Tomato (Solanum lycopersicum L.) is one of the world's most widely grown vegetables, but high temperature can quickly reduce growth and productivity. Heat stress drives the accumulation of reactive oxygen species (ROS), including hydrogen peroxide (H₂O₂), which can damage membranes if antioxidant defenses cannot keep pace. At the same time, plants must adjust stomata, the tiny pores that regulate cooling, water retention, and carbon dioxide uptake. Previous studies suggested that H₂S participates in heat responses, but much of the evidence came from chemical treatments rather than direct genetic tests. Based on these challenges, there is a need to conduct in-depth research into how tomato plants connect hydrogen sulfide (H₂S) signaling with oxidative control and stomatal regulation.
Researchers from the Key Laboratory of Quality and Safety Control for Subtropical Fruit and Vegetable, Ministry of Agriculture and Rural Affairs, the Key Laboratory of Vegetable Germplasm Innovation and Quality Breeding in the Province, and the College of Horticulture at Zhejiang A&F University investigated this question in tomato seedlings. Published (DOI: 10.1093/hr/uhag090) on March 9, 2026, in Horticulture Research, the study examined how H₂S produced through L-cysteine desulfhydrase (L-CDes) and the SlLCD1 gene improves tomato heat tolerance by strengthening antioxidant capacity and modulating stomatal behavior.
The team exposed six-true-leaf tomato plants to 44°C heat and followed changes in H₂S production, enzyme activity, leaf water status, oxidative damage, stomata, and photosynthesis. Heat rapidly induced SlLCD1 expression, and L-CDes activity rose to 2.71-fold the baseline by 3 hours, supporting a transient burst of endogenous H₂S. To test causality, the researchers combined three approaches: SlLCD1 overexpression, exogenous H₂S treatment, and clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9)-generated SlLCD1 mutants. Plants overexpressing SlLCD1 and plants pretreated with H₂S showed higher relative water content (RWC), larger leaf wilting angles, and fewer severely wilted or scorched leaves than wild-type (WT) plants under heat stress. The 100 micromolar (μM) H₂S treatment performed better than 50 μM and was used for rescue tests. By contrast, SlLCD1-edited mutants produced less H₂S, wilted faster, and accumulated more ROS. Exogenous H₂S rescued much of this heat-sensitive phenotype, reducing relative electrolyte leakage (REL), malondialdehyde (MDA), H₂O₂, and superoxide anion (O₂−). It also restored antioxidant responses involving superoxide dismutase (SOD), peroxidase (POD), ascorbate peroxidase (APX), catalase (CAT), glutathione reductase (GR), reduced glutathione (GSH), and ascorbic acid (AsA). Beyond redox control, the SlLCD1-H₂S module helped regulate stomatal density and aperture, with H₂O₂ likely acting downstream in stomatal closure, and protected photosystem II (PSII) efficiency under heat.
The authors said the work places SlLCD1-derived H₂S at the center of tomato's heat-response network. They said the signal does not act through a single protective route; instead, it helps the plant manage several connected pressures at once: excess ROS, water loss, stomatal adjustment, and photosynthetic stability. This integrated response is especially important because heat-tolerant crops must do more than avoid visible wilting. They must keep leaves alive and functional long enough to recover when extreme temperatures pass. They said this gives breeders and physiologists a clearer entry point for testing heat-resilient tomato lines.
The discovery offers a tractable target for improving tomato resilience in warming production environments. Because SlLCD1 influences multiple heat-protective traits, it may support future breeding, marker development, or precision improvement strategies for heat-tolerant cultivars. The results may also guide research on H₂S-related agronomic treatments, although field validation will be needed to define safe and effective timing, dosage, and growth-stage responses. More broadly, the study links gas signaling to crop climate adaptation, showing how a small endogenous molecule can help coordinate antioxidant defense, water balance, and photosynthetic protection during heat stress in both greenhouse and open-field production systems.
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References
DOI
10.1093/hr/uhag090
Original Source URL
https://doi.org/10.1093/hr/uhag090
Funding information
This research was supported by the National Natural Science Foundation of China, 32102367 and 32272742.
About Horticulture Research
Horticulture Research is an open access journal of Nanjing Agricultural University and ranked number one in the Horticulture category of the Journal Citation Reports ™ from Clarivate, 2023. The journal is committed to publishing original research articles, reviews, perspectives, comments, correspondence articles and letters to the editor related to all major horticultural plants and disciplines, including biotechnology, breeding, cellular and molecular biology, evolution, genetics, inter-species interactions, physiology, and the origination and domestication of crops.