds mainly influence the phenylpropanoid biosynthesis pathway and may play important roles in plant defense reactions. Our results suggest that chitin soil amendments might activate induced resistance by priming lettuce plants and promote lettuce growth via transcriptional changes.
Project description:The effects of two years' winter warming on the overall fungal functional gene structure in Alaskan tundra soil were studies by the GeoChip 4.2 Resuts showed that two years' winter warming changed the overall fungal functional gene structure in Alaskan tundra soil.
2019-03-07 | GSE127899 | GEO
Project description:Soil fungal community structure and function with biochar amendment
Project description:Analysis of 14-day-old Columbia-0 seedlings treated with chito-tetramer.Results provide insight into the signaling pathways involved in plant devlopment in response to the four-mer. Chitin is the second biopolymer most abundant at nature, after cellulose, forming part of insect exosqueletons, crustacean shells, krill and fungal spores where is present as a high molecular weight molecule. Previously we showed that Arabidopsis defense related clusters of genes were induced by high molecular weight chitin (CHH) or 8mer oligosaccharides similarly (Ramonell et al., 2005), some of those genes were essential for effective defense against phytopathogenic fungus (Berrocal-Lobo et al., 2010). At this work we show that differentially, a chitin oligosaccharide of lower molecular weight (4mer), induce genes in Arabidopsis related principally to vegetative growth, development and carbon and nitrogen metabolism.
Project description:Anthropogenic activities have dramatically increased the inputs of reactive nitrogen (N) into terrestrial ecosystems, with potentially important effects on the soil microbial community and consequently soil C and N dynamics. Our analysis of microbial communities in soils subjected to 14 years of 7 g N m-2 year-1 Ca(NO3)2 amendment in a Californian grassland showed that the taxonomic composition of bacterial communities, examined by 16S rRNA gene amplicon sequencing, was significantly altered by nitrate amendment, supporting the hypothesis that N amendment- induced increased nutrient availability, yielded more fast-growing bacterial taxa while reduced slow-growing bacterial taxa. Nitrate amendment significantly increased genes associated with labile C degradation (e.g. amyA and xylA) but had no effect or decreased the relative abundances of genes associated with degradation of more recalcitrant C (e.g. mannanase and chitinase), as shown by data from GeoChip targeting a wide variety of functional genes. The abundances of most N cycling genes remained unchanged or decreased except for increases in both the nifH gene (associated with N fixation), and the amoA gene (associated with nitrification) concurrent with increases of ammonia-oxidizing bacteria. Based on those observations, we propose a conceptual model to illustrate how changes of functional microbial communities may correspond to soil C and N accumulation.
Project description:Genome-wide microarray analysis was performed using RNA extracted from soil cultures of Streptomyces coelicolor A3(2) in the presence or absence of chitin. The vast majority of genes in chitin and amino sugar metabolism, as well as many other genes for carbon and energy, nitrogen and sulfur metabolism, were differentially expressed in response to addition of chitin. Moreover, the gene expressions of eight gene clusters for secondary metabolites were also significantly up-regulated in the chitin amended soil. To reveal the role of a pleiotropic transcriptional regulator, DasR, which has been reported to be involved in regulation of chitin metabolism, antibiotic production and morphological differentiation, the gene expression patterns of wild type and dasR mutant in soil amended with chitin were compared by microarray analysis. The dasR mutation resulted in up-regulation of four antibiotic gene clusters and down-regulation of chitin metabolism.
Project description:Chitin, a polymer of N-acetyl-glucosamne, is a component of the cell walls of many plant fungal pathogens. During the infection process, the released chitin fragments (such as chitooctaose) from fungal cell walls by plant enzymes can trigger plant defense response and gene activation. The current work studies the regulation of Arabidopsis genes by the purified chitin fragment chitooctaose. We used the Affymetric Arabidopsis whole gene arrays to study the gene expression caused by chitin (chitooctaose). Keywords: chitooctaose vs water treatments, with 3 biological replicates