Boosting NADPH with GABA: Converting aged seeds to functional soybean sprouts.

Area of Science:

• Plant Science
• Biochemistry
• Agricultural Science

Background:

• Seed aging significantly reduces soybean germination and nutritional quality.
• The pentose phosphate pathway (PPP) plays a crucial role in cellular redox balance and biosynthesis.
• Gamma-aminobutyric acid (GABA) is a non-proteinogenic amino acid with potential roles in plant stress response.

Purpose of the Study:

• To investigate the mechanism by which GABA revitalizes aged soybean seeds.
• To determine the role of the pentose phosphate pathway (PPP) in GABA-mediated seed revitalization.
• To assess the impact of GABA treatment on germination, antioxidant status, and metabolite profiles of aged soybean seeds.

Main Methods:

• Aged soybean seeds were treated with GABA, a glucose-6-phosphate dehydrogenase (G6PDH) inhibitor, or a combination.
• Pharmacological inhibition was used to confirm PPP dependency.
• Key physiological parameters, enzyme activities, gene expression, antioxidant capacity, redox ratios, and metabolite profiles were analyzed.

Main Results:

• GABA treatment significantly restored germination rates (35% to 72%) and enhanced G6PDH activity (225%).
• Antioxidant capacity (FRAP) and key redox ratios (AsA/DHA, GSH/GSSG, NADPH/NADP+) were restored to levels near those of fresh seeds.
• Metabolomic analysis revealed GABA specifically activated PPP intermediates and isoflavone biosynthesis, leading to increased endogenous GABA levels.

Conclusions:

• GABA revitalizes aged soybean seeds primarily by activating the PPP, which replenishes NADPH and enhances antioxidant defenses.
• This activation leads to improved germination, nutritional quality, and the production of dual-functional sprouts.
• GABA treatment presents a promising strategy to mitigate storage-related losses in soybean seeds.