Abstract
【Objective】Grain filling in rice is a physiological process of transportation and conversion of photosynthetic assimilates into starch which determines the percentage of filled grains, grain weight, and rice quality. The process of grain filling could not only be affected by genetic factors, but also be regulated by environmental conditions such as temperature and moisture. Irrigation is an important technique in rice production and plays a vital role in regulating the formation of grain yield. However, little work has been done in the effect of postanthesis irrigation patterns on the expressions of genes encoding starch biosynthesis in rice grains. This study aims to investigate the effect of post-anthesis alternate wetting and drying irrigation on grain filling of rice and to understand its molecular mechanism.【Method】Two cultivars Liangyoupeijiu(two-line indica hybrids) and Yangjing 4038(japonica hybrids) were used and grown in the cement tanks that were filled with soil. Three irrigation regimes were imposed from heading(50% of the panicles were protrudent the flag leaf sheath) to maturity:(1) conventional irrigation(CI), plots were kept a continuous shallow water layer until one week before harvest;(2) alternate wetting and moderate soil drying irrigation(WMD), the field was not irrigated until the soil water potential reached the threshold at-20 k Pa, and then was flooded with 1-2 cm water depth, and was repeated this process again;(3) alternate wetting and severe soil drying irrigation(WSD), water in the plots was withheld until the soil water potential reached the threshold at-40 k Pa, and then was flooded with 1-2 cm water depth, and this process was repeated again. The effect of irrigation regimes on grain filling rate, grain weight, activities of the enzymes involved in starch synthesis in superior and inferior spikelets, and expressions of the genes encoding these enzymes were determined using real-time quantitative PCR.【Result】The results showed that there were no significant differences in grain filling rate, grain weight, activities of enzymes involved in starch synthesis including sucrose synthase(Su S), adenosine diphosphate glucose pyrophosphorylase(AGP), starch synthase(St S), starch branching enzyme(SBE) and Su S2, Su S4, AGPL1, AGPL2, AGPL3, AGPS2, SSI, SSIIa, SSIIc, SSIIIa, SBEI and SBEIIb gene expressions in superior spikelets among the three irrigation treatments. Compared with CI, the WMD significantly increased the mean grain filling rate, grain weight, activities of the four enzymes involved in starch synthesis and their gene expressions in inferior spikelets except for AGPL1, whereas the WSD performed an opposite effect. The two trial cultivars behaved the same tendency. The correlation analysis showed that the mean grain filling rate and the grain weight of inferior spikelets were very significantly and positively correlated with activities of Su S, AGP, St S, SBE and gene expressions of Su S2, Su S4, AGPL2, AGPL3, AGPS2, SSI, SSIIa, SSIIc, SSIIIa, SBEI and SBEIIb. 【Conclusion】The results indicate that enhanced activities and gene expressions of the enzymes involved in starch synthesis in inferior spikelets under WMD contribute to their greater grain filling rate and grain weight through enhancing the starch synthesis and accumulation. The reduction in the grain filling rate and grain weight of inferior spikelets under WSD would be attributed to the decreased activities and gene expressions of the enzymes involved in starch synthesis.
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Claims 11
Claim · model-written summary
Superior spikelets showed no significant differences among irrigation regimes in grain filling rate and grain weight.
- Taxon
- rice
Oryza sativat0 - Organ / stage
- superior spikeletse0
- Treatment
- three irrigation treatmentse0
- Outcome
- grain filling rate, grain weighte0
- Direction
- no significant differencese0
- Comparator
- three irrigation treatmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“there were no significant differences in grain filling rate, grain weight, activities of enzymes involved in starch synthesis including sucrose synthase(Su S), adenosine diphosphate glucose pyrophosphorylase(AGP), starch synthase(St S), starch branching enzyme(SBE) and Su S2, Su S4, AGPL1, AGPL2, AGPL3, AGPS2, SSI, SSIIa, SSIIc, SSIIIa, SBEI and SBEIIb gene expressions in superior spikelets among the three irrigation treatments”
t0“Rice Grains”
Claim · model-written summary
Superior spikelets showed no significant differences in starch-synthesis enzyme activities among irrigation regimes.
- Taxon
- RiceOryza sativat0
- Organ / stage
- superior spikeletse0
- Treatment
- three irrigation treatmentse0
- Outcome
- activities of enzymes involved in starch synthesise0
- Direction
- no significant differencese0
- Comparator
- three irrigation treatmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“there were no significant differences in grain filling rate, grain weight, activities of enzymes involved in starch synthesis including sucrose synthase(Su S), adenosine diphosphate glucose pyrophosphorylase(AGP), starch synthase(St S), starch branching enzyme(SBE) and Su S2, Su S4, AGPL1, AGPL2, AGPL3, AGPS2, SSI, SSIIa, SSIIc, SSIIIa, SBEI and SBEIIb gene expressions in superior spikelets among the three irrigation treatments”
t0“Rice Grains”
Claim · model-written summary
Superior spikelets showed no significant differences in starch-synthesis gene expressions among irrigation regimes.
