Gamma-aminobutyric acid (GABA) is a non-protein amino acid known for its role in the nervous system of animals. However, research has also revealed its presence and function in plants recently. In plants, GABA is a signal molecule involved in multiple physiological processes, including stress response, growth, and development. This review aims to present a thorough summary of the current knowledge regarding the role of GABA in plants. We begin by discussing the biosynthesis and transport of GABA in plants, followed by a detailed examination of its signaling mechanisms. Additionally, we explore GABA's potential roles in various plant physiological processes, such as abiotic stress response, and its potential application in horticultural plants. Finally, we highlight current challenges and future directions for research in this area. Overall, this review offers a comprehensive understanding of the significance of GABA in plants and its potential implications for plant physiology and crop improvement.

Dwarfing rootstocks are a valuable genetic resource for managing high-density plantations. The selection of the appropriate scion/rootstock combination is key to improving crop performance and sustainable production in a particular environment and specific training systems. ‘Shatangju’ mandarin scion cultivar grafted onto ‘Flying Dragon’ rootstock tends to be dwarfing and develops short stature plants. To obtain insight into potential mechanisms underlying rootstock-induced dwarfing effects, we conducted a rootstock trial to examine the influence of 11 different rootstocks based on their growth vigor, antioxidants, and hormonal levels of the scion cultivar. The phenotypic observations revealed that size reduction in the ‘Flying Dragon’ rootstock is due to lower node number, shorter internodal length, and a reduced trunk diameter of the scion compared with more vigorous rootstocks. Antioxidant analysis showed that ‘Shatangju’ mandarin grafted onto ’Flying Dragon’ and ‘Trifoliate Orange’ rootstock had significantly lower peroxidase (POD) activity than other tested rootstocks. The hormonal analysis indicated that there were markedly lower amounts of abscisic acid (ABA) in ‘Shatangju’ mandarin grafted with ‘Flying Dragon’ rootstock. In addition, trees grafted with ‘Sour Pummelo’ and ‘Flying Dragon’ depicted minimum amounts of gibberellins (GA₂₄). Moreover, several metabolites associated with organic acids, flavonoids, amino acids, and alkaloids responded differently in plants grafted with ‘Flying Dragon’ (dwarfing) and ‘Shatang Mandarin’ (vigorous) rootstocks. This study concluded that ‘Flying Dragon’ rootstock with a strong dwarfing effect has been proposed to improve high-density cultivation methods. These findings will provide useful insights for future research associated with rootstock-mediated dwarfing mechanisms of citrus rootstocks.

Grafting has been utilized to develop horticultural crops to increase plant vigor, yield potential, and tolerance to various environmental stresses. Grafting employs selected rootstocks of the same species or near relatives. Moreover, dwarfing is a desirable feature for intensive cultivation and efficient orchard management. However, information on the regulatory mechanisms of rootstock-induced vigor control remains unclear. Numerous studies comprehend the physiological and molecular mechanism of rootstock control scion vigor, which has significantly improved our understanding regarding vigor control processes in apple, litchi, pear, citrus, etc. This review summarizes the current knowledge on the impact of rootstocks on scion vigor and hormonal mechanisms involved in dwarfing, such as auxin (IAA), cytokinins (CK), abscisic acid (ABA), gibberellic acids (GAs), and brassinosteroids (BR). This study will provide fascinating information for future studies on rootstock-induced dwarfing effects and accelerate the breeding of dwarfing rootstocks.

Air- and sun-dried raisins from Thompson Seedless (TS) grapes were analyzed under GC/MS to evaluate fatty acids (FAs) and their derived volatile compounds, coming from unsaturated fatty acids oxidation. A total of 16 FAs were identified in TS raisins, including 10 saturated fatty acids (SFAs) and 6 unsaturated fatty acids (USFAs). The contents of C18:0, C15:0, and C16:0 among SFAs and C18:3, C18:2 and C18:1 in USFAs were significantly higher. Furthermore, USFAs such as C16:1 and C20:1 were only identified in air-dried raisins. The principal component analysis showed the increased content of FAs and FA-derived compounds were in air-dried and sun-dried raisins, respectively. Among FA-derived compounds, 2-pentyl furan, 3-octen-2-one, 1-hexanol and heptanoic acid were more potent. This study shows that air-drying is more favorable for the production of fatty acids (SFAs and USFAs), whereas sun-drying is more advantageous in terms of fatty acid-derived volatiles.

Litchi’s post-harvest pericarp browning is one of the main constraints that drastically affect its visual attributes and market potential. Therefore, the vanillin-taurine Schiff base (VTSB) compound prepared from natural compounds of vanillin and taurine exhibited higher DPPH-radical-scavenging invitro antioxidant activity than vanillin. VTSB first-time report to mitigate the postharvest browning of litchi fruit. In this study, litchi fruits were dipped in 0.3 mM (based on pre-experiment) VTSB solution and stored at 25 ± 1 °C for six days to examine their effects on browning and postharvest quality. Fruit treated with VTSB had lower levels of browning degree (BD), browning index (BI), weight loss, soluble quinone (SQ), relative electrolyte leakage (REL), and malondialdehyde (MDA) than control fruit. Additionally, total anthocyanins and phenolic concentrations, Total soluble solids (TSS), and 2,2-diphenyl-1-picrylhydrazyl-free radical scavenging activity (DPPH-RSA) were preserved higher in VTSB-treated litchi fruit. The levels of Ascorbate peroxidase (APX), Superoxide dismutase (SOD), and Catalase (CAT) were higher in treated fruit, whereas polyphenol oxidase (PPO) and Peroxidase (POD) were decreased during the postharvest period. This study suggested that VTSB would be very useful for different post-harvest problems in the fruit and vegetable industry.