The study, published in the Journal of Agriculture and Food Research, focused on Fusarium oxysporum f. sp. fabae, a soil-borne fungus that causes devastating wilt in faba bean. Farmers in Yunnan Province have long observed that growing wheat alongside faba bean reduces wilt incidence, but the underlying chemistry remained murky. The new work, led by Bijie Hu and colleagues, connects the dots across three levels: the signals released by sick faba bean roots, the defensive compounds those signals induce in wheat, and the lethal effects of those compounds on the pathogen itself.

The team began with hydroponic experiments in which faba bean plants were grown alone or alongside wheat, and then subjected to three kinds of stress: the fungal pathogen itself, cinnamic acid as a stand-in for abiotic stress, and both together. Using untargeted metabolomics of root exudates, they found dramatic shifts in the chemical composition of what stressed faba bean roots released into their surroundings. Under combined stress, more than 770 differential metabolites were detected compared with unstressed monoculture plants, with the vast majority upregulated.

Pathway analysis pointed consistently toward secondary metabolism, including flavonoid biosynthesis and plant hormone signal transduction. When the researchers screened for metabolites that were upregulated across every stress treatment, four candidates stood out: jasmonic acid, salicylic acid, allantoin, and luteolin. Quantitative measurements confirmed that faba bean boosted secretion of these compounds under biotic and abiotic stress alike, and that intercropping pushed the levels even higher. In field plots, intercropping raised jasmonic acid in the root zone by nearly 64 percent, salicylic acid by about 46 percent, and allantoin by roughly 15 percent compared with faba bean grown alone.

These molecules are well-known players in plant stress biology. Jasmonic acid and salicylic acid are classic defense hormones, while allantoin is a nitrogen-rich metabolite linked to oxidative stress responses. The authors interpret their coordinated release as a broadcast distress call, a chemical SOS that neighboring plants can detect and respond to. Analogous systems have been documented elsewhere: chili plants under attack induce benzoxazinoid production in adjacent corn, and barnyard grass releases jasmonic acid that prompts rice to pump out allelopathic compounds.

To test whether wheat actually listens, the team applied jasmonic acid, salicylic acid, and allantoin exogenously to wheat at concentrations matching those found in faba bean exudates, then measured benzoxazinoid levels in wheat leaves and rhizosphere soil. The response was clear. Salicylic acid treatment raised DIMBOA content in wheat leaf tissue by up to 96 percent and MBOA by nearly 60 percent. Jasmonic acid and allantoin produced similarly robust, dose-dependent increases. Crucially, the benzoxazinoids also accumulated in the rhizosphere soil, confirming that wheat not only synthesized the compounds but secreted them into the soil where the pathogen lives.

Benzoxazinoids such as DIMBOA and MBOA are defensive secondary metabolites produced almost exclusively by grasses, the Poaceae family that includes wheat, maize, and their relatives. The next question was what these compounds do to the fungus. In a clever microscopy setup using capillary grooves on glass slides, the researchers observed that FOF spores actively accumulate in the wheat rhizosphere, with numbers rising over 20 minutes of observation. Rather than avoiding wheat, the pathogen is drawn toward it, a positive chemotactic response that previous work suggests is driven in part by the benzoxazinoids themselves.

That attraction sets up what the authors describe as an “attract-and-kill” strategy. In liquid culture, DIMBOA and MBOA reduced FOF mycelial biomass in a concentration-dependent manner, with the strongest suppression at 150 micrograms per milliliter, cutting fungal growth by roughly 38 percent. Fluorescent staining revealed that the compounds also crippled biofilm formation, a key step in fungal establishment, and induced apoptotic vesicles in FOF spores, hallmarks of programmed cell death. The mechanism, the authors suggest, involves reactive oxygen species: benzoxazinoids trigger bursts of intracellular ROS that overwhelm the fungus’s antioxidant defenses, damaging mitochondrial and cytoplasmic function until the cells die.

Perhaps the most surprising finding came from germination tests. Far from being toxic to the crop it protects, the wheat-derived benzoxazinoids actually stimulated faba bean seed germination. DIMBOA treatment increased germination potential, germination index, vigor index, and seedling length, with vigor index gains reaching nearly 900 percent under some conditions, and the effects held even when seeds were simultaneously challenged with the pathogen. The authors speculate that benzoxazinoids may act somewhat like hormones, stimulating cell division and metabolic activity in germinating seeds, though they caution that the precise mechanism remains to be established.

