Project description:Although urea is the most used nitrogen fertilizer worldwide, little is known on the capacity of crop plants to use urea per se as a nitrogen source for development and growth. To date, the molecular and physiological bases of its transport have been investigated only in a limited number of species. In particular, up to date only one study reported the transcriptomic modulation induced by urea treatment in the model plant Arabidopsis (Mérigout et al., 2008 doi: 10.1104/pp.108.119339). In maize, one of crops using huge amount of urea, only a physiological characterization of uptake and assimilation of the N-source has been conducted. General aim of the present work was the comprehension of the molecular basis of urea uptake and assimilation in maize plants, using a transcriptomic approach. In addition, the work focused on the possible interactions between the two main N-sources, conceivably occurring concomitantly in the soil, urea and nitrate.
Project description:To investigate the effects of organic fertilizer replacing chemical fertilizer on the growth and development of barley (Kunlun-14), a pot experiment was conducted. The study examined the impacts of different ratios of organic fertilizer replacing chemical fertilizer nitrogen (0%, 40%, 100%, denoted as OFR0, OFR40, OFR100, respectively) on the growth characteristics, leaf carbon-nitrogen balance, and nitrogen metabolism enzyme activities of barley.
Project description:Although urea is the most used nitrogen fertilizer worldwide, little is known on the capacity of crop plants to use urea per se as a nitrogen source for development and growth. To date, the molecular and physiological bases of its transport have been investigated only in a limited number of species. In particular, up to date only one study reported the transcriptomic modulation induced by urea treatment in the model plant Arabidopsis (MM-CM-)rigout et al., 2008 doi: 10.1104/pp.108.119339). In maize, one of crops using huge amount of urea, only a physiological characterization of uptake and assimilation of the N-source has been conducted. General aim of the present work was the comprehension of the molecular basis of urea uptake and assimilation in maize plants, using a transcriptomic approach. In addition, the work focused on the possible interactions between the two main N-sources, conceivably occurring concomitantly in the soil, urea and nitrate. 5 dd-old maize plants were treated for 8 hours with nutrient solution containing nitrogen in form of urea; nitrate; urea and nitrate; or not exposed to any form of nitrogen. Three different biological replicates were used for each sample repeating the experiment three times. All samples were obtained pooling roots of six plants.
Project description:ra05-09_urea - urea - What are the transcriptomic plant responses to urea nitrogen supply ? - Columbia Arabidopsis ecotype were grown hydroponically on 0.5 mM NH4NO3 as sole nitrogen source during 35 days under short days. Plants were then placed on 3 nutrient solutions supplemented, either with 1 mM NH4NO3, or with 0.5 mM NH4NO3 + 0.5 mM Urea, or with 1 mM Urea. Root and shoot samples were harvested separately 7 days after these different nitrogen treatments Keywords: treated vs untreated comparison
Project description:The environment plays important role in the interaction between plant hosts and pathogens. The application of chemical fertilizer is a crucial breeding technology to enhance crop yield since last century. As the most abundant fertilizer, nitrogen often increases disease susceptibility for crop plants. The underlying mechanism for nitrogen induced disease susceptibility is elusive. Here we found that nitrogen application activate gibberellin signaling by degradation of SLR1, the repressor protein in gibberellin signaling, which result in simultaneously promoting plant growth and disease susceptibility. SLR1, physically interacts with OsNPR1 and consequently facilitate OsNPR1 mediated defense responses. Transcriptome analysis showed that OsNPR1-SLR1 module plays a vital role in transcriptional reprogramming for both disease resistance and plant growth. Increase of SLR1 protein level in gibberellin deficient rice plants neutralizes disease susceptibility but sacrifice yield enhancement under high nitrogen supply. Mutation in SD1, encoding OsGA2ox2, produced more grains than WT,and maintains disease resistance under high nitrogen supply. Taken together, our work reveals the molecular mechanism underlying nitrogen-induced disease susceptibility, and demonstrates that the application of sd1 rice varieties prevent the tradeoff between disease susceptibility and yield increase under high nitrogen supply.
