Project description:Ethylene plays major roles in adaptive growth of rice plants in water-saturated soil; however, ethylene signaling in rice is largely unclear. Here, we report identification and characterization of ethylene-response mutants based on distinct ethylene-response phenotypes of dark-grown rice seedlings.
Project description:Ethylene plays major roles in adaptive growth of rice plants in water-saturated soil; however, ethylene signaling in rice is largely unclear. Here, we report identification and characterization of ethylene-response mutants based on distinct ethylene-response phenotypes of dark-grown rice seedlings.
Project description:Ethylene plays major roles in adaptive growth of rice plants in water-saturated soil; however, ethylene signaling in rice is largely unclear. Here, we report identification and characterization of ethylene-response mutants based on distinct ethylene-response phenotypes of dark-grown rice seedlings.
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:Phosphorus (P) is an essential nutrient for plant growth and productivity. Due to soil fixation, however, phosphorus availability in soil is rarely sufficient to sustain high crop yields. Fertilizers are widely used to circumvent the limited bioavailability of phosphate (Pi) which led to a scenario of excessive soil P in agricultural soils. Whereas adaptive responses to Pi deficiency have been deeply studied, less is known about how plants adapt to Pi excess and how Pi excess might affect disease resistance. Here, we show that high Pi fertilization in rice plants, and subsequent Pi accumulation in leaves, enhances susceptibility to infection by Magnaporthe oryzae, the causal agent of the rice blast disease. Equally, MIR399f overexpression causes an increase in Pi content in rice leaves which results in enhanced susceptibility to M. oryzae. During pathogen infection, a weaker activation of defense-related genes occurs in rice plants accumulating Pi in leaves, a response that is in agreement with the phenotype of blast susceptibility observed in these plants. These data support that Pi, when in excess, compromises defense mechanisms in rice while demonstrating that miR399 functions as a negative regulator of rice immunity. The two signaling pathways, Pi signaling and defense signaling, must operate in a coordinated manner in controlling disease resistance. This information provides a basis to understand the molecular mechanisms involved in immunity in rice plants grown under a high Pi fertilization regime, an aspect that should be considered in management of the rice blast disease
Project description:To improve our understanding of soil moisture stress, we performed RNA-Seq analysis using roots from four-week-old rice seedlings grown in soil that had been subjected o drought conditions for 2 to 3 d. From the upregulated genes, we found a T-DNA insertional mutant of rice phytochrome B (OsPhyB) that negatively regulates plant’s degree of tolerance to water deficiencies through its control of ascorbate peroxidase and catalase mediating ROS processing machinery besides the control of total leaf area and stomatal density as previously reported.
Project description:Roots make the first contact with the soil environment and are the first responders of stress. These root behaviors are quantifiable and adaptive. The response of rice varieties in mechanical and salinity stress was measured in a novel experimental setup that mimics the soil environment. We analyzed the response of roots by means of SAC (Stress Adaptation Coefficient) in 28 rice varieties that include high-yield salt tolerant varieties as well as geographically isolated native rice varieties. cDNA microarray of IR64 root-tip shows about 6000 common transcripts to be differentially regulated among the two stresses and common pathways were identified. Overall, our study indicates that there is an important commonality in the molecular basis of salt and mechanical stress and presents an easy-to-perform early establishment stress screen for rice varieties.