Abstract
Nitrogen (N) supplementation is essential to the yield and quality of bread wheat ( Triticum aestivum L.). The impact of N-deficiency on wheat at the seedling stage has been previously reported, but the impact of distinct N regimes applied at the seedling stage with continuous application on filling and maturing wheat grains is lesser known, despite the filling stage being critical for final grain yield and flour quality. Here, we compared phenotype characteristics such as grain yield, grain protein and sugar quality, plant growth, leaf photosynthesis of wheat under N-deficient and N-sufficient conditions imposed prior to sowing (120 kg/hm 2 ) and in the jointing stage (120 kg/hm 2 ), and then evaluated the effects of this continued stress through RNA-seq and GC-MS metabolomics profiling of grain at the mid-filling stage. The results showed that except for an increase in grain size and weight, and in the content of total sugar, starch, and fiber in bran fraction and white flour, the other metrics were all decreased under N-deficiency conditions. A total of 761 differentially expressed genes (DEGs) and 77 differentially accumulated metabolites (DAMs) were identified. Under N-deficiency, 51 down-regulated DEGs were involved in the process of impeding chlorophyll synthesis, chloroplast development, light harvesting, and electron transfer functions of photosystem, which resulted in the SPAD and Pn value decreased by 32 and 15.2% compared with N-sufficiency, inhibited photosynthesis. Twenty-four DEGs implicated the inhibition of amino acids synthesis and protein transport, in agreement with a 17–42% reduction in ornithine, cysteine, aspartate, and tyrosine from metabolome, and an 18.6% reduction in grain protein content. However, 14 DEGs were implicated in promoting sugar accumulation in the cell wall and another six DEGs also enhanced cell wall synthesis, which significantly increased fiber content in the endosperm and likely contributed to increasing the thousands-grain weight (TGW). Moreover, RNA-seq profiling suggested that wheat grain can improve the capacity of DNA repair, iron uptake, disease and abiotic stress resistance, and oxidative stress scavenging through increasing the content levels of anthocyanin, flavonoid, GABA, galactose, and glucose under N-deficiency condition. This study identified candidate genes and metabolites related to low N adaption and tolerance that may provide new insights into a comprehensive understanding of the genotype-specific differences in performance under N-deficiency conditions.
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Claims 15
Claim · model-written summary
Nitrogen deficiency increased grain size and weight.
- Taxon
- wheat
Triticum aestivume0 - Treatment
- N-deficiente0
- Outcome
- grain size and weighte1
- Direction
- increasee1
- Comparator
- N-sufficiente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“wheat under N-deficient and N-sufficient conditions”
e1“an increase in grain size and weight”
Claim · model-written summary
Nitrogen deficiency increased total sugar, starch, and fiber content in bran and white flour.
- Taxon
- wheatTriticum aestivume0
- Treatment
- N-deficiente0
- Outcome
- content of total sugar, starch, and fibere1
- Direction
- increasee1
- Comparator
- N-sufficiente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“wheat under N-deficient and N-sufficient conditions”
e1“an increase in grain size and weight, and in the content of total sugar, starch, and fiber in bran fraction and white flour”
Claim · model-written summary
Other measured metrics decreased under nitrogen deficiency.
- Taxon
- wheatTriticum aestivume0
- Treatment
- N-deficiencye1
- Outcome
- the other metricse1
- Direction
- decreasede1
- Comparator
- N-sufficiente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“wheat under N-deficient and N-sufficient conditions”
e1“the other metrics were all decreased under N-deficiency conditions”
Claim · model-written summary
The profiling identified 761 differentially expressed genes.
- Taxon
- WheatTriticum aestivumt0
- Outcome
- differentially expressed genese0
- Value
- 761e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Wheat”
e0“A total of 761 differentially expressed genes (DEGs)”
Claim · model-written summary
The profiling identified 77 differentially accumulated metabolites.
- Taxon
- WheatTriticum aestivumt0
- Outcome
- differentially accumulated metabolitese0
- Value
- 77e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Wheat”
e0“77 differentially accumulated metabolites (DAMs) were identified”
Claim · model-written summary
Nitrogen deficiency decreased SPAD by 32%.
