Glutathione and Ascorbic Acid Accumulation in Mango Pulp Under Enhanced UV-B Based on Transcriptome

Mango (<i>Mangifera indica</i>), a nutritionally rich tropical fruit, is significantly impacted by UV-B radiation, which induces oxidative stress and disrupts physiological processes. This study aimed to investigate mango pulp's molecular and biochemical responses to UV-B stress (96 kJ/mol) from the unripe to mature stages over three consecutive years, with samples collected at 10-day intervals. UV-B stress affected both non-enzymatic parameters, such as maturity index, reactive oxygen species (ROS) levels, membrane permeability, and key enzymatic components of the ascorbate-glutathione (AsA-GSH) cycle. These enzymes included glutathione reductase (GR), gamma-glutamyl transferase (GGT), glutathione S-transferases (GST), glutathione peroxidase (GPX), glucose-6-phosphate dehydrogenase (G6PDH), galactono-1,4-lactone dehydrogenase (GalLDH), ascorbate peroxidase (APX), ascorbate oxidase (AAO), and monodehydroascorbate reductase (MDHAR). Transcriptomic analysis revealed 18 differentially expressed genes (DEGs) related to the AsA-GSH cycle, including <i>MiGR</i>, <i>MiGGT1</i>, <i>MiGGT2</i>, <i>MiGPX1</i>, <i>MiGPX2</i>, <i>MiGST1</i>, <i>MiGST2</i>, <i>MiGST3</i>, <i>MiG6PDH1</i>, <i>MiG6PDH2</i>, <i>MiGalLDH</i>, <i>MiAPX1</i>, <i>MiAPX2</i>, <i>MiAAO1</i>, <i>MiAAO2</i>, <i>MiAAO3</i>, <i>MiAAO4</i>, and <i>MiMDHAR</i>, validated through qRT-PCR. The findings suggest that UV-B stress activates a complex regulatory network in mango pulp to optimize ROS detoxification and conserve antioxidants, offering insights for enhancing the resilience of tropical fruit trees to environmental stressors.