Unraveling growth and metabolic dynamics in drought-stressed spinach plants: Exploring the contribution of biological gibberellin

Abstract

Sustainable agriculture is a major theme of the Food and Agriculture Organization (FAO) Strategic Framework 2022–2031. Using microbial-based regulators is a sustainable organic approach to accomplish food safety. Normally, drought is a menace to most crops' agricultural production, but for leafy green vegetables the matter is more frustrating due to grade standards. Despite breakthroughs in boosting crop tolerance to drought stress, the quest for leafy greens remains restricted. The current report is to study the ability of biologically-produced gibberellin by Fusarium oxysporum in alleviating water stress in leafy vegetable spinach, Spinacia oleracea. Endophytic Fusarium oxysporum demonstrated high gibberellin production by 200±5.9 mg L⁻¹. Water stress (100, 75, 50, 25 % field capacity, FC) generated mild to severe abnormal growth and physiological dynamics. Foliar-applied biological gibberellin (BG) motivated plant yield and quality by boosting various phenotypic and physiological features in terms of plant height, biomass, and number of leaves accompanied by thicker epicuticular wax, balanced water status, higher photosynthetic pigment, increased osmoprotectants. BG shoulders a role in upgrading plant liveness via exacerbating antioxidants (anthocyanin, ascorbic acids, total antioxidants, and flavonoids) joined with activation of secondary metabolizing enzyme phenylalanine ammonia-lyase PAL, fulfilling consumer demand standards for spinach as well as lowering the content of phenolics and its oxidizing enzyme polyphenol oxidas (PPO, browning causer). Catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD) were instigated thus maintaining electrolyte leakage, cellular O₂^·−, ^·OH, H₂O₂, malondialdehyde, and lipid peroxidation at baseline levels. BG appears to reduce nitrative toxicity via enhancing nitrate reductase (NR) activity. BG foliar spray increased spinach's resilience to dehydration and its capacity to produce an adequate upgraded yield while cultivated with reduced water regimes or even exposed to drought.