Abstract
Abstract Nitrogen (N) is one of the essential factors influencing amino acid synthesis in rice ( Oryza sativa L.) grains. Polyamines (PAs) and ethylene (ETH) play vital roles in grain amino acid biosynthesis of rice. However, knowledge is limited about whether and how PAs and ETH mediate the effect of N rate on amino acid biosynthesis. Two rice cultivars were used with three N rates of low (LN), medium (MN), and high (HN) in the study. Levels of free PAs and ETH, activities/gene expressions of key enzymes related to amino acid synthesis in grains, and the amino acid contents in milled rice were investigated. Free spermidine (Spd) and spermine (Spm) concentrations, especially ratios of free PAs to 1‐aminocylopropane‐1‐carboxylic acid (ACC), and total amino acids (TAAs), essential amino acids (EAAs), and non‐essential amino acids (NEAAs) contents were increased with N rate, while ethylene evolution rate (EER) and ACC concentration were reduced with N increases. There was relatively little difference in the above parameters between MN and HN. Levels of free Spd and Spm, and their ratios to ACC exhibited significant and positive correlations with the activities/gene expressions of key enzymes related to amino acid biosynthesis, and TAAs, NEAAs, and EAAs contents, whereas ACC and EER levels had significantly negative correlations with those parameters. Exogenous Spd, Spm, or AVG (an ETH synthesis inhibitor) increased the enzymatic activities and gene expressions, whereas MGBG (a Spd or Spm synthesis inhibitor) or ethephon (an ETH‐releasing agent) exerted the opposite effect. These results demonstrated that free PAs and ETH antagonistically interact in mediating the effect of N rate on grain amino acid synthesis of rice. Higher ratios of free PAs to ACC could promote synthesis of amino acids in grains of rice.
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Claims 11
Claim · model-written summary
Free spermidine and spermine concentrations in rice grains increased with N rate.
- Taxon
- rice
Oryza sativat0 - Treatment
- N ratee2
- Outcome
- Free spermidine (Spd) and spermine (Spm) concentrationse1
- Direction
- increasede2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Free spermidine (Spd) and spermine (Spm) concentrations”
e2“were increased with N rate”
t0“synthesis of amino acids in rice grains”
Claim · model-written summary
Ratios of free polyamines to ACC in rice grains increased with N rate.
- Taxon
- riceOryza sativat0
- Treatment
- N ratee2
- Outcome
- ratios of free PAs to 1‐aminocylopropane‐1‐carboxylic acid (ACC)e3
- Direction
- increasede2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e3“especially ratios of free PAs to 1‐aminocylopropane‐1‐carboxylic acid (ACC)”
e2“were increased with N rate”
t0“synthesis of amino acids in rice grains”
Claim · model-written summary
Total, essential and non-essential amino acid contents in rice grains increased with N rate.
- Taxon
- riceOryza sativat0
- Treatment
- N ratee2
- Outcome
- total amino acids (TAAs), essential amino acids (EAAs)e3
- Direction
- increasede2
- Qualifier
- amino acids (NEAAs) contentse4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“were increased with N rate”
e3“total amino acids (TAAs), essential amino acids (EAAs)”
e4“amino acids (NEAAs) contents were increased with N rate”
t0“synthesis of amino acids in rice grains”
Claim · model-written summary
Ethylene evolution rate and ACC concentration in rice grains were reduced with N increases.
- Taxon
- riceOryza sativat0
- Treatment
- N increasese5
- Outcome
- ethylene evolution rate (EER) and ACC concentratione5
- Direction
- reducede5
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e5“while ethylene evolution rate (EER) and ACC concentration were reduced with N increases”
t0“synthesis of amino acids in rice grains”
Claim · model-written summary
Medium and high N rates gave relatively little difference in the polyamine, ethylene and amino acid parameters.
- Taxon
- riceOryza sativat0
- Treatment
- HNe6
- Outcome
- the above parameterse6
- Direction
- relatively little differencee6
- Comparator
- MNe6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e6“There was relatively little difference in the above parameters between MN and HN”
t0“synthesis of amino acids in rice grains”
Claim · model-written summary
Levels of free Spd and Spm correlate positively with the activities and gene expressions of key amino acid biosynthesis enzymes in rice grains.
- Taxon
- riceOryza sativat0
- Compound
- free Spd and Spme7
- Outcome
- activities/gene expressions of key enzymes related to amino acid biosynthesise7
- Direction
- significant and positive correlationse7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e7“Levels of free Spd and Spm, and their ratios to ACC exhibited significant and positive correlations with the activities/gene expressions of key enzymes related to amino acid biosynthesis”
t0“synthesis of amino acids in rice grains”
Claim · model-written summary
ACC and ethylene evolution rate correlate negatively with amino acid synthesis parameters in rice grains.
- Taxon
- riceOryza sativat0
- Compound
- ACCe2
- Outcome
- those parameterse2
- Direction
- significantly negative correlationse2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“whereas ACC and EER levels had significantly negative correlations with those parameters”
t0“synthesis of amino acids in rice grains”
Claim · model-written summary
Exogenous spermidine, spermine or AVG increased enzymatic activities and gene expressions in rice grains.
- Taxon
- riceOryza sativat0
- Treatment
- Exogenous Spd, Spm, or AVGe2
- Outcome
- enzymatic activities and gene expressionse2
- Direction
- increasede2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“Exogenous Spd, Spm, or AVG (an ETH synthesis inhibitor) increased the enzymatic activities and gene expressions”
t0“synthesis of amino acids in rice grains”
Claim · model-written summary
MGBG or ethephon had the opposite effect on enzymatic activities and gene expressions in rice grains.
- Taxon
- riceOryza sativat0
- Treatment
- MGBG (a Spd or Spm synthesis inhibitor) or ethephone3
- Outcome
- enzymatic activities and gene expressionse2
- Direction
- opposite effecte4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“Exogenous Spd, Spm, or AVG (an ETH synthesis inhibitor) increased the enzymatic activities and gene expressions”
e3“MGBG (a Spd or Spm synthesis inhibitor) or ethephon”
e4“exerted the opposite effect”
t0“synthesis of amino acids in rice grains”
Claim · model-written summary
Free polyamines and ethylene antagonistically interact in mediating the effect of N rate on grain amino acid synthesis of rice.
- Taxon
- riceOryza sativae2
- Compound
- free PAse2
- Outcome
- grain amino acid synthesise2
- Qualifier
- free PAs and ETH antagonistically interacte2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“free PAs and ETH antagonistically interact in mediating the effect of N rate on grain amino acid synthesis of rice”
t0“synthesis of amino acids in rice grains”
Claim · model-written summary
Higher ratios of free polyamines to ACC could promote amino acid synthesis in rice grains.
- Taxon
- riceOryza sativae2
- Treatment
- Higher ratios of free PAs to ACCe2
- Outcome
- synthesis of amino acids in grainse2
- Direction
- promotee2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“Higher ratios of free PAs to ACC could promote synthesis of amino acids in grains of rice”
t0“synthesis of amino acids in rice grains”
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