Hydrogen Sulfide and 5-Aminolevulinic Acid Synergistically Enhance Drought Tolerance in Tomato (Solanum lycopersicum L.)

Enhancing crop drought tolerance is crucial for food security amid climate change. This study examines how 5-aminolevulinic acid (ALA) and hydrogen sulfide (H2S) can improve drought resilience in tomato plants, which are essential for sustainable food production. Drought stress was induced using 12% PEG-6000. Plants were pre-treated with 25 mg L-1 ALA and 0.1 mg L(-1)hypotaurine (HT), followed by 0.2 mM sodium hydrosulfide (NaHS) treatment to assess the effects on plant physiological ef-fects over 10 days. Drought stress reduced plant dry weight, chlorophylls (a and b), Fv/Fm, leaf water potential, and relative water content, while increasing glycine betaine (GB) and proline levels. Additionally, drought stress elevated NADPH oxidase (NOX) and glycolate oxidase (GOX) activities, inducing oxidative stress and membrane damage. ALA and NaHS enhanced plant growth, photosynthesis, proline, GB, ALA content, ATP synthase, and ATPase activities, while mitigating NOX and GOX ac-tivities, thereby reducing O & sdot;(-)(2) and H2O2 radicals. ALA alone boosted L-DES activity, promoting H2S accumulation. However, ALA + HT reduced H2S levels, compromising ALA's efficacy. NaHS with ALA + HT reinstated positive effects by restoring H2S levels. Biochemical assays confirmed ALA and NaHS promoted H2S accumulation, bolstering antioxidants, mitigating lipid per-oxidation, suggesting their drought resilience potential in tomatoes.