Project description:<p>Biological nitrogen fixation by free-living bacteria and rhizobial symbiosis with legumes plays a key role in sustainable crop production. Here, we study how different crop combinations influence the interaction between peanut plants and their rhizosphere microbiota via metabolite deposition and functional responses of free-living and symbiotic nitrogen-fixing bacteria. Based on a long-term (8 year) diversified cropping field experiment, we find that peanut co-cultured with maize and oilseed rape lead to specific changes in peanut rhizosphere metabolite profiles and bacterial functions and nodulation. Flavonoids and coumarins accumulate due to the activation of phenylpropanoid biosynthesis pathways in peanuts. These changes enhance the growth and nitrogen fixation activity of free-living bacterial isolates, and root nodulation by symbiotic Bradyrhizobium isolates. Peanut plant root metabolites interact with Bradyrhizobium isolates contributing to initiate nodulation. Our findings demonstrate that tailored intercropping could be used to improve soil nitrogen availability through changes in the rhizosphere microbiome and its functions.</p>
2024-03-19 | MTBLS6537 | MetaboLights
Project description:Maize rhizosphere microbiome responds to precipitation under field conditions
Project description:Iron deficiency is a yield-limiting factor and a worldwide problem for crop production in many agricultural regions, particularly in aerobic and calcareous soils. Graminaceous species, like maize, improve Fe acquisition through the release of phytosiderophores (PS) into the rhizosphere and the following uptake of Fe(III)-PS complexes through specific transporters. Transcriptional profile obtained by roots 12-d-old maize plants under Fe starvation for 1 week (Fe-deficient; 19-d-old plants) were compared with the transcriptional profile obtained by roots of 12-d-old maize plants grown in a nutrient solution containing 100 μM Fe-EDTA for 1 week (Fe-sufficient; 19-d-old plants).
Project description:Intercropping is a vital technology in resource-limited agricultural systems with low inputs. Peanut/maize intercropping enhances iron (Fe) nutrition in calcareous soil. Proteomic studies of the differences in peanut leaves, maize leaves and maize roots between intercropping and monocropping systems indicated that peanut/maize intercropping not only improves Fe availability in the rhizosphere but also influences the levels of proteins related to carbon and nitrogen metabolism. Moreover, intercropping may enhance stress resistance in the peanut plant (Xiong et al. 2013b). Although the mechanism and molecular ecological significance of peanut/maize intercropping have been investigated, little is known about the genes and/or gene products in peanut and maize roots that mediate the benefits of intercropping. In the present study, we investigated the transcriptomes of maize roots grown in intercropping and monocropping systems by microarray analysis. The results enabled exploration differentially expressed genes in intercropped maize. Peanut (Arachis hypogaea L. cv. Luhua14) and maize (Zea mays L. cv. Nongda108) seeds were grown in calcareous sandy soil in a greenhouse. The soil was enhanced with basal fertilizers [composition (mg·kg−1 soil): N, 100 (Ca (NO3)2·4H2O); P, 150 (KH2PO4); K, 100 (KCl); Mg, 50 (MgSO4·7H2O); Cu, 5 (CuSO4·5H2O); and Zn, 5 (ZnSO4·7H2O)]. The experiment consisted of three cropping treatments: peanut monocropping, maize monocropping and intercropping of peanut and maize. After germination of peanut for 10 days, maize was sown. Maize samples were harvested after 63 days of growth of peanut plants based on the degree of Fe chlorosis in the leaves of monocropped peanut. The leaves of monocropped peanut plants exhibited symptoms of Fe-deficiency chlorosis at 63 days, while the leaves of peanut plants intercropped with maize maintained a green color.
