Gene Expression Patterns in Potato Roots Associated with Greater Plant Growth at Low Phosphate Concentrations in the Rhizosphere
ABSTRACT: There are both financial and environmental reasons for optimising the use of phosphorus (P) fertilisers in potato production. One strategy to effect this is to develop genotypes with greater P use efficiency (PUE), which is generally defined as yield divided by the P available to the crop. In this article we report that potato (Solanum tuberosum L.) genotypes differ in their PUE, expressed both as yield in the field and as shoot biomass when grown hydroponically. When grown hydroponically, PUE was strongly correlated with P uptake efficiency (PUpE, defined as shoot P content), but not with physiological P utilisation efficiency (PUtE, defined as shoot biomass divided by shoot P content). Gene expression in roots differed between potato genotypes, and changed with P supply. A common transcriptional response to reduced P supply was determined in roots of four potato genotypes. This response comprised genes encoding enzymes involved in increasing rhizosphere P availability, phosphate transport, P-sparing metabolism, replacement of phospholipids in cell membranes, and various transcription factors. A specific transcriptional response associated only with roots of genotypes with high yields in the absence of P-fertiliser application in the field (Maris Piper and Stirling) was also identified. Genes involved in this response encoded various transcription factors, proteins facilitating water, solute and auxin transport, and enzymes involved in polyamine metabolism and the biosynthesis of tropane alkaloids.
Project description:Masson pine (Pinus massoniana) has evolved some adaptations for growth in low P soils. To elucidate these mechanisms, we investigated global gene expression profiles of the masson pine responding to long-term phosphorus starvation and different Pi levels (P1, 0.01 mM P; P2, 0.06 mM P). Analysis used phosphorus-sufficient treatment RNA as control samples for comparison to the experimental samples (P1 and P2) taken at 12, 24, 48 and 60 day. Indirect comparisons were made across multiple arrays with raw data pulled from different channels for data analysis and comparison to the control data.
Project description:affy_agro-bi_medicago - Identification of genes from the model legume Medicago truncatula whose expression is affected by the plant nitrogen status, with or without inoculation with the symbiotic bacteria Sinorhizobium meliloti. - Comparison of the supernodulant, nitrogen-insensitive, sunn-2 mutant with the A17 wild type genotype.-The plant root systems of plants were split into two parts, each one being installed in a separate compartment. For the “S” treatment, one part was supplied with 10 mM NH4NO3 while the other part was supplied with a nitrogen-free nutrient solution. For the “L” treatment, one part was supplied 0.5mM NO3- and the other part was supplied with the nitrogen free solution. Eight biological materials (designated AL, AS, SL, SS, IL, IS, NIL, NIS), with three biological repeats for each, were collected and analyzed. The effects of the S and L conditions were investigated on wild-type A17 (AL vs. AS) and sunn-2 mutant plants (SL vs. SS); one set of A17 plants was inoculated with Sinorhizobium meliloti (IL vs. IS), harvested at four days post inoculation and compared to non-inoculated plants (NIL vs. NIS). Keywords: growth in nitrogen-sufficient (s) vs. nitrogen-limited (l) conditions 18 arrays - Medicago
Project description:Martian regolith (unconsolidated surface material) is a potential medium for plant growth in bioregenerative life support systems during manned missions on Mars. However, hydrated magnesium sulfate mineral levels in the regolith of Mars can reach as high as 10 wt%, and would be expected to be highly inhibitory to plant growth. A global approach was used to identify novel genes with potential to enhance tolerance to high MgSO4 stress. The early Arabidopsis root transcriptome response to elevated concentrations of magnesium sulfate was characterized in col-0, and also between col-0 and the mutant line cax1-1 – a mutant relatively tolerant of high levels of MgSO4•7H2O in soil solution. After 3 weeks of growth under hydroponic conditions, Arabidopsis thaliana col-0 roots were exposed to a basic nutrient solution (0.25 g/L MES, 1/16x MS, pH 5.7) with an additional 2.08 mM magnesium sulfate (total Ca:Mg ratio = 1:15) for 45 min., 90 min., or 180 min., while a col-0 control set was exposed to the basic nutrient solution without additional magnesium sulfate for 45 minutes. Arabidopsis thaliana cax1-1 roots were exposed to the basic nutrient solution with additional magnesium sulfate for 180 min. only. Four replicate containers were harvested for the control and each of the treatment sets, resulting in a total of 20 samples. Gene expression of the col-0 sets exposed to magnesium sulfate treatment for 45 min., 90 min., or 180 min. was compared to gene expression of the col-0 control set. Gene expression of the cax1-1 set exposed to magnesium sulfate treatment for 180 min. was compared to gene expression of the col-0 set exposed to magnesium sulfate treatment for 180 minutes.
