Project description:Arsenic (As) bioavailability in the rice rhizosphere is influenced by many microbial interactions, particularly by metal-transforming functional groups at the root-soil interface. This study was conducted to examine As-transforming microbes and As-speciation in the rice rhizosphere compartments, in response to two different water management practices (continuous and intermittently flooded), established on fields with high to low soil-As concentration. Microbial functional gene composition in the rhizosphere and root-plaque compartments were characterized using the GeoChip 4.0 microarray. Arsenic speciation and concentrations were analyzed in the rhizosphere soil, root-plaque, porewater and grain samples. Results indicated that intermittent flooding significantly altered As-speciation in the rhizosphere, and reduced methyl-As and AsIII concentrations in the pore water, root-plaque and rice grain. Ordination and taxonomic analysis of detected gene-probes indicated that root-plaque and rhizosphere assembled significantly different metal-transforming functional groups. Taxonomic non-redundancy was evident, suggesting that As-reduction, -oxidation and -methylation processes were performed by different microbial groups. As-transformation was coupled to different biogeochemical cycling processes establishing functional non-redundancy of rice-rhizosphere microbiome in response to both rhizosphere compartmentalization and experimental treatments. This study confirmed diverse As-biotransformation at root-soil interface and provided novel insights on their responses to water management, which can be applied for mitigating As-bioavailability and accumulation in rice grains.
Project description:The response to moderate and heavy drought of two Solanum tuberosum ssp. Andigena varieties, Sullu (NP 03.03) and SA 2563 (NP 03.01), planted in rain- and soil water protected fields in the Peruvian highlands are compared. Previous experiments indicate that Sullu has a greater capacity for yield maintenance under drought than SA 2563. Both clones have similar morphological properties, vegetative periods and rooting depths, so it can be assumed that the cause for increased drought tolerance of clone NP 03.03 is rather due to physiological or biochemical mechanisms, than to drought escape by deep rooting or earliness. Sullu and SA 2563 were planted in a random block design with 5 plants per bloc and 7 repetitions per treatment. Treatments: (1) drought stress, (2) irrigated control The plants were drip-irrigated in both treatments until tuberization (until day 84 after planting). Subsequently, the irrigation was stopped in the drought field, but continued in the control field. The soil moisture content in the control field was kept near field capacity. Planting date: October 05 2004 Start of drought treatment (during tuberization, 84 days after planting): December 28 2004 First sampling (soil water potential: -0.3 mPa 114 days after planting): January 27 2005 Second sampling (soil water potential –0.6 MPa, 134 days after planting): February 15 2005 Harvest: March 19 2005 (165 days after planting) The experimental design includes gene expression analysis in leaves, roots and stolons at two time points, when soil water potential reaches -0.3 and –0.6 MPa. Gene expression changes will be set in relation with physiological and agronomical data obtained in the same experiment. Keywords: Direct comparison
2007-09-01 | GSE8243 | GEO
Project description:Alternate irrigation with reclaimed water
Project description:The response to moderate and heavy drought of two Solanum tuberosum ssp. Andigena varieties, Sullu (NP 03.03) and SA 2563 (NP 03.01), planted in rain- and soil water protected fields in the Peruvian highlands are compared. Previous experiments indicate that Sullu has a greater capacity for yield maintenance under drought than SA 2563. Both clones have similar morphological properties, vegetative periods and rooting depths, so it can be assumed that the cause for increased drought tolerance of clone NP 03.03 is rather due to physiological or biochemical mechanisms, than to drought escape by deep rooting or earliness. Sullu and SA 2563 were planted in a random block design with 5 plants per bloc and 7 repetitions per treatment. Treatments: (1) drought stress, (2) irrigated control The plants were drip-irrigated in both treatments until tuberization (until day 84 after planting). Subsequently, the irrigation was stopped in the drought field, but continued in the control field. The soil moisture content in the control field was kept near field capacity. Planting date: October 05 2004 Start of drought treatment (during tuberization, 84 days after planting): December 28 2004 First sampling (soil water potential: -0.3 mPa 114 days after planting): January 27 2005 Second sampling (soil water potential –0.6 MPa, 134 days after planting): February 15 2005 Harvest: March 19 2005 (165 days after planting) The experimental design includes gene expression analysis in leaves, roots and stolons at two time points, when soil water potential reaches -0.3 and –0.6 MPa. Gene expression changes will be set in relation with physiological and agronomical data obtained in the same experiment. Keywords: Direct comparison 19 hybs total
Project description:Metaproteomics can be used to study functionally active biofilm-based bacterial populations in reclaimed water distribution systems, which in turn result in bacterial regrowth that impacts the water quality. However, existing protein extraction methods have differences in their protein recovery and have not been evaluated for their efficacies in reclaimed water biofilm samples. In this study, we first evaluated six different protein extraction methods with diverse chemical and physical properties on a mixture of bacterial cell culture. Based on a weighting scores-based evaluation, the extraction protocols in order of decreasing performance are listed as B-PER > RIPA > PreOmics > SDS > AllPrep > Urea. The highest four optimal methods on cell culture were further tested against treated wastewater non-chlorinated and chlorinated effluent biofilms. In terms of protein yield, our findings showed that RIPA performed the best; however, the highest number of proteins were extracted from SDS and PreOmics. Furthermore, SDS and PreOmics worked best to rupture gram-positive and gram-negative bacterial cell walls. Considering the five evaluation factors, PreOmics obtained highest weighted score, indicating its potential effectiveness in extracting proteins from biofilms. This study provides the first insight into evaluating protein extraction methods to facilitate metaproteomics for complex reclaimed water matrices.
