Abstract
Aroma is a key quality trait determining the flavor and market competitiveness of pumpkins. Its characteristic fragrance mainly comes from 2-acetyl-1-pyrroline (2-AP), whose biosynthesis shares the common precursor with γ-aminobutyric acid (GABA) metabolic pathway. However, it remains unclear whether and how exogenous GABA regulates 2-AP synthesis in pumpkin. Given that the 2-AP biosynthetic pathway is highly conserved across various plant tissues, understanding its regulatory mechanisms in leaves provides a fundamental framework for improving fruit aroma quality. This study investigated the effects of exogenous GABA on 2-AP biosynthesis in pumpkin seedlings and elucidated the underlying regulatory mechanisms by analyzing key precursors, metabolic enzyme activities, and related gene expression. Foliar application of 500 mg L⁻¹ GABA significantly increased the 2-AP content in pumpkin leaves by 72.4%, and promoted seedling growth, with leaf area and fresh weight increasing by 57.7% and 58.4%, respectively. GABA treatment markedly elevated glutamate (Glu) content by 7.8-fold and reduced proline (Pro) levels by 13.6% at 30 h. Furthermore, GABA application enhanced the activities and gene expression of Δ¹-pyrroline-5-carboxylate synthase (P5CS) and proline dehydrogenase (ProDH), while suppressing those of betaine aldehyde dehydrogenase (BADH), thereby coordinately directing metabolic flux toward 2-AP synthesis. These findings demonstrate that exogenous GABA effectively promotes 2-AP biosynthesis in pumpkin by enriching the Glu pool and coordinately regulating key enzymes to suppress competitive metabolic pathways. This study provides a theoretical foundation for utilizing GABA as a biostimulant to improve aroma quality in pumpkin.
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Claims 9
Claim · model-written summary
Foliar 500 mg L⁻¹ GABA increased pumpkin leaf 2-AP content by 72.4%.
- Taxon
- pumpkine0
- Organ / stage
- leavese0
- Treatment
- Foliar application of 500 mg L⁻¹ GABAe0
- Outcome
- 2-AP contente0
- Direction
- increasede0
- Value
- 72.4%e0
Not reportedComparator
Verbatim
e0“Foliar application of 500 mg L⁻¹ GABA significantly increased the 2-AP content in pumpkin leaves by 72.4%”
Claim · model-written summary
GABA increased pumpkin seedling leaf area by 57.7%.
Not reportedComparator
Verbatim
e0“GABA significantly increased the 2-AP content in pumpkin leaves by 72.4%, and promoted seedling growth, with leaf area and fresh weight increasing by 57.7% and 58.4%, respectively”
Claim · model-written summary
GABA increased pumpkin seedling fresh weight by 58.4%.
Not reportedComparator
Verbatim
e0“leaf area and fresh weight increasing by 57.7% and 58.4%, respectively”
e1“GABA significantly increased the 2-AP content in pumpkin leaves”
Claim · model-written summary
GABA increased glutamate content 7.8-fold at 30 h.
- Taxon
- pumpkine1
- Treatment
- GABA treatmente0
- Outcome
- glutamate (Glu) contente0
- Direction
- elevatede0
- Value
- 7.8-folde0
- Qualifier
- at 30 he0
Not reportedComparator
Verbatim
e0“GABA treatment markedly elevated glutamate (Glu) content by 7.8-fold and reduced proline (Pro) levels by 13.6% at 30 h”
e1“pumpkin seedlings”
Claim · model-written summary
GABA reduced proline levels 13.6% at 30 h.
- Taxon
- pumpkine1
- Treatment
- GABA treatmente0
- Outcome
- proline (Pro) levelse0
- Direction
- reducede0
- Value
- 13.6%e0
- Qualifier
- at 30 he0
Not reportedComparator
Verbatim
e0“GABA treatment markedly elevated glutamate (Glu) content by 7.8-fold and reduced proline (Pro) levels by 13.6% at 30 h”
e1“pumpkin seedlings”
Claim · model-written summary
GABA enhanced P5CS activity and expression.
- Taxon
- pumpkine1
- Treatment
- GABA applicatione0
- Gene
- Δ¹-pyrroline-5-carboxylate synthase (P5CS)e0
- Outcome
- activities and gene expressione0
- Direction
- enhancede0
Not reportedComparator
Verbatim
e0“GABA application enhanced the activities and gene expression of Δ¹-pyrroline-5-carboxylate synthase (P5CS) and proline dehydrogenase (ProDH)”
e1“pumpkin seedlings”
Claim · model-written summary
GABA enhanced ProDH activity and expression.
- Taxon
- pumpkine1
- Treatment
- GABA applicatione0
- Gene
- proline dehydrogenase (ProDH)e0
- Outcome
- activities and gene expressione0
- Direction
- enhancede0
Not reportedComparator
Verbatim
e0“GABA application enhanced the activities and gene expression of Δ¹-pyrroline-5-carboxylate synthase (P5CS) and proline dehydrogenase (ProDH)”
e1“pumpkin seedlings”
Claim · model-written summary
GABA suppressed BADH activity and expression.
- Taxon
- pumpkine1
- Treatment
- GABAe2
- Gene
- betaine aldehyde dehydrogenase (BADH)e0
- Outcome
- activities and gene expressione2
- Direction
- suppressinge0
Not reportedComparator
Verbatim
e0“while suppressing those of betaine aldehyde dehydrogenase (BADH)”
e1“pumpkin seedlings”
e2“GABA application enhanced the activities and gene expression”
Claim · model-written summary
The authors infer GABA promotes 2-AP biosynthesis through glutamate enrichment and coordinated enzyme regulation.
Verbatim
e0“exogenous GABA effectively promotes 2-AP biosynthesis in pumpkin by enriching the Glu pool and coordinately regulating key enzymes to suppress competitive metabolic pathways”
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gamma-aminobutyric acid · molecular: metabolites · Cucurbita (pumpkins)Results agree
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- positive
application · molecular: metabolites · Cucurbita (pumpkins)Positive and negative results
4 papers in the same direction as this paper · 1 in the opposite direction
- negative
- positive
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2 papers more in this group
See all 6 papers →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.