Abstract
Excessive nitrogen (N) fertilization is widely used to increase rice yield, but it often leads to lodging by weakening culm strength. This study aimed to elucidate the structural and molecular mechanisms underlying nitrogen-induced changes in culm lodging resistance in rice. Field and pot experiments with two nitrogen levels were conducted using a randomized design with three biological replicates to evaluate the effects of high nitrogen application on culm mechanical properties, secondary cell wall development, and associated metabolic pathways. Mechanical measurements and microscopic analysis revealed that high nitrogen significantly reduced culm rigidity and impaired sclerenchyma development. To investigate the underlying mechanisms, integrated transcriptomic and proteomic analyses were performed on developing internodes. Differentially expressed genes and proteins were predominantly enriched in carbohydrate metabolism and phenylpropanoid biosynthesis pathways. Notably, key enzymes involved in lignin biosynthesis were consistently downregulated at the protein level under high-nitrogen conditions. In contrast, genes and proteins related to cellulose and hemicellulose biosynthesis exhibited transient inhibition at early stages followed by recovery or upregulation at later stages. Consistent with these findings, histochemical staining and quantitative assays demonstrated a significant reduction (14–16%) in lignin content in the fourth internode, whereas cellulose content showed no substantial change. Furthermore, lignin biosynthetic genes (OsCAD2, Os4CL3, and OsCOMT) were persistently suppressed during critical stages of secondary wall formation, while cellulose synthase genes (OsCESA4, OsCESA7, and OsCESA9) displayed more variable and less sustained expression patterns. Collectively, these results demonstrate that excessive nitrogen application weakens rice culms primarily by inhibiting lignin accumulation rather than cellulose deposition. The preferential suppression of the phenylpropanoid pathway and disruption of secondary cell wall formation provide a mechanistic basis for nitrogen-induced lodging susceptibility in rice.
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Claims 11
Claim · model-written summary
High nitrogen significantly reduced culm rigidity in rice.
- Taxon
- rice
Oryza sativae0 - Treatment
- high nitrogene1
- Outcome
- culm rigiditye1
- Direction
- reducede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“changes in culm lodging resistance in rice”
e1“high nitrogen significantly reduced culm rigidity and impaired sclerenchyma development”
Claim · model-written summary
High nitrogen significantly impaired sclerenchyma development in rice culms.
- Taxon
- riceOryza sativae0
- Organ / stage
- sclerenchymae1
- Treatment
- high nitrogene1
- Outcome
- sclerenchyma developmente1
- Direction
- impairede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“changes in culm lodging resistance in rice”
e1“high nitrogen significantly reduced culm rigidity and impaired sclerenchyma development”
Claim · model-written summary
Differentially expressed genes and proteins in developing internodes were predominantly enriched in carbohydrate metabolism and phenylpropanoid biosynthesis pathways.
- Taxon
- riceOryza sativae0
- Organ / stage
- developing internodese4
- Outcome
- carbohydrate metabolism and phenylpropanoid biosynthesis pathwayse3
- Qualifier
- predominantly enrichede3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“changes in culm lodging resistance in rice”
e3“Differentially expressed genes and proteins were predominantly enriched in carbohydrate metabolism and phenylpropanoid biosynthesis pathways”
e4“integrated transcriptomic and proteomic analyses were performed on developing internodes”
Claim · model-written summary
High nitrogen consistently downregulated key lignin biosynthesis enzymes at the protein level.
- Taxon
- riceOryza sativae0
- Treatment
- high-nitrogen conditionse5
- Outcome
- key enzymes involved in lignin biosynthesise5
- Direction
- downregulatede5
- Qualifier
- at the protein levele5
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“changes in culm lodging resistance in rice”
e5“key enzymes involved in lignin biosynthesis were consistently downregulated at the protein level under high-nitrogen conditions”
Claim · model-written summary
Cellulose and hemicellulose biosynthesis genes and proteins showed transient inhibition at early stages.
- Taxon
- riceOryza sativae0
- Organ / stage
- early stagese6
- Outcome
- genes and proteins related to cellulose and hemicellulose biosynthesise6
- Direction
- transient inhibitione6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“changes in culm lodging resistance in rice”
e6“genes and proteins related to cellulose and hemicellulose biosynthesis exhibited transient inhibition at early stages”
Claim · model-written summary
High nitrogen reduced lignin content by 14–16% in the fourth internode of rice.
- Taxon
- riceOryza sativae0
- Organ / stage
- fourth internodee7
- Outcome
- lignin contente7
- Direction
- reductione7
- Value
- 14–16%e7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“changes in culm lodging resistance in rice”
e7“histochemical staining and quantitative assays demonstrated a significant reduction (14–16%) in lignin content in the fourth internode, whereas cellulose content showed no substantial change”
Claim · model-written summary
Cellulose content in the fourth internode of rice showed no substantial change.
- Taxon
- riceOryza sativae0
- Organ / stage
- fourth internodee7
- Outcome
- cellulose contente7
- Direction
- no substantial changee7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“changes in culm lodging resistance in rice”
e7“histochemical staining and quantitative assays demonstrated a significant reduction (14–16%) in lignin content in the fourth internode, whereas cellulose content showed no substantial change”
Claim · model-written summary
Lignin biosynthetic genes OsCAD2, Os4CL3 and OsCOMT were persistently suppressed during critical stages of secondary wall formation in rice.
- Taxon
- riceOryza sativae0
- Organ / stage
- secondary wall formatione1
- Gene
- OsCAD2, Os4CL3, and OsCOMTe1
- Outcome
- lignin biosynthetic genese1
- Direction
- suppressede1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“changes in culm lodging resistance in rice”
e1“lignin biosynthetic genes (OsCAD2, Os4CL3, and OsCOMT) were persistently suppressed during critical stages of secondary wall formation”
Claim · model-written summary
Cellulose synthase genes OsCESA4, OsCESA7 and OsCESA9 showed more variable and less sustained expression in rice.
- Taxon
- riceOryza sativae0
- Gene
- OsCESA4, OsCESA7, and OsCESA9e2
- Outcome
- expression patternse2
- Qualifier
- more variable and less sustainede2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“changes in culm lodging resistance in rice”
e2“cellulose synthase genes (OsCESA4, OsCESA7, and OsCESA9) displayed more variable and less sustained expression patterns”
Claim · model-written summary
Excessive nitrogen weakens rice culms mainly by inhibiting lignin accumulation rather than cellulose deposition.
- Taxon
- riceOryza sativae0
- Treatment
- excessive nitrogen applicatione3
- Outcome
- lignin accumulatione3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“changes in culm lodging resistance in rice”
e3“excessive nitrogen application weakens rice culms primarily by inhibiting lignin accumulation rather than cellulose deposition”
Claim · model-written summary
Suppression of the phenylpropanoid pathway and disruption of secondary cell wall formation provide a mechanistic basis for nitrogen-induced lodging susceptibility in rice.
- Taxon
- riceOryza sativae0
- Outcome
- lodging susceptibilitye4
- Qualifier
- suppression of the phenylpropanoid pathwaye4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“changes in culm lodging resistance in rice”
e4“The preferential suppression of the phenylpropanoid pathway and disruption of secondary cell wall formation provide a mechanistic basis for nitrogen-induced lodging susceptibility in rice”
The same questions in other papers
nitrogen · growth · Oryza sativa (rice)Positive and negative results
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