- Taxon
- RiceOryza sativat0
- Organ / stage
- superior spikeletse0
- Treatment
- three irrigation treatmentse0
- Outcome
- gene expressionse0
- Direction
- no significant differencese0
- Comparator
- three irrigation treatmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“there were no significant differences in grain filling rate, grain weight, activities of enzymes involved in starch synthesis including sucrose synthase(Su S), adenosine diphosphate glucose pyrophosphorylase(AGP), starch synthase(St S), starch branching enzyme(SBE) and Su S2, Su S4, AGPL1, AGPL2, AGPL3, AGPS2, SSI, SSIIa, SSIIc, SSIIIa, SBEI and SBEIIb gene expressions in superior spikelets among the three irrigation treatments”
t0“Rice Grains”
Claim · model-written summary
Moderate drying significantly increased mean grain filling rate in inferior spikelets relative to CI.
- Taxon
- RiceOryza sativat0
- Organ / stage
- inferior spikeletse0
- Treatment
- WMDe0
- Outcome
- mean grain filling ratee0
- Direction
- increasede0
- Comparator
- CIe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Compared with CI, the WMD significantly increased the mean grain filling rate, grain weight, activities of the four enzymes involved in starch synthesis and their gene expressions in inferior spikelets except for AGPL1”
t0“Rice Grains”
Claim · model-written summary
Moderate drying significantly increased grain weight in inferior spikelets relative to CI.
- Taxon
- RiceOryza sativat0
- Organ / stage
- inferior spikeletse0
- Treatment
- WMDe0
- Outcome
- grain weighte0
- Direction
- increasede0
- Comparator
- CIe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Compared with CI, the WMD significantly increased the mean grain filling rate, grain weight, activities of the four enzymes involved in starch synthesis and their gene expressions in inferior spikelets except for AGPL1”
t0“Rice Grains”
Claim · model-written summary
Moderate drying significantly increased starch-synthesis enzyme activities in inferior spikelets relative to CI.
- Taxon
- RiceOryza sativat0
- Organ / stage
- inferior spikeletse0
- Treatment
- WMDe0
- Outcome
- activities of the four enzymes involved in starch synthesise0
- Direction
- increasede0
- Comparator
- CIe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Compared with CI, the WMD significantly increased the mean grain filling rate, grain weight, activities of the four enzymes involved in starch synthesis and their gene expressions in inferior spikelets except for AGPL1”
t0“Rice Grains”
Claim · model-written summary
Moderate drying significantly increased starch-synthesis gene expressions except AGPL1 in inferior spikelets.
- Taxon
- RiceOryza sativat0
- Organ / stage
- inferior spikeletse0
- Treatment
- WMDe0
- Outcome
- gene expressionse0
- Direction
- increasede0
- Qualifier
- except for AGPL1e0
- Comparator
- CIe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Compared with CI, the WMD significantly increased the mean grain filling rate, grain weight, activities of the four enzymes involved in starch synthesis and their gene expressions in inferior spikelets except for AGPL1”
t0“Rice Grains”
Claim · model-written summary
Severe drying had the opposite effect to moderate drying on inferior spikelet grain filling, grain weight, enzyme activity and gene expression.
- Taxon
- RiceOryza sativat0
- Treatment
- WSDe0
- Outcome
- mean grain filling rate, grain weight, activities of the four enzymes involved in starch synthesis and their gene expressionse1
- Direction
- opposite effecte0
- Comparator
- CIe1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“whereas the WSD performed an opposite effect”
t0“Rice Grains”
e1“Compared with CI, the WMD significantly increased the mean grain filling rate, grain weight, activities of the four enzymes involved in starch synthesis and their gene expressions in inferior spikelets except for AGPL1”
Claim · model-written summary
Both rice cultivars showed the same tendency.
- Taxon
- RiceOryza sativat0
- Outcome
- same tendencye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The two trial cultivars behaved the same tendency”
t0“Rice Grains”
Claim · model-written summary
Inferior spikelet grain filling rate correlated positively with starch-synthesis enzyme activities and gene expressions.
- Taxon
- RiceOryza sativat0
- Organ / stage
- inferior spikeletse0
- Gene
- Su S2, Su S4, AGPL2, AGPL3, AGPS2, SSI, SSIIa, SSIIc, SSIIIa, SBEI and SBEIIbe0
- Outcome
- mean grain filling ratee0
- Direction
- positively correlatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the mean grain filling rate and the grain weight of inferior spikelets were very significantly and positively correlated with activities of Su S, AGP, St S, SBE and gene expressions of Su S2, Su S4, AGPL2, AGPL3, AGPS2, SSI, SSIIa, SSIIc, SSIIIa, SBEI and SBEIIb”
t0“Rice Grains”
Claim · model-written summary
Inferior spikelet grain weight correlated positively with starch-synthesis enzyme activities and gene expressions.
- Taxon
- RiceOryza sativat0
- Organ / stage
- inferior spikeletse0
- Gene
- Su S2, Su S4, AGPL2, AGPL3, AGPS2, SSI, SSIIa, SSIIc, SSIIIa, SBEI and SBEIIbe0
- Outcome
- grain weighte0
- Direction
- positively correlatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the mean grain filling rate and the grain weight of inferior spikelets were very significantly and positively correlated with activities of Su S, AGP, St S, SBE and gene expressions of Su S2, Su S4, AGPL2, AGPL3, AGPS2, SSI, SSIIa, SSIIc, SSIIIa, SBEI and SBEIIb”
t0“Rice Grains”
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