Abstract
Persistent high temperature decreases the yield and quality of crops, including many important herbs. White clover (Trifolium repens) is a perennial herb with high feeding and medicinal value, but is sensitive to temperatures above 30 °C. The present study was conducted to elucidate the impact of changes in endogenous γ-aminobutyric acid (GABA) level by exogenous GABA pretreatment on heat tolerance of white clover, associated with alterations in endogenous hormones, antioxidant metabolism, and aquaporin-related gene expression in root and leaf of white clover plants under high-temperature stress. Our results reveal that improvement in endogenous GABA level in leaf and root by GABA pretreatment could significantly alleviate the damage to white clover during high-temperature stress, as demonstrated by enhancements in cell membrane stability, photosynthetic capacity, and osmotic adjustment ability, as well as lower oxidative damage and chlorophyll loss. The GABA significantly enhanced gene expression and enzyme activities involved in antioxidant defense, including superoxide dismutase, catalase, peroxidase, and key enzymes of the ascorbic acid–glutathione cycle, thus reducing the accumulation of reactive oxygen species and the oxidative injury to membrane lipids and proteins. The GABA also increased endogenous indole-3-acetic acid content in roots and leaves and cytokinin content in leaves, associated with growth maintenance and reduced leaf senescence under heat stress. The GABA significantly upregulated the expression of PIP1-1 and PIP2-7 in leaves and the TIP2-1 expression in leaves and roots under high temperature, and also alleviated the heat-induced inhibition of PIP1-1, PIP2-2, TIP2-2, and NIP1-2 expression in roots, which could help to improve the water transportation and homeostasis from roots to leaves. In addition, the GABA-induced aquaporins expression and decline in endogenous abscisic acid level could improve the heat dissipation capacity through maintaining higher stomatal opening and transpiration in white clovers under high-temperature stress.
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Claims 11
Claim · model-written summary
GABA pretreatment alleviated heat damage in white clover.
- Taxon
- white clover
Trifolium repense0 - Treatment
- GABA pretreatmente0
- Outcome
- damage to white clovere0
- Direction
- alleviatee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“GABA pretreatment could significantly alleviate the damage to white clover during high-temperature stress”
Claim · model-written summary
GABA improved membrane stability, photosynthesis and osmotic adjustment.
- Outcome
- cell membrane stability, photosynthetic capacity, and osmotic adjustment abilitye0
- Direction
- enhancementse0
Not reportedTaxonTreatmentComparator
Verbatim
e0“enhancements in cell membrane stability, photosynthetic capacity, and osmotic adjustment ability”
Claim · model-written summary
GABA lowered oxidative damage and chlorophyll loss.
Not reportedTaxonTreatmentComparator
Verbatim
e0“lower oxidative damage and chlorophyll loss”
Claim · model-written summary
GABA enhanced antioxidant-defense gene expression and enzyme activities.
- Treatment
- GABAe0
- Gene
- superoxide dismutasee0
- Outcome
- gene expression and enzyme activities involved in antioxidant defensee0
- Direction
- enhancede0
Not reportedTaxonComparator
Verbatim
e0“The GABA significantly enhanced gene expression and enzyme activities involved in antioxidant defense, including superoxide dismutase, catalase, peroxidase, and key enzymes of the ascorbic acid–glutathione cycle”
Claim · model-written summary
GABA reduced reactive oxygen species and oxidative injury to membrane lipids and proteins.
- Outcome
- accumulation of reactive oxygen species and the oxidative injury to membrane lipids and proteinse0
- Direction
- reducinge0
Not reportedTaxonTreatmentComparator
Verbatim
e0“reducing the accumulation of reactive oxygen species and the oxidative injury to membrane lipids and proteins.”
Claim · model-written summary
GABA increased root and leaf indole-3-acetic acid content.
- Organ / stage
- roots and leavese0
- Treatment
- GABAe0
- Outcome
- endogenous indole-3-acetic acid contente0
- Direction
- increasede0
Not reportedTaxonComparator
Verbatim
e0“The GABA also increased endogenous indole-3-acetic acid content in roots and leaves”
Claim · model-written summary
GABA increased leaf cytokinin content.
Not reportedTaxonTreatmentComparatorDirection
Verbatim
e0“and cytokinin content in leaves, associated with growth maintenance and reduced leaf senescence under heat stress.”
Claim · model-written summary
GABA upregulated PIP1-1 and PIP2-7 expression in leaves.
Not reportedTaxonComparator
Verbatim
e0“The GABA significantly upregulated the expression of PIP1-1 and PIP2-7 in leaves”
Claim · model-written summary
GABA upregulated TIP2-1 expression in leaves and roots.
Not reportedTaxonTreatmentComparatorDirection
Verbatim
e0“the TIP2-1 expression in leaves and roots under high temperature”
Claim · model-written summary
GABA alleviated heat inhibition of four aquaporin genes in roots.
Not reportedTaxonTreatmentComparator
Verbatim
e0“alleviated the heat-induced inhibition of PIP1-1, PIP2-2, TIP2-2, and NIP1-2 expression in roots”
Claim · model-written summary
GABA-associated aquaporin expression and lower abscisic acid supported stomatal opening and transpiration.
- Taxon
- white cloversTrifolium repense0
- Gene
- aquaporinse0
- Compound
- abscisic acide0
- Outcome
- heat dissipation capacitye0
- Qualifier
- maintaining higher stomatal opening and transpiratione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The GABA-induced aquaporins expression and decline in endogenous abscisic acid level could improve the heat dissipation capacity through maintaining higher stomatal opening and transpiration in white clovers under high-temperature stress.”
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Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.