Project description:Global warming substantially changes precipitation patterns in the Tibetan plateau, with projection of increased precipitation in southern and northern Tibet but decreased precipitation in the center. Understanding mechanisms of such changes in greenhouse gas emissions is of vital importance in predicting ecosystem feedbacks to climate changes. Nonetheless, it has been hampered by limited knowledge in soil microbial communities, one of the major drivers of greenhouse gas emission. Here, we report a field experiment simulating drying and wetting conditions in the Tibetan grassland. Our field site is located at the Haibei Alpine Grassland Ecosystem Research Station in the northeast of Tibet Plateau, China, and we employed GeoChip 5.0 180K to analyze microbial responses.
Project description:Iron (Fe) deficiency is a yield-limiting factor for a variety of field crops across the world and generally results from the interaction of limited soil Fe bioavailability and susceptible genotype cultivation. Tomato, a Strategy I, model plant for Fe deficiency, is an important economical crop. Tomato responses in order to improve Fe uptake are based on acidification of rhizosphere, reduction of Fe3+ to Fe2+ and transport of Fe2+ into the cells. Transcriptional profile obtained by roots (27-d) of 21-d-old tomato plants starved of iron for an additional week was compared with the transcriptional profile obtained for roots (27-d) of 21-d-old tomato plants grown for an additional week at 100 M-NM-<M Fe. Tomato plants were hydroponically grown in both cases. Three different biological replicates were used for each sample repeating the experiment three times. All samples were obtained pooling roots of six plants (27-d-old).
Project description:We found that primary root (PR) is more resistant to salt stress compared with crown roots (CR) and seminal roots (SR). To understand better salt stress responses in maize roots, six RNA libraries were generated and sequenced from primary root (PR), primary roots under salt stress (PR-salt) , seminal roots (SR), seminal roots under salt stress (SR-salt), crown roots (CR), and crown roots under salt stress (CR-salt). Through integrative analysis, we identified 444 genes regulated by salt stress in maize roots, and found that the expression patterns of some genes and enzymes involved in important pathway under salt stress, such as reactive oxygen species scavenging, plant hormone signal perception and transduction, and compatible solutes synthesis differed dramatically in different maize roots. 16 of differentially expressed genes were selected for further validation with quantitative real time RT-PCR (qRT-PCR).We demonstrate that the expression patterns of differentially expressed genes are highly diversified in different maize roots. The differentially expressed genes are correlated with the differential growth responses to salt stress in maize roots. Our studies provide deeper insight into the molecular mechanisms about the differential growth responses of different root types in response to environmental stimuli in planta.
Project description:On September 13, 2003, leaf tissue was collected from Andropogon gerardii growing in field plots under two precipitation variability treatments:ambient and altered (50% longer interval). cDNA was synthesized, labelled alternately with Cy3 and Cy5 and cross-hybridized to a maize microarray developed in the Schnable lab at Iowa State. Keywords: repeat sample
Project description:In this study, plants of maize inbred line B73 descended from two different sets of seed material grown for several generations either in the field or in the greenhouse were found to show a different growth phenotype and ionome under phosphate starvation conditions and moreover a different responsiveness towards mycorrhizal fungi of the species Glomus intraradices (syn: Rhizophagus irregularis).Transcriptome sequencing of three individuals from each set lent further support to the location of the introgression intervals and confirmed them to be fixed in all sequenced individuals. Moreover, we identified >120 genes differentially expressed between the two B73 lines.
Project description:Maize seedling transcriptome responses to six abiotic perturbations (heat, cold, darkness, desiccation, salt, UV-B) and 2 controls were analyzed Keywords: comparitive transcriptome profiling Tissues were grown at Stanford University during the summer of 2005. RNA was extracted and purified, cDNA generated, and amplified cRNA was labeled with Cy3 or Cy5 dyes from 4 biological replicates of each treatment. Each replicate was composed of a pool of 10 similarly treated whole seedlings (with the endosperm and kernel removed). Two types of biological controls were employed: 1) seedlings germinated under constant 26ºC temperature, with 16 h light and adequate water and 2) field grown juvenile leaf samples Field seedlings emerged on day 6 or 7.