Abstract
More than 4 billion inhabitants in Asia depend on rice for 35-60% of the calories consumed in their diets, but new rice cultivars frequently do not reach expected yields because of poor rice grain filling. Here, we quantified the activities of enzymes involved in starch metabolization in rice to investigate the mechanisms regulating the accumulation and translocation of stem non-structural carbohydrates (NSC) under different levels of nitrogen fertilizer application. A pot experiment was conducted using two rice cultivars, Liangyoupeijiu (LYPJ) and Shanyou63 (SY63), under high and low nitrogen applications. Compared with high nitrogen application (HN), low nitrogen application (LN) increased stem NSC concentration before the heading stage and NSC translocation during the grain filling stage; concomitantly, LN significantly shortened the active grain filling period and increased the grain filling rate in superior spikelets. Compared with the LYPJ cultivar, SY63 exhibited a higher grain weight, higher grain filling percentage, and higher stem NSC concentration before heading and greater NSC translocation after heading. During the period between panicle initiation and heading, the activities of adenosine diphosphate-glucose pyrophosphorylase (AGP), starch synthase (StS), and starch branching enzyme (SBE), all enzymes involved in starch synthesis, increased under the LN treatment and positively correlated with increases in stem NSC. During grain filling, the activities of enzymes involved in starch-to-sucrose conversion [α-amylase, β-amylase, and sucrose phosphate synthase (SPS)] increased under the LN treatment and positively correlated with stem NSC remobilization. Overall, the investigated enzymes exhibited higher activities in SY63 than in LYPJ. Our results suggest that low nitrogen increases the activities of AGP, StS, SBE, α-amylase, β-amylase, and SPS, leading to increased accumulation and remobilization of stem starch and NSC in SY63. We conclude that calculated reductions in nitrogen application and the choice of an appropriate cultivar may improve rice grain yields via enhanced stem NSC accumulation and translocation, thereby reducing the costs and increasing the sustainability of rice production.
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Claims 15
Claim · model-written summary
Low nitrogen increased stem NSC concentration before heading compared with high nitrogen.
- Taxon
- Rice
Oryza sativat0 - Organ / stage
- before the heading stagee0
- Treatment
- low nitrogen application (LN)e0
- Outcome
- stem NSC concentratione0
- Direction
- increasede0
- Comparator
- high nitrogen application (HN)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Rice Stems”
e0“Compared with high nitrogen application (HN), low nitrogen application (LN) increased stem NSC concentration before the heading stage”
Claim · model-written summary
Low nitrogen increased NSC translocation during grain filling.
- Taxon
- RiceOryza sativat0
- Organ / stage
- grain filling stagee0
- Treatment
- low nitrogen application (LN)e0
- Outcome
- NSC translocatione0
- Direction
- increasede0
- Comparator
- high nitrogen application (HN)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Rice Stems”
e0“Compared with high nitrogen application (HN), low nitrogen application (LN) increased stem NSC concentration before the heading stage and NSC translocation during the grain filling stage”
Claim · model-written summary
Low nitrogen significantly shortened the active grain-filling period.
- Taxon
- RiceOryza sativat0
- Treatment
- LNe0
- Outcome
- active grain filling periode0
- Direction
- shortenede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Rice Stems”
e0“LN significantly shortened the active grain filling period”
Claim · model-written summary
Low nitrogen increased grain-filling rate in superior spikelets.
- Taxon
- RiceOryza sativat0
- Organ / stage
- superior spikeletse0
- Treatment
- LNe0
- Outcome
- grain filling ratee0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Rice Stems”
e0“LN significantly shortened the active grain filling period and increased the grain filling rate in superior spikelets”
Claim · model-written summary
SY63 had higher grain weight than LYPJ.
- Taxon
- RiceOryza sativat0
- Material
- SY63e0
- Outcome
- grain weighte0
- Direction
- highere0
- Comparator
- LYPJ cultivare0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Rice Stems”
e0“Compared with the LYPJ cultivar, SY63 exhibited a higher grain weight”
Claim · model-written summary
SY63 had higher grain-filling percentage than LYPJ.
