Abstract
Three japonica rice varieties with different cooking and eating quality were grown at high temperature in the greenhouse and natural field. Effects of temperature at the grain filling stage on these varieties were investigated in terms of the activities of key enzymes related to starch synthesis and cooking and eating quality of rice grain. The high temperature at the grain filling stage increased protein content, and decreased amylose content and taste meter value of rice; inferior grain quality varieties showed a greater magnitude of the increase or decrease than the superior ones. Reaction of rapid visco analyser profiles to the temperature varied with rice varieties. The activities of adenosine diphosphoglucose pyrophosphorylase (AGPP), soluble starch synthase (SSS) and starch branching enzyme (SBE) gradually increased to a peak value, and thereafter declined as grain filling progressed. Enzyme activities in different varieties differed in a same filling stage, and also in the time when the enzyme activity reached a maximum. AGPP and SSS were insensitive to the environmental temperature, but SBE was comparatively sensitive to the temperature, and its activity declined when temperature was too high or too low. Rice grain is consumed mostly as cooked rice, and thus cooking and eating properties of rice grain are important quality traits. Amylose content (AC), starch rapid visco analyser (RVA) properties and taste meter value, which are of much importance in physical-chemical properties when cooking and eating quality is evaluated, are affected by chemical components and physical properties of endosperm in grain, and therefore they have close relationship with cooking and eating quality (1-3) . Since starch occupies 90% or more of brown rice weight, the grain filling is characterized by synthesis and accumulation of starch, which is catalyzed by enzymes. The photosynthetic products synthesized in source organs are transported to grain in the form of sucrose, and then catalyzed by enzymes to synthesize starch. Therefore, the activities of the enzymes related to starch synthesis are closely associated with amylose content, starch RVA properties, taste meter value and other cooking and eating properties. It has been shown that in the photosynthetic or non-photosynthetic organs of higher plants, adenosine diphosphoglucose pyrophos- phorylase (EC 2.7.7.21, AGPP), soluble starch
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Claims 8
Claim · model-written summary
High temperature at the grain filling stage increased rice protein content.
- Taxon
- rice
Oryza sativae1 - Treatment
- high temperature at the grain filling stagee1
- Outcome
- protein contente1
- Direction
- increasede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“The high temperature at the grain filling stage increased protein content, and decreased amylose content and taste meter value of rice”
Claim · model-written summary
High temperature at the grain filling stage decreased rice amylose content and taste meter value.
- Taxon
- riceOryza sativae1
- Treatment
- high temperature at the grain filling stagee1
- Outcome
- amylose content and taste meter valuee1
- Direction
- decreasede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“The high temperature at the grain filling stage increased protein content, and decreased amylose content and taste meter value of rice”
Claim · model-written summary
Inferior grain quality rice varieties showed a greater magnitude of the temperature-induced increase or decrease than superior ones.
- Taxon
- RiceOryza sativat0
- Material
- inferior grain quality varietiese1
- Outcome
- magnitude of the increase or decreasee1
- Direction
- greatere1
- Comparator
- the superior onese1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Rice”
e1“inferior grain quality varieties showed a greater magnitude of the increase or decrease than the superior ones”
Claim · model-written summary
The reaction of rapid visco analyser profiles to temperature varied with rice variety.
- Taxon
- riceOryza sativae1
- Material
- rice varietiese1
- Outcome
- rapid visco analyser profilese1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Reaction of rapid visco analyser profiles to the temperature varied with rice varieties”
Claim · model-written summary
Activities of AGPP, SSS and SBE gradually rose to a peak and then declined as grain filling progressed.
- Taxon
- RiceOryza sativat0
- Organ / stage
- grain fillinge1
- Gene
- adenosine diphosphoglucose pyrophosphorylase (AGPP), soluble starch synthase (SSS) and starch branching enzyme (SBE)e1
- Outcome
- activitiese1
- Direction
- gradually increased to a peak value, and thereafter declinede1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Rice”
e1“The activities of adenosine diphosphoglucose pyrophosphorylase (AGPP), soluble starch synthase (SSS) and starch branching enzyme (SBE) gradually increased to a peak value, and thereafter declined as grain filling progressed”
Claim · model-written summary
Enzyme activities differed among varieties at the same filling stage and in the time at which activity peaked.
- Taxon
- RiceOryza sativat0
- Material
- different varietiese1
- Organ / stage
- filling stagee1
- Outcome
- Enzyme activitiese1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Rice”
e1“Enzyme activities in different varieties differed in a same filling stage, and also in the time when the enzyme activity reached a maximum”
Claim · model-written summary
AGPP and SSS activities were insensitive to environmental temperature.
- Taxon
- RiceOryza sativat0
- Treatment
- environmental temperaturee1
- Gene
- AGPP and SSSe1
- Outcome
- insensitivee1
- Direction
- insensitivee1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Rice”
e1“AGPP and SSS were insensitive to the environmental temperature”
Claim · model-written summary
SBE was comparatively sensitive to temperature and its activity declined when temperature was too high or too low.
- Taxon
- RiceOryza sativat0
- Treatment
- temperature was too high or too lowe1
- Gene
- SBEe1
- Outcome
- activitye1
- Direction
- declinede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Rice”
e1“SBE was comparatively sensitive to the temperature, and its activity declined when temperature was too high or too low”