Project description:GCMS datasets for the soil depth manuscript
Abstract
Two factors that are well-known to influence soil microbiomes include the depth of the soil as well as the level of moisture. Previous works have demonstrated that climate change will increase the incidence of drought in soils, but it is unknown how fluctuations in moisture availability affect soil microbiome composition and functioning down the depth profile. Here, we investigated soil and wheatgrass rhizosphere microbiomes in a common field setting under four different irrigation regimes and three depths. We demonstrated that there is a significant interactive effect, where fluctuations in soil moisture more strongly influence soil microbiomes at the surface layer than in deeper layers, including for soil community composition, diversity, and for functional profiles. Meanwhile, in rhizosphere communities the influence of irrigation was similar across the different depths, although there were slight discrepancies between the two cultivars of wheatgrass used. The lessened response of deeper soil microbiomes to changes in irrigation may be due to higher incidence of slow-growing, stress-resistant microbes.
Project description:A cultivation facility that can assist users in controlling the soil water condition is needed for accurately phenotyping plants under drought stress in an artificial environment. Here we report the Internet of Things (IoT)-based pot system controlling optional treatment of soil water condition (iPOTs), an automatic irrigation system that mimics the drought condition in a growth chamber. The Wi-Fi-enabled iPOTs system allows water supply from the bottom of the pot, based on the soil water level set by the user, and automatically controls the soil water level at a desired depth. The iPOTs also allows users to monitor environmental parameters, such as soil temperature, air temperature, humidity, and light intensity, in each pot. To verify whether the iPOTs mimics the drought condition, we conducted a drought stress test on rice varieties and near-isogenic lines, with diverse root system architecture, using the iPOTs system installed in a growth chamber. Similar to the results of a previous drought stress field trial, the growth of shallow-rooted rice accessions was severely affected by drought stress compared with that of deep-rooted accessions. The microclimate data obtained using the iPOTs system increased the accuracy of plant growth evaluation. Transcriptome analysis revealed that pot positions in the growth chamber had little impact on plant growth. Together, these results suggest that the iPOTs system represents a reliable platform for phenotyping plants under drought stress.
Project description:Bacterial wilt caused by Ralstonia solanacearum is a lethal, soil-borne disease of tomato. Control of the disease with chemicals and crop rotation is insufficient, because the pathogen is particularly well adapted for surviving in the soil and rhizosphere. Therefore, cultivar resistance is the most effective means for controlling bacterial wilt, but the molecular mechanisms of resistance responses remain unclear. We used microarrays to obtain the characteristics of the gene expression changes that are induced by R. solanacearum infection in resistant cultivar LS-89 and susceptible cultivar Ponderosa.
Project description:To identify genes that are drought-responsive we conducted drought (soil water depletion) experiments on 3-month-old *P*. *trichocarpa *clonal plants. The plants undergo five different stages based on the appearance of their shoots and leaves during the drought experiments. Stage I: The shoot and leaves are green, and the leaves are well-spread. Stage II: The leaves are droopy. Stage III: The shoot is droopy, and the leaves are partially dry. Stage IV: The leaves are brown and totally dry. Stage V: The shoot is brown. With fully irrigation, the soil water content is 74% and the xylem water content is 80.6%. Plants in Stage III (Day 5) are under a mild drought state. The soil and xylem water content in Stage III dropped to 33% and 75.3%, respectively. Stage IV (Day 6-10) is a severe drought state where the soil and xylem water content continued decreasing to 29% and 74.3%, respectively in Day 7. The stressed plants from Stage I-IV could all recover in 3 days after rehydration, but the plants in Stage V could not recover after rehydration.