Ethylene-driven enhancement of bioactive metabolites and in vitro functionality in soybean (Glycine max (L.) Merr.) and mung bean (Vigna radiata (L.) Wilczek) leaves grown in vertical farms: a comparative study

BACKGROUND: Signal-induced augmentation of physiologically active metabolites in edible plants represents a promising approach for the development of high-value-added natural biological resources. Nevertheless, despite the potential of signaling molecules such as ethylene (ETL) to regulate plant metabolism, there are limited systematic studies comparing their organ-specific effects. Therefore, we conducted this comparative study to investigate the effects of ETL treatment on biomass production, accumulation of bioactive metabolites, and associated biological activities in soybean (Glycine max) and mung bean (Vigna radiata) leaves. RESULTS: ETL exposure slightly reduced the plant height and significantly decreased the biomass in both species. Remarkably, ETL-treated mung bean leaves (ML) exhibited the highest total phenolic (24.22 mg GAE/g) and flavonoid (9.89 mg RE/g) contents, whereas soybean leaves (SL) demonstrated greater diversity and accumulation of amino acids such as γ-aminobutyric acid, leucine, and tyrosine. After ETL treatment, the total isoflavone contents increased markedly from 1440.43 to 8703.14 µg/g in SL (~6-folds) and from 2697.71 to 42,708.64 µg/g in ML (~16-folds), indicating a marked increase in isoflavonoid accumulation following ETL treatments. ETL treatment also improved the antioxidant capacity and digestive enzyme inhibition, with ML exhibiting greater radical scavenging activity and stronger inhibitory effects on lipase and α-glucosidase. DNA protection assays further indicated enhanced DNA protective effects against oxidative damage in vitro in both species. Overall, ETL-treated mung bean leaves showed the highest accumulation of secondary metabolites among the tested samples. CONCLUSIONS: Altogether, these results indicate that ETL elicits species-dependent differences in metabolite accumulation patterns and associated in vitro bioactivities, highlighting its potential as an elicitor-based approach for enhancing functional plant resources under controlled cultivation conditions.