-Aminobutyric Acid Effectively Postpones Senescence of Strawberry Fruit by Regulating Metabolism of NO, H₂S, Ascorbic Acid, and ABA

Current researchis focused on the influence of beta-aminobutyric acid (BABA) on the metabolism of nitric oxide (NO), hydrogen sulfide (H2S), ascorbic acid, and abscisic acid (ABA) in strawberry fruit. The increases in ion leakage and malondialdehyde (MDA) concentration in strawberry fruit and the degradation of chlorophyll in the sepals of the fruit were markedly inhibited by BABA at 20 mM. BABA-immersed fruit exhibited lower activities and expressions of polygalacturonase (PG), pectinmethylesterase (PME), and ethylene biosynthetic enzymes compared to the control. Furthermore, BABA immersion evidently upgraded the metabolic levels of NO and H2S, including the enzymatic activities and intermediary contents of metabolites, which collectively enhanced the levels of endogenous NO and H2S contents in strawberry fruit. The high enzymatic activities and gene expressions of the AsA biosynthesis pathway jointly maintained AsA accumulation in the BABA-treated sample. The application of BABA led to a decrease in ABA concentration, which was associated with reduced activities and gene expression levels of key enzymes participating in ABA metabolism. Our experimental observations showed that immersion with BABA may be a highly promising means to delay senescence and reduce natural decay in strawberry fruit, and the alleviation in senescence using BABA may be attributed to the modulation of NO, H2S, AsA, and ABA metabolism.