Abstract
Elucidating crops’ physiological and molecular mechanisms to adapt to low nitrogen environment and promoting nitrogen transfer from senescent leaves to new leaves is crucial in improving Brassica ’s nitrogen use efficiency (NUE). Glutamine synthetase gene ( GS ) plays a vital role in helping plants reassimilate ammonium released from protein degradation in leaves, and it was the focus of our research on this topic. In this study, we identified high (H141) and low (L65) NUE genotypes of Brassica juncea with different responses to low-nitrogen stress. We found that H141 has a lower nitrate content but higher ammonium and free amino acid contents as well as higher nitrate reductase and GS activities in the shoots. These physiological indicators are responsible for the high NUE of H141. Whole-genome resequencing data revealed that 5,880 genes associated with NUE are polymorphic between H141 and L65. These genes participate in various amino acid, carbohydrate, and energy metabolic pathways. Haplotype analysis revealed two haplotypes for BjuB05.GS1.4 , Hap1 and Hap2, which have multiple single nucleotide polymorphisms or insertions/deletions in the regulatory regions of the 5´ and 3´ untranslated regions and introns. Furthermore, the shoot NUE of Hap1 is significantly lower than that of Hap2. These two haplotypes of BjuB05.GS1.4 lead to differences in the shoot NUEs of different genetic populations of mustard and are associated with the local soil nitrogen content, suggesting that they might help mustard to adapt to different geographic localities. In conclusion, the results of our study shed light on the physiological and molecular mechanisms underlying different mustard NUE genotypes and demonstrate the enormous potential of NUE breeding in B . juncea .
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Claims 10
Claim · model-written summary
Genotype H141 has a lower shoot nitrate content than L65 under low nitrogen.
- Taxon
- Brassica juncea
Brassica junceat0 - Material
- H141e0
- Outcome
- nitrate contente0
- Direction
- lowere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in Brassica juncea”
e0“We found that H141 has a lower nitrate content”
Claim · model-written summary
Genotype H141 has higher shoot ammonium and free amino acid contents.
- Taxon
- Brassica junceaBrassica junceat0
- Material
- H141e0
- Organ / stage
- shootse1
- Outcome
- ammonium and free amino acid contentse1
- Direction
- highere1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in Brassica juncea”
e0“We found that H141 has a lower nitrate content”
e1“higher ammonium and free amino acid contents as well as higher nitrate reductase and GS activities in the shoots”
Claim · model-written summary
Genotype H141 has higher shoot nitrate reductase and GS activities.
- Taxon
- Brassica junceaBrassica junceat0
- Material
- H141e0
- Organ / stage
- shootse1
- Outcome
- nitrate reductase and GS activitiese1
- Direction
- highere1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in Brassica juncea”
e0“We found that H141 has a lower nitrate content”
e1“higher ammonium and free amino acid contents as well as higher nitrate reductase and GS activities in the shoots”
Claim · model-written summary
The physiological indicators are responsible for the high NUE of H141.
- Taxon
- Brassica junceaBrassica junceat0
- Material
- H141e2
- Outcome
- NUEe2
- Qualifier
- physiological indicatorse2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in Brassica juncea”
e2“These physiological indicators are responsible for the high NUE of H141”
Claim · model-written summary
Whole-genome resequencing found 5,880 NUE-associated genes polymorphic between H141 and L65.
- Taxon
- Brassica junceaBrassica junceat0
- Material
- H141 and L65e3
- Outcome
- genes associated with NUEe3
- Value
- 5,880 genese3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in Brassica juncea”
e3“Whole-genome resequencing data revealed that 5,880 genes associated with NUE are polymorphic between H141 and L65”
Claim · model-written summary
BjuB05.GS1.4 has two haplotypes, Hap1 and Hap2.
- Taxon
- Brassica junceaBrassica junceat0
- Gene
- BjuB05.GS1.4e4
- Outcome
- haplotypese4
- Value
- two haplotypese4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in Brassica juncea”
e4“Haplotype analysis revealed two haplotypes for BjuB05.GS1.4 , Hap1 and Hap2”
Claim · model-written summary
Shoot NUE of Hap1 is significantly lower than that of Hap2.
- Taxon
- Brassica junceaBrassica junceat0
- Material
- Hap1e5
- Organ / stage
- shoote5
- Gene
- BjuB05.GS1.4e4
- Outcome
- shoot NUEe5
- Direction
- lowere5
- Comparator
- Hap2e5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in Brassica juncea”
e4“Haplotype analysis revealed two haplotypes for BjuB05.GS1.4 , Hap1 and Hap2”
e5“Furthermore, the shoot NUE of Hap1 is significantly lower than that of Hap2”
Claim · model-written summary
BjuB05.GS1.4 haplotypes are associated with local soil nitrogen content in mustard populations.
Verbatim
e6“These two haplotypes of BjuB05.GS1.4 lead to differences in the shoot NUEs of different genetic populations of mustard and are associated with the local soil nitrogen content”
Claim · model-written summary
Shoot NUE differs between genetic populations of mustard according to BjuB05.GS1.4 haplotype.
Verbatim
e6“These two haplotypes of BjuB05.GS1.4 lead to differences in the shoot NUEs of different genetic populations of mustard and are associated with the local soil nitrogen content”
Claim · model-written summary
BjuB05.GS1.4 haplotypes might help mustard adapt to different geographic localities.
Verbatim
e6“These two haplotypes of BjuB05.GS1.4 lead to differences in the shoot NUEs of different genetic populations of mustard and are associated with the local soil nitrogen content”
e7“suggesting that they might help mustard to adapt to different geographic localities”