- Taxon
- RiceOryza sativat0
- Material
- SY63e0
- Outcome
- grain filling percentagee0
- Direction
- highere0
- Comparator
- LYPJ cultivare0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Rice Stems”
e0“Compared with the LYPJ cultivar, SY63 exhibited a higher grain weight, higher grain filling percentage”
Claim · model-written summary
SY63 had higher stem NSC before heading than LYPJ.
- Taxon
- RiceOryza sativat0
- Material
- SY63e0
- Organ / stage
- before headinge0
- Outcome
- stem NSC concentratione0
- Direction
- highere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Rice Stems”
e0“SY63 exhibited a higher grain weight, higher grain filling percentage, and higher stem NSC concentration before heading”
Claim · model-written summary
SY63 had greater NSC translocation after heading than LYPJ.
- Taxon
- RiceOryza sativat0
- Organ / stage
- after headinge0
- Outcome
- NSC translocatione0
- Direction
- greatere0
Not reportedMaterial
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Rice Stems”
e0“greater NSC translocation after heading”
Claim · model-written summary
Low nitrogen increased AGP, StS and SBE activity between panicle initiation and heading.
- Taxon
- RiceOryza sativat0
- Organ / stage
- between panicle initiation and headinge0
- Treatment
- LN treatmente0
- Gene
- adenosine diphosphate-glucose pyrophosphorylase (AGP), starch synthase (StS), and starch branching enzyme (SBE)e0
- Outcome
- activitiese0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Rice Stems”
e0“During the period between panicle initiation and heading, the activities of adenosine diphosphate-glucose pyrophosphorylase (AGP), starch synthase (StS), and starch branching enzyme (SBE), all enzymes involved in starch synthesis, increased under the LN treatment”
Claim · model-written summary
Starch-synthesis enzyme activities positively correlated with stem NSC increases.
- Taxon
- RiceOryza sativat0
- Treatment
- LN treatmente0
- Outcome
- stem NSCe0
- Direction
- increasese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Rice Stems”
e0“increased under the LN treatment and positively correlated with increases in stem NSC”
Claim · model-written summary
Low nitrogen increased α-amylase, β-amylase and SPS activities during grain filling.
- Taxon
- RiceOryza sativat0
- Organ / stage
- grain fillinge0
- Treatment
- LN treatmente0
- Gene
- α-amylase, β-amylase, and sucrose phosphate synthase (SPS)e0
- Outcome
- activitiese0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Rice Stems”
e0“During grain filling, the activities of enzymes involved in starch-to-sucrose conversion [α-amylase, β-amylase, and sucrose phosphate synthase (SPS)] increased under the LN treatment”
Claim · model-written summary
Starch-to-sucrose enzyme activities positively correlated with stem NSC remobilization.
- Taxon
- RiceOryza sativat0
- Organ / stage
- steme0
- Outcome
- stem NSC remobilizatione0
- Direction
- positively correlatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Rice Stems”
e0“positively correlated with stem NSC remobilization”
Claim · model-written summary
Investigated enzyme activities were higher in SY63 than LYPJ.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Rice Stems”
e0“Overall, the investigated enzymes exhibited higher activities in SY63 than in LYPJ”
Claim · model-written summary
The authors suggest low nitrogen increases enzyme activities, causing greater starch and NSC accumulation and remobilization in SY63.
- Taxon
- RiceOryza sativat0
- Material
- SY63e0
- Treatment
- low nitrogene0
- Gene
- AGP, StS, SBE, α-amylase, β-amylase, and SPSe0
- Outcome
- accumulation and remobilization of stem starch and NSCe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Rice Stems”
e0“low nitrogen increases the activities of AGP, StS, SBE, α-amylase, β-amylase, and SPS, leading to increased accumulation and remobilization of stem starch and NSC in SY63”
Claim · model-written summary
The authors recommend reducing nitrogen and choosing an appropriate cultivar to improve rice grain yield and sustainability.
- Taxon
- RiceOryza sativat0
- Treatment
- calculated reductions in nitrogen application and the choice of an appropriate cultivare0
- Outcome
- rice grain yieldse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Rice Stems”
e0“calculated reductions in nitrogen application and the choice of an appropriate cultivar may improve rice grain yields via enhanced stem NSC accumulation and translocation, thereby reducing the costs and increasing the sustainability of rice production”
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