- Taxon
- WheatTriticum aestivumt0
- Treatment
- N-deficiencye1
- Outcome
- SPADe0
- Direction
- decreasede0
- Value
- 32e0
- Comparator
- N-sufficiencye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Wheat”
e0“the SPAD and Pn value decreased by 32 and 15.2% compared with N-sufficiency”
e1“the other metrics were all decreased under N-deficiency conditions”
Claim · model-written summary
Nitrogen deficiency decreased Pn by 15.2%.
- Taxon
- WheatTriticum aestivumt0
- Treatment
- N-deficiencye1
- Outcome
- Pne0
- Direction
- decreasede0
- Value
- 15.2%e0
- Comparator
- N-sufficiencye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Wheat”
e0“the SPAD and Pn value decreased by 32 and 15.2% compared with N-sufficiency”
e1“the other metrics were all decreased under N-deficiency conditions”
Claim · model-written summary
Under nitrogen deficiency, 51 downregulated genes were involved in impaired photosystem functions.
- Taxon
- WheatTriticum aestivumt0
- Outcome
- down-regulated DEGse0
- Value
- 51e0
- Qualifier
- chlorophyll synthesis, chloroplast development, light harvesting, and electron transfer functions of photosysteme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Wheat”
e0“Under N-deficiency, 51 down-regulated DEGs were involved in the process of impeding chlorophyll synthesis, chloroplast development, light harvesting, and electron transfer functions of photosystem”
Claim · model-written summary
Amino acid synthesis and protein transport inhibition involved 24 genes.
- Taxon
- WheatTriticum aestivumt0
- Outcome
- DEGse0
- Value
- Twenty-foure0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Wheat”
e0“Twenty-four DEGs implicated the inhibition of amino acids synthesis and protein transport”
Claim · model-written summary
Ornithine, cysteine, aspartate and tyrosine were reduced by 17–42%.
- Taxon
- WheatTriticum aestivumt0
- Treatment
- N-deficiencye1
- Outcome
- ornithine, cysteine, aspartate, and tyrosinee0
- Direction
- reductione0
- Value
- 17–42%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Wheat”
e0“a 17–42% reduction in ornithine, cysteine, aspartate, and tyrosine”
e1“the other metrics were all decreased under N-deficiency conditions”
Claim · model-written summary
Grain protein content was reduced by 18.6%.
- Taxon
- WheatTriticum aestivumt0
- Treatment
- N-deficiencye1
- Outcome
- grain protein contente0
- Direction
- reductione0
- Value
- 18.6%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Wheat”
e0“an 18.6% reduction in grain protein content”
e1“the other metrics were all decreased under N-deficiency conditions”
Claim · model-written summary
Fourteen genes were implicated in promoting cell-wall sugar accumulation.
- Taxon
- WheatTriticum aestivumt0
- Outcome
- DEGse0
- Value
- 14e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Wheat”
e0“14 DEGs were implicated in promoting sugar accumulation in the cell wall”
Claim · model-written summary
Six genes enhanced cell-wall synthesis.
- Taxon
- WheatTriticum aestivumt0
- Outcome
- DEGse0
- Value
- sixe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Wheat”
e0“another six DEGs also enhanced cell wall synthesis”
Claim · model-written summary
Fiber content in endosperm significantly increased.
- Taxon
- WheatTriticum aestivumt0
- Organ / stage
- endosperme0
- Treatment
- N-deficiencye1
- Outcome
- fiber contente0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Wheat”
e0“significantly increased fiber content in the endosperm”
e1“the other metrics were all decreased under N-deficiency conditions”
Claim · model-written summary
Wheat grain may improve stress-related capacities through increased metabolites under nitrogen deficiency.
- Taxon
- wheatTriticum aestivume0
- Compound
- anthocyanin, flavonoid, GABA, galactose, and glucosee0
- Outcome
- capacity of DNA repair, iron uptake, disease and abiotic stress resistance, and oxidative stress scavenginge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“wheat grain can improve the capacity of DNA repair, iron uptake, disease and abiotic stress resistance, and oxidative stress scavenging through increasing the content levels of anthocyanin, flavonoid, GABA, galactose, and glucose under N-deficiency condition”
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