Taken together, the study sketches a complete chemical circuit: a stressed faba bean root releases jasmonic acid, salicylic acid, and allantoin; wheat senses these signals and ramps up benzoxazinoid biosynthesis and secretion; the pathogen, lured by chemotactic cues, gathers at the wheat rhizosphere where the accumulated DIMBOA and MBOA suppress its growth, dismantle its biofilms, and push its cells into programmed death. The authors are careful to note that the links between exudate composition, benzoxazinoid induction, and fungal viability are associations, and that further work is needed to fully establish the causal mechanisms, including quantifying spore apoptosis with flow cytometry. Even so, the findings offer a compelling blueprint for disease-suppressive agriculture, suggesting that the right crop combinations can turn a field into a coordinated chemical defense network, reducing reliance on fungicides while potentially giving seedlings a head start. In an era when crop diversity is increasingly promoted for sustainable intensification, this underground conversation between a legume and a grass shows just how sophisticated plant-plant communication can be, and how much agronomic value may be hiding in the chemistry of the rhizosphere.

Subject of Research: Chemical communication between faba bean and wheat roots that induces benzoxazinoid defenses suppressing Fusarium wilt

Article Title: Root exudate-mediated plant chemical communication induces benzoxazinoid synthesis in wheat and suppresses Fusarium oxysporum f. sp. fabae activity in faba bean

Article References: Hu, B., Li, T., Yang, S., & Dong, Y. (2026). Root exudate-mediated plant chemical communication induces benzoxazinoid synthesis in wheat and suppresses Fusarium oxysporum f. sp. fabae activity in faba bean. Journal of Agriculture and Food Research, 31, Article 103324. https://doi.org/10.1016/j.jafr.2026.103324

Image Credits: AI Generated

DOI: 10.1016/j.jafr.2026.103324

Keywords: intercropping, root exudates, benzoxazinoids, DIMBOA, MBOA, jasmonic acid, salicylic acid, Fusarium oxysporum, faba bean wilt, plant chemical communication, attract-and-kill, rhizosphere

The study, published in Plant Cell Reports, combined physiology, transcriptomics, metabolomics, and enzyme assays to trace exactly how exogenous trehalose bolsters salt tolerance in tomato seedlings. The findings reveal that hydrogen sulfide acts as a central mediator in trehalose-induced protection, and that the downstream response funnels through two metabolic routes: the phenylpropanoid pathway, a workhorse of plant defense chemistry, and the less celebrated cyanoamino acid metabolism pathway, which processes cyanogenic compounds. The work offers a clearer mechanistic picture of how two stress-protective agents interact, and it hints at practical strategies for shielding crops from salinity.

Trehalose is no stranger to stress biology. This disaccharide, composed of two glucose units, accumulates in an astonishing range of organisms, from resurrection plants that survive near-total desiccation to yeast cells braving heat and dehydration. In plants, trehalose and its phosphorylated precursor trehalose-6-phosphate serve dual roles as osmoprotectants that stabilize proteins and membranes, and as sugar signals that rewire metabolism during stress. Previous studies had shown that spraying tomato seedlings with trehalose improves their performance under salt stress by modulating reactive oxygen species, photosynthesis, and osmolyte synthesis. Hydrogen sulfide, meanwhile, has shed its reputation as merely a toxic, rotten-egg-smelling gas. Over the past two decades, plant biologists have established that H2S functions as a genuine signaling molecule, regulating seed germination, stomatal closure, and a broad spectrum of abiotic stress responses, often through persulfidation, a chemical modification that alters the activity of target proteins.

What remained unknown was how these two protective agents relate to each other when deployed together. The Guangxi team, led by corresponding author Changxia Li with co-first authors Jin Qi and Zhang Zhang, designed a series of experiments to answer that question. They grew tomato seedlings under salt stress and treated them with trehalose alone, with sodium hydrosulfide (NaHS), a donor of hydrogen sulfide, alone, or with both compounds simultaneously. The physiological results were striking: both treatments significantly alleviated salt-induced growth inhibition, but the combined treatment produced the most pronounced protective effect, suggesting the two agents act in complementary or synergistic ways.

To dissect the direction of the relationship, the researchers turned to pharmacology. They applied validamycin A, an inhibitor of trehalose biosynthesis, and hypotaurine, a chemical scavenger that mops up hydrogen sulfide. The logic was simple but powerful: if removing hydrogen sulfide abolishes trehalose’s benefits, then trehalose must depend on the gas to work. The experiments delivered a clear verdict. The protective effect of trehalose was largely dependent on hydrogen sulfide, because scavenging the gas with hypotaurine substantially undermined trehalose-induced salt tolerance. In contrast, the efficacy of the NaHS donor was independent of trehalose, indicating a one-directional dependency: trehalose needs hydrogen sulfide, but hydrogen sulfide does not need trehalose. The authors are careful to note the limits of this interpretation. Their data mainly support a requirement for H2S in trehalose action rather than demonstrating that hydrogen sulfide alone is sufficient to reproduce the full trehalose response, and they call for further functional analyses to clarify the precise hierarchy between the two signals.

