Project description:Understanding the environmental factors that shape microbial communities is crucial, especially in extreme environments, like Antarctica. Two main forces were reported to influence Antarctic soil microbes: birds and plants. Both birds and plants are currently undergoing unprecedented changes in their distribution and abundance due to global warming. However, we need to clearly understand the relationship between plants, birds and soil microorganisms. We therefore collected rhizosphere and bulk soils from six different sampling sites subjected to different levels of bird influence and colonized by Colobanthus quitensis and Deschampsia antarctica in the Admiralty Bay, King George Island, Maritime Antarctic. Microarray and qPCR assays targeting 16S rRNA genes of specific taxa were used to assess microbial community structure, composition and abundance and analyzed with a range of soil physico-chemical parameters. The results indicated significant rhizosphere effects in four out of the six sites, including areas with different levels of bird influence. Acidobacteria were significantly more abundant in soils with little bird influence (low nitrogen) and in bulk soil. In contrast, Actinobacteria were significantly more abundant in the rhizosphere of both plant species. At two of the sampling sites under strong bird influence (penguin colonies), Firmicutes were significantly more abundant in D. antarctica rhizosphere but not in C. quitensis rhizosphere. The Firmicutes were also positively and significantly correlated to the nitrogen concentrations in the soil. We conclude that the microbial communities in Antarctic soils are driven both by bird and plants, and that the effect is taxa-specific.
Project description:Boron is essential for plants, and boron availability in soil is an important determinant of agricultural production. Boron availability in soil is limited at many regions in the world, including Japan. Under boron deficient conditions, leaf expansion and root elongation, apical dominance, flower development,and fruit and seed sets are inhibited. In this work, we analyzed the mRNA expression of genes containing AUGUAA motif in their 5′-UTR, which is induced by boron. We used microarrays to detail the global gene expression underlying boron deficiency in roots.
2013-11-13 | GSE52208 | GEO
Project description:World Wide Bed Bug Virome Study
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
Project description:Despite the global importance of forests, it is virtually unknown how their soil microbial communities adapt at the phylogenetic and functional level to long term metal pollution. Studying twelve sites located along two distinct gradients of metal pollution in Southern Poland revealed that both community composition (via MiSeq Illumina sequencing of 16S rRNA genes) and functional gene potential (using GeoChip 4.2) were highly similar across the gradients despite drastically diverging metal contamination levels. Metal pollution level significantly impacted microbial community structure (p = 0.037), but not bacterial taxon richness. Metal pollution altered the relative abundance of specific bacterial taxa, including Acidobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, Firmicutes, Planctomycetes and Proteobacteria. Also, a group of metal resistance genes showed significant correlations with metal concentrations in soil, although no clear impact of metal pollution levels on overall functional diversity and structure of microbial communities was observed. While screens of phylogenetic marker genes, such as 16S rRNA, provided only limited insight into resilience mechanisms, analysis of specific functional genes, e.g. involved in metal resistance, appeared to be a more promising strategy. This study showed that the effect of metal pollution on soil microbial communities was not straightforward, but could be filtered out from natural variation and habitat factors by multivariate statistical analysis and spatial sampling involving separate pollution gradients.
Project description:Nitrogen availability in the soil is a major determinant of crop yield. While the application of fertilizer can substantially increase the yield on poor soils, it also causes nitrate pollution of water resources and high costs for farmers. Increasing the nitrogen use efficiency in crop plants is a necessary step to implement low input agricultural systems. We exploited the genetic diversity present in the world-wide Arabidopsis thaliana population to study adaptive growth patterns and changes in gene expression associated with chronic low nitrate stress, with the aim to identify biomarkers associated with good plant performance under low nitrate availability. Transcription and epigenetic factors were identified as important players in the adaptatiion to limited nitrogen in a global gene expression analysis using the Affymetrix ATH1 chip.