Project description:Gene expression response of Populus plants subjected to hydroponic nitrogen manipulation was analyzed using the Affymetrix poplar genome microarrays. Experiment Overall Design: Populus fremontii x angustifolia genotypes were grown hydroponically with either 5 mM (N+) or 0.125 mM (N-) nitrogen. Young and mature leaves at Leaf Plastchron Index (LPI) 2 and 5, respectively, were sampled 4 weeks after the start of low N feeding. Two biological replicates were obtained for each condition.
Project description:Gene expression response of Populus plants subjected to hydroponic nitrogen manipulation was analyzed using the Affymetrix poplar genome microarrays. Experiment Overall Design: Populus fremontii x angustifolia genotypes were grown hydroponically with either 5 mM (N+) or 0.125 mM (N-) nitrogen. Young leaves at Leaf Plastchron Index (LPI) 2 were sampled 4 weeks after the start of low N feeding. Mature leaves at Leaf Plastchron Index (LPI) 5 were sampled 4 or 8 weeks after the start of low N feeding. Two biological replicates were obtained for each condition.
Project description:This study characterizes the transcriptomic alterations of Laccaria bicolor S238N during interaction with P. trichocarpa. Four time-points were analyzed, two weeks, four weeks , six weeks and twelve weeks after inoculation and compared to the transcriptome of free-living mycelium from Laccaria bicolor S238N We performed 16 hybridizations (NimbleGen) with samples derived from P.trichocarpa/L.bicolor mycorrhizal root tips. Samples were taken after 2,4,6 and 12 weeks of interaction (four biological replicates). These samples were compared to free-living mycelium from Laccaria bicolor S238N (three biological replicates). All samples were labeled with Cy3.
Project description:Plant cells contain different O-acetylserine(thiol)lyase (OASTL) enzymes involved in Cys biosynthesis and located in different subcellular compartments. These enzymes are made up of a complex variety of isoforms resulting in different subcellular Cys pools. To unravel the contribution of cytosolic Cys to plant metabolism, we characterized the knockout oas-a1.1 and osa-a1.2 mutants, deficient in the most abundant cytosolic OASTL isoform in Arabidposis thaliana. Total intracellular Cys and glutathione concentrations were reduced, and the glutathione redox state was shifted in favour of its oxidized form. Interestingly, the capability of the mutants to chelate heavy metals did not differ from that of the wild type, but the mutants have an enhanced sensitivity to Cd. With the aim of establishing the metabolic network most influenced by the cytosolic Cys pool, we used the ATH1 GeneChip for evaluation of differentially expressed genes in the oas-a1.1 mutant grown under non-stress conditions. The transcriptomic footprints of mutant plants had predicted functions associated with various physiological responses that are dependent on reactive oxygen species and suggested that the mutant was oxidatively stressed. To further elucidate the specific function(s) of the OAS-A1 isoform in the adaptation response to cadmium we extended the trasncriptome experiment to the wild type and oas-a1.1 mutant plants exposed to Cd. The comparison of transcriptomic profiles showed a higher proportion of genes with altered expression in the mutant than in the wild type, highlighting up-regulated genes identified as of the general oxidative stress response rather than metal-responsive genes. Wild type and oas-a1.1 mutant plants were grown hydroponically and, after a two-week acclimation period, the roots and shoots were harvested separately. Total RNA was then prepared and analyzed using the Affymetrix-Arabidopsis ATH1GeneChip array. Three biological replicates were performed for each sample. We made two different comparisons to classify the differently expressed genes in the mutant plant: oas-a1.1 roots versus wild-type roots and oas-a1.1 shoots versus wild-type shoots. Hydroponically-grown wild type and oas-a1.1 mutant plants were further treated with 50µM CdCl2 and 18h-treated-roots and 24h-treated-shoots were harvested. Total RNA was then prepared and analyzed using the Affymetrix-Arabidopsis ATH1GeneChip array. Three biological replicates were performed for each sample. Different comparisons were performed as follows: 18h Cd-treated wild type roots versus untreated wild type roots; 24h Cd-treated wild type shoots versus untreated wild type shoots; 18h Cd-treated oas-a1.1 roots versus untreated oas-a1.1 roots; 24h Cd-treated oas-a1.1 shoots versus untreated oas-a1.1 shoots; 18h Cd-treated oas-a1.1 roots versus 18h Cd-treated wild type roots; 24h Cd-treated oas-a1.1 shoots versus 24h Cd-treated wild type shoots