Dataset Information

Differential contributions of NO3 -/NH4 + to nitrogen use in response to a variable inorganic nitrogen supply in plantlets of two Brassicaceae species in vitro.

ABSTRACT: Background:The primary sources of nitrogen for plants have been suggested to be nitrate (NO3 -) and ammonium (NH4 +). However, when both nitrate and ammonium are simultaneously available to plants, it is very difficult to differentially quantify NO3 -/NH4 + utilization in culture media or soil. Consequently, the contribution of NO3 -/NH4 + to total inorganic nitrogen assimilation cannot be determined. Results:We developed a method called the bidirectional stable nitrogen isotope tracer to differentially quantify the nitrate and ammonium utilization by Orychophragmus violaceus (Ov) and Brassica napus (Bn) plantlets in vitro. The utilization efficiency of nitrate was markedly lower than the utilization efficiency of ammonium for plantlets of both Ov and Bn. In both Ov and Bn, the proportion of NO3 -/NH4 + utilization did not show a linear relationship with inorganic nitrogen supply. The Ov plantlets assimilated more nitrate than the Bn plantlets at the lowest inorganic nitrogen concentration. Conclusions:Quantifying the utilization of nitrate and ammonium can reveal the differences in nitrate and ammonium assimilation among plants at different inorganic nitrogen supply levels and provide an alternate way to conveniently optimize the supply of inorganic nitrogen in culture media.

SUBMITTER: Zhang K

PROVIDER: S-EPMC6668107 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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Differential contributions of NO3 -/NH4 + to nitrogen use in response to a variable inorganic nitrogen supply in plantlets of two Brassicaceae species in vitro.

Zhang Kaiyan K Wu Yanyou Y Hang Hongtao H

Plant methods 20190731

<h4>Background</h4>The primary sources of nitrogen for plants have been suggested to be nitrate (NO3 -) and ammonium (NH4 +). However, when both nitrate and ammonium are simultaneously available to plants, it is very difficult to differentially quantify NO3 -/NH4 + utilization in culture media or soil. Consequently, the contribution of NO3 -/NH4 + to total inorganic ...[more]

PMID: 31384291

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Project description:Wheat growth and nitrogen (N) uptake gradually decrease in response to high NH4 +/NO3 - ratio. However, the mechanisms underlying the response of wheat seedling roots to changes in NH4 +/NO3 - ratio remain unclear. In this study, we investigated wheat growth, transcriptome, and proteome profiles of roots in response to increasing NH4 +/NO3 - ratios (N a : 100/0; N r1: 75/25, N r2: 50/50, N r3: 25/75, and N n : 0/100). High NH4 +/NO3 - ratio significantly reduced leaf relative chlorophyll content, Fv/Fm, and ΦII values. Both total root length and specific root length decreased with increasing NH4 +/NO3 - ratios. Moreover, the rise in NH4 +/NO3 - ratio significantly promoted O2 - production. Furthermore, transcriptome sequencing and tandem mass tag-based quantitative proteome analyses identified 14,376 differentially expressed genes (DEGs) and 1,819 differentially expressed proteins (DEPs). The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis indicated that glutathione metabolism and phenylpropanoid biosynthesis were the main two shared enriched pathways across ratio comparisons. Upregulated DEGs and DEPs involving glutathione S-transferases may contribute to the prevention of oxidative stress. An increment in the NH4 +/NO3 - ratio induced the expression of genes and proteins involved in lignin biosynthesis, which increased root lignin content. Additionally, phylogenetic tree analysis showed that both A0A3B6NPP6 and A0A3B6LM09 belong to the cinnamyl-alcohol dehydrogenase subfamily. Fifteen downregulated DEGs were identified as high-affinity nitrate transporters or nitrate transporters. Upregulated TraesCS3D02G344800 and TraesCS3A02G350800 were involved in ammonium transport. Downregulated A0A3B6Q9B3 is involved in nitrate transport, whereas A0A3B6PQS3 is a ferredoxin-nitrite reductase. This may explain why an increase in the NH4 +/NO3 - ratio significantly reduced root NO3 --N content but increased NH4 +-N content. Overall, these results demonstrated that increasing the NH4 +/NO3 - ratio at the seedling stage induced the accumulation of reactive oxygen species, which in turn enhanced root glutathione metabolism and lignification, thereby resulting in increased root oxidative tolerance at the cost of reducing nitrate transport and utilization, which reduced leaf photosynthetic capacity and, ultimately, plant biomass accumulation.

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Dataset Information

Differential contributions of NO3 -/NH4 + to nitrogen use in response to a variable inorganic nitrogen supply in plantlets of two Brassicaceae species in vitro.

Publications

Differential contributions of NO<sub>3</sub> <sup>-</sup>/NH<sub>4</sub> <sup>+</sup> to nitrogen use in response to a variable inorganic nitrogen supply in plantlets of two Brassicaceae species in vitro.

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