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Increased biomass accumulation in maize grown in mixed nitrogen supply is mediated by auxin synthesis
- Source :
- Journal of Experimental Botany
- Publication Year :
- 2019
- Publisher :
- Oxford University Press (OUP), 2019.
-
Abstract
- Maize plants grown in the presence of a mixed nitrate and ammonium supply exhibited rapid biomass accumulation associated with increased auxin biosynthesis and up-regulation of auxin-responsive transcripts, including those known to regulate cell expansion.<br />The use of mixed nitrate and ammonium as a nitrogen source can improve plant growth. Here, we used metabolomics and transcriptomics to study the underlying mechanisms. Maize plants were grown hydroponically in the presence of three forms of nitrogen (nitrate alone, 75%/25% nitrate/ammonium, and ammonium alone). Plants grown with mixed nitrogen had a higher photosynthetic rate than those supplied only with nitrate, and had the highest leaf area and shoot and root biomass among the three nitrogen treatments. In shoot and root, the concentration of nitrogenous compounds (ammonium, glutamine, and asparagine) and carbohydrates (sucrose, glucose, and fructose) in plants with a mixed nitrogen supply was higher than that with nitrate supply, but lower than that with ammonium supply. The activity of the related enzymes (glutamate synthase, asparagine synthase, phosphoenolpyruvate carboxylase, invertase, and ADP-glucose pyrophosphorylase) changed accordingly. Specifically, the mixed nitrogen source enhanced auxin synthesis via the shikimic acid pathway, as indicated by the higher levels of phosphoenolpyruvate and tryptophan compared with the other two treatments. The expression of corresponding genes involving auxin synthesis and response was up-regulated. Supply of only ammonium resulted in high levels of glutamine and asparagine, starch, and trehalose hexaphosphate. We conclude that, in addition to increased photosynthesis, mixed nitrogen supply enhances leaf growth via increasing auxin synthesis to build a large sink for carbon and nitrogen utilization, which, in turn, facilitates further carbon assimilation and nitrogen uptake.
- Subjects :
- 0106 biological sciences
0301 basic medicine
leaf area
root growth
Nitrogen
Physiology
chemistry.chemical_element
Plant Science
maize
Photosynthesis
Zea mays
01 natural sciences
03 medical and health sciences
chemistry.chemical_compound
Nitrate
nitrate
Glutamate synthase
heterocyclic compounds
Ammonium
Biomass
Food science
Asparagine
mixed N form
shikimic acid pathway
carbon and nitrogen metabolism
Indoleacetic Acids
biology
fungi
food and beverages
source–sink relationship
Research Papers
030104 developmental biology
chemistry
Asparagine Synthase
biology.protein
auxin
Phosphoenolpyruvate carboxylase
Photosynthesis and Metabolism
010606 plant biology & botany
Subjects
Details
- ISSN :
- 14602431 and 00220957
- Volume :
- 70
- Database :
- OpenAIRE
- Journal :
- Journal of Experimental Botany
- Accession number :
- edsair.doi.dedup.....2af830b80ac43176a2f514b3098f04d9