Project description:Nitrogen is one of the essential elements for plant growth. NH4+ and NO3- are two major forms of absorbing element N for higher plants. In this study we found that the growth of Panax notoginseng is inhibited when only adding ammonium nitrogen fertilizer, and adding nitrate fertilizer can alleviate the toxicity caused by ammonium. We use RNA-seq to identify genes that are related to the alleviated phenotypes after introducing NO3- to Panax notoginseng roots under NH4+ stresses. Twelve RNA-seq profiles in four sample groups, i.e., control, samples treated with NH4+, samples treated with NO3- only, and treated with both NH4+ and NO3- were obtained and analyzed to identify deregulated genes in samples with different treatments. ACLA-3 gene is downregulated in NH4+ treated samples, but is upregulated in samples treated with NO3- and with both NH4+ and NO3-, which is further validated in another set of samples using qRT-PCR. Our results suggest that unbalanced metabolism of nitrogen and nitrogen is the main cause of ammonium poisoning in roots of Panax notoginseng, and NO3- may significantly upregulate the activity of ACLA-3 which subsequently enhances the citrate cycle and many other metabolic pathways in Panax notoginseng root. These potentially increase the integrity of the Panax notoginseng roots. Our results suggest that introducing NO3- fertilizer is an effective means to prevent the occurrence of toxic ammonium in Panax notoginseng root.
Project description:Nitrification, the oxidation of ammonia via nitrite to nitrate, has always been considered to be a two-step process catalysed by chemolithoautotrophic microorganisms oxidizing either ammonia or nitrite. No known nitrifier carries out both steps, although complete nitrification should be energetically advantageous. This functional separation has puzzled microbiologists for a century. Here we report on the discovery and cultivation of a completely nitrifying bacterium from the genus Nitrospira, a globally distributed group of nitrite oxidizers. The genome of this chemolithoautotrophic organism encodes the pathways both for ammonia and nitrite oxidation, which are concomitantly activated during growth by ammonia oxidation to nitrate. Genes affiliated with the phylogenetically distinct ammonia monooxygenase and hydroxylamine dehydrogenase genes of Nitrospira are present in many environments and were retrieved on Nitrospira contigs in new metagenomes from engineered systems. These findings fundamentally change our picture of nitrification and point to completely nitrifying Nitrospira as key components of nitrogen-cycling microbial communities.
Project description:To find out the genotype specific differentially expressed genes in response to N source Two contrasting Indica rice genotypes namely, Nidhi and Panvel 1 were used. Arnon Hoagland medium with either nitrate or urea were used as fertilizer sources. Two N doses, normal (15 mM of N) was used as control while low (1.5mM of N) was used as test.
Project description:Gene expression was investigated in response to nitrogen fertilizer in developing grains of field grown barley (Hordeum vulgare L. cv. Barke) at four different time points: 10, 15, 18 and 25 days after pollination (DAP).
Project description:Quorum sensing (QS) is a widespread process in bacteria used to coordinate gene expression with cell density, diffusion dynamics, and spatial distribution through the production of diffusible chemical signals. To date, most studies on QS have focused on model bacteria that are amenable to genetic manipulation and capable of high growth rates, but many environmentally important bacteria have been overlooked. For example, representatives of proteobacteria that participate in nitrification, the aerobic oxidation of ammonia to nitrate via nitrite, produce QS signals called acyl-homoserine lactones (AHLs). Nitrification emits nitrogen oxide gases (NO, NO2, and N2O), which are potentially hazardous compounds that contribute to global warming. Despite considerable interest in nitrification, the purpose of QS in the physiology/ecology of nitrifying bacteria is poorly understood. Through a quorum quenching approach, we investigated the role of QS in a well-studied AHL-producing nitrite oxidizer, Nitrobacter winogradskyi.We added a recombinant AiiA lactonase to N. winogradskyi cultures to degrade AHLs to prevent their accumulation and to induce a QS-negative phenotype and then used mRNA sequencing (mRNA-Seq) to identify putative QS-controlled genes. Our transcriptome analysis showed that expression of nirK and nirK cluster genes (ncgABC) increased up to 19.9-fold under QS-proficient conditions (minus active lactonase). These data led to us to query if QS influenced nitrogen oxide gas fluxes in N. winogradskyi. Production and consumption of NOx increased and production of N2O decreased under QS-proficient conditions. Quorum quenching transcriptome approaches have broad potential to identify QS-controlled genes and phenotypes in organisms that are not genetically tractable.