Abstract
Global warming poses a critical threat to rice production, with elevated daytime temperatures during reproduction causing irreversible yield losses. The premium aromatic cultivar ‘Khao Dawk Mali 105’ (‘KDML105’) is widely cultivated in Thailand but is highly heat-sensitive. To assess its vulnerability, plants were grown under controlled environments at 32, 36, and 40 °C from panicle initiation to maturity. Daytime warming ≥36 °C delayed flowering, shortened culm and panicle length, and inhibited uppermost internode elongation, resulting in incomplete panicle exsertion. Anther development was strongly affected, with reduced size, collapse of structural integrity, and poor pollen release at 36 °C, progressing to deformation and complete sterility at 40 °C. Spikelet fertility declined sharply with rising temperature, culminating in 100% sterility at 40 °C, confirming the narrow thermal threshold of ‘KDML105’. At the molecular level, elevated temperature downregulated proline–GABA pathway genes ( OsP5cs , OsProDH , OsOat , Osbadh2 ), suppressed biosynthesis of 2-acetyl-1-pyrroline (2AP), and increased volatilization losses, thereby diminishing aroma. Together, these results show that long-term elevated daytime temperature simultaneously compromises reproductive success and fragrance quality. Panicle traits and anther morphology serve as sensitive indicators for screening heat tolerance, while targeted breeding and adaptive agronomic strategies are essential to protect yield and grain quality in aromatic rice under future climate scenarios. • Daytime temperature ≥36 °C) during reproduction caused complete sterility in ‘KDML105’ rice. • High temperature reduced anther size, impaired dehiscence, and lowered pollen viability. • Culm elongation and panicle exsertion were suppressed, restricting pollination efficiency. • Elevated temperature downregulated proline–GABA pathway genes, limiting 2AP biosynthesis. • Long-term daytime warming threatens both yield and aroma quality in aromatic rice.
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Claims 11
Claim · model-written summary
Warming at least 36 °C delayed flowering.
- Taxon
- rice
Oryza sativat0 - Material
- KDML105t0
- Treatment
- Daytime warming ≥36 °Ce0
- Outcome
- floweringe0
- Direction
- delayede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Daytime warming ≥36 °C delayed flowering”
e1“Daytime warming ≥36 °C delayed flowering”
t0“rice ‘KDML105’”
Claim · model-written summary
Warming shortened culm and panicle length.
- Taxon
- riceOryza sativat0
- Treatment
- Daytime warming ≥36 °Ce0
- Outcome
- culm and panicle lengthe0
- Direction
- shortenede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Daytime warming ≥36 °C delayed flowering, shortened culm and panicle length”
e1“Daytime warming ≥36 °C delayed flowering, shortened culm and panicle length”
t0“rice”
Claim · model-written summary
Warming inhibited uppermost internode elongation and led to incomplete panicle exsertion.
- Taxon
- riceOryza sativat0
- Treatment
- Daytime warming ≥36 °Ce1
- Outcome
- uppermost internode elongatione0
- Direction
- inhibitede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“inhibited uppermost internode elongation, resulting in incomplete panicle exsertion”
e1“Daytime warming ≥36 °C delayed flowering”
t0“rice”
Claim · model-written summary
At 36 °C, anthers were smaller and structurally collapsed with poor pollen release.
- Taxon
- riceOryza sativat0
- Organ / stage
- Anthere1
- Treatment
- 36 °Ce0
- Outcome
- size, collapse of structural integrity, and poor pollen releasee0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“reduced size, collapse of structural integrity, and poor pollen release at 36 °C”
e1“Anther development was strongly affected”
t0“rice”
Claim · model-written summary
At 40 °C, anthers became deformed and completely sterile.
- Taxon
- riceOryza sativat0
- Treatment
- 40 °Ce0
- Outcome
- deformation and complete sterilitye0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“progressing to deformation and complete sterility at 40 °C”
e1“progressing to deformation and complete sterility at 40 °C”
t0“rice”
Claim · model-written summary
Spikelet fertility declined with rising temperature, reaching 100% sterility at 40 °C.
- Taxon
- riceOryza sativat0
- Treatment
- rising temperaturee0
- Outcome
- Spikelet fertilitye0
- Direction
- declinede0
- Value
- 100% sterilitye0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Spikelet fertility declined sharply with rising temperature, culminating in 100% sterility at 40 °C”
e1“Spikelet fertility declined sharply with rising temperature, culminating in 100% sterility at 40 °C”
t0“rice”
Claim · model-written summary
Elevated temperature downregulated four proline–GABA pathway genes.
- Taxon
- riceOryza sativat0
- Treatment
- elevated temperaturee0
- Gene
- OsP5cs , OsProDH , OsOat , Osbadh2e0
- Outcome
- proline–GABA pathway genese0
- Direction
- downregulatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“elevated temperature downregulated proline–GABA pathway genes ( OsP5cs , OsProDH , OsOat , Osbadh2 )”
e1“elevated temperature downregulated proline–GABA pathway genes ( OsP5cs , OsProDH , OsOat , Osbadh2 )”
t0“rice”
Claim · model-written summary
Elevated temperature suppressed 2AP biosynthesis.
- Taxon
- riceOryza sativat0
- Treatment
- elevated temperaturee1
- Outcome
- biosynthesis of 2-acetyl-1-pyrroline (2AP)e0
- Direction
- suppressede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“suppressed biosynthesis of 2-acetyl-1-pyrroline (2AP)”
e1“elevated temperature downregulated proline–GABA pathway genes ( OsP5cs , OsProDH , OsOat , Osbadh2 )”
t0“rice”
Claim · model-written summary
Elevated temperature increased volatilization losses.
- Taxon
- riceOryza sativat0
- Treatment
- elevated temperaturee1
- Outcome
- volatilization lossese0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased volatilization losses, thereby diminishing aroma”
e1“elevated temperature downregulated proline–GABA pathway genes ( OsP5cs , OsProDH , OsOat , Osbadh2 )”
t0“rice”
Claim · model-written summary
Authors identify panicle traits and anther morphology as indicators for heat tolerance screening.
- Taxon
- riceOryza sativat0
- Outcome
- Panicle traits and anther morphologye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Panicle traits and anther morphology serve as sensitive indicators for screening heat tolerance”
e1“Panicle traits and anther morphology serve as sensitive indicators for screening heat tolerance”
t0“rice”
Claim · model-written summary
Authors recommend targeted breeding and adaptive agronomic strategies.
- Taxon
- riceOryza sativae0
- Outcome
- targeted breeding and adaptive agronomic strategiese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“targeted breeding and adaptive agronomic strategies are essential to protect yield and grain quality in aromatic rice”
e1“targeted breeding and adaptive agronomic strategies are essential to protect yield and grain quality in aromatic rice”
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