With the physiological dependency established, the team moved to the molecular level using RNA sequencing. The transcriptomic analysis showed that trehalose modulates the salt stress response of tomato seedlings at the transcriptional level via hydrogen sulfide, and it pinpointed phenylalanine biosynthesis as a core metabolic target. Phenylalanine is the gateway amino acid for the phenylpropanoid pathway, one of the most important specialized metabolic networks in plants. From phenylalanine, plants build an enormous arsenal of compounds, including lignin, which reinforces cell walls and forms apoplastic barriers against ion intrusion; flavonoids and anthocyanins, which act as antioxidants; and a variety of phenolic compounds that buffer oxidative damage. The second pathway flagged by the analysis was cyanoamino acid metabolism, the route that produces and processes cyanogenic glycosides, nitrogen-containing defense metabolites derived from amino acids.

The metabolomic data reinforced the transcriptomic picture. Compared with seedlings receiving salt plus trehalose, those that also received the hydrogen sulfide scavenger hypotaurine showed significantly reversed accumulation of protective metabolites. In the phenylpropanoid pathway, the compounds p-coumaryl alcohol and coniferyl alcohol, both monolignols that feed into lignin biosynthesis, accumulated in response to trehalose but dropped back when hydrogen sulfide was removed. In the cyanoamino acid pathway, the cyanogenic glycosides amygdalin and prunasin, compounds more famous for their roles in almond and stone fruit bitterness, followed the same pattern. This is a notable finding because it implicates a pathway usually discussed in the context of herbivore defense in abiotic stress tolerance, adding to a growing body of evidence that cyanogenic metabolism contributes to how plants cope with environmental challenges.

The enzymatic and gene expression data tied the whole story together. The salt plus trehalose treatment significantly elevated the activities of key enzymes in the phenylpropanoid biosynthesis pathway, including 4-coumarate-CoA ligase (4CL), caffeoyl-CoA O-methyltransferase (CCoAOMT), and peroxidase (POD), as well as enzymes in the cyanoamino acid metabolism pathway, namely mandelonitrile lyase (MDL) and beta-glucosidase (bglX). Consistent with these biochemical changes, the transcript levels of the corresponding encoding genes, including 4CL1, CCoAOMT, POD9, POD43, MDL3, and bglX1, were significantly upregulated. When hypotaurine was added to scavenge hydrogen sulfide, the trehalose-induced enhancement of both enzyme activities and gene expression was significantly reversed. At the molecular level, this confirms that hydrogen sulfide sits upstream of these metabolic changes, serving as a central mediator through which trehalose exerts its protective influence during salt stress.

Why does this matter beyond the laboratory? Salinity stress imposes a double burden on plants: excess sodium ions are toxic, and the osmotic stress they create makes it harder for roots to take up water. Plants respond with a suite of defenses, including osmolyte accumulation, ion homeostasis, and antioxidant systems that neutralize the reactive oxygen species generated under stress. The phenylpropanoid pathway sits at the heart of several of these defenses, supplying lignin for physical barriers and phenolic compounds for antioxidant protection. If trehalose triggers these defenses only through hydrogen sulfide, then breeding or engineering approaches might target the signaling relay itself, for instance by enhancing H2S production capacity or persulfidation of key regulatory proteins, to amplify a crop’s intrinsic stress response. Alternatively, combined field treatments of trehalose and hydrogen sulfide donors could be optimized to exploit the synergy observed in seedlings, though translating greenhouse pharmacology to open-field agriculture always demands careful validation.

The study also enriches a rapidly expanding literature on hydrogen sulfide as a master regulator of plant stress resilience. Recent work has shown that H2S promotes lateral root formation in peach through persulfidation of the SnRK1α kinase, balances hydrogen sulfide and hydrogen cyanide homeostasis in Arabidopsis under osmotic stress, and modulates phenolic metabolism to alleviate salt stress in tomato. The Guangxi findings slot neatly into this picture while adding a new layer: they position trehalose, a sugar signal, upstream of the gas, and they extend the downstream reach of the gas into cyanoamino acid metabolism, a pathway rarely invoked in salt tolerance research. The authors acknowledge that much remains to be resolved, particularly whether hydrogen sulfide alone can reproduce the complete trehalose response and what the precise hierarchical relationship between the two signals looks like under field conditions. But the core message is already compelling: in salt-stressed tomato seedlings, a protective sugar whispers its instructions through a stinky gas, and the plant listens by building stronger walls and richer chemistry. For a crop that feeds billions and a planet whose farmland grows saltier by the season, that conversation is worth every effort to understand and, ultimately, to harness.

Subject of Research: Hydrogen sulfide-dependent trehalose signaling that enhances salt tolerance in tomato seedlings through phenylpropanoid and cyanoamino acid metabolism

Article Title: H2S-dependent trehalose-induced salt tolerance in tomato involves phenylpropanoid and cyanoamino acid pathways

Article References: Qi, J., Zhang, Z., Li, S., Su, J., Tian, Y., Yu, W., & Li, C. (2026). H2S-dependent trehalose-induced salt tolerance in tomato involves phenylpropanoid