Nitrogen is essential for plant development, but the widespread overuse of nitrate-based fertilizers in greenhouse agriculture has created unintended consequences—soil degradation, environmental runoff, and weakened crop quality. Tomatoes, like many vegetables, suffer oxidative stress under nitrate overload, leading to stunted growth and cellular damage. Plants rely on antioxidant systems to survive these conditions, but the genetic regulators driving this resilience remain incompletely understood. Among these, thioredoxins have emerged as redox-sensitive proteins central to plant stress responses. Yet the specific role and regulatory mechanisms of SlTrxh under nitrate stress have remained elusive. Due to these pressing challenges, a deeper exploration of tomato’s molecular stress defenses was urgently needed.
A research team from Kunming University of Science and Technology and partner institutions has unveiled a genetic mechanism that boosts tomato tolerance to nitrate stress. Their findings, published (DOI: 10.1093/hr/uhae184) on July 10, 2024, in Horticulture Research, show that the gene SlTrxh acts as a stress-response regulator whose activity is fine-tuned through S-nitrosation. The study also identified SlMYB86 as a transcription factor that activates SlTrxh expression, forming a two-tiered control system. Using gene editing, protein interaction assays, and stress simulations, the researchers constructed a robust picture of how tomato seedlings fight back against nitrate excess.
The team engineered tomato plants to either overexpress or suppress SlTrxh and exposed them to high-nitrate conditions. Overexpression lines exhibited significantly better growth, longer roots, and reduced oxidative damage, while RNAi lines performed poorly. These plants also showed differing levels of antioxidant enzymes, linking SlTrxh to redox regulation. Crucially, the researchers found that SlTrxh function relies on S-nitrosation—a nitric oxide–driven protein modification—centered on the amino acid cysteine-54. Mutating this residue diminished the plant’s stress tolerance. The team further uncovered that SlTrxh interacts with another protein, SlGrx9, and that this interaction is strengthened by S-nitrosation. Upstream, they identified SlMYB86 as a transcription factor that binds directly to the SlTrxh promoter. When SlMYB86 was overexpressed, tomato plants showed enhanced nitrate tolerance and increased SlTrxh expression; conversely, knockout lines were more vulnerable. These interconnected molecular pathways suggest a sophisticated stress-resistance mechanism controlled by both genetic and redox regulation.
“Our findings shed light on a dynamic molecular defense system in tomatoes,” said Dr. Huini Xu, senior author of the study. “By uncovering how SlMYB86 triggers SlTrxh and how S-nitrosation fine-tunes its activity, we reveal a precise regulatory loop that could be leveraged to improve crop resilience. This dual-layered control system not only reduces cellular damage but also enhances plant vitality under nitrate stress—offering a blueprint for next-generation crop engineering.”
This discovery opens new possibilities for developing tomato varieties that can withstand high-nitrate conditions without compromising growth or quality. Through genetic manipulation of SlMYB86 and SlTrxh, plant breeders may enhance redox balance and improve stress tolerance. Beyond tomatoes, the redox-based regulatory model may apply to other horticultural and staple crops frequently exposed to excessive fertilization. As climate change and food demand intensify the strain on agricultural systems, this research contributes a timely solution to promote sustainable farming and nutrient-efficient cultivation.
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References
DOI
10.1093/hr/uhae184
Original Source URL
https://doi.org/10.1093/hr/uhae184
Funding information
This research was funded by the National Natural Science Foundation of China (Grant Nos. 32260753, 31760582) and the Yunnan Ten Thousand Talents Plan: Young & Elite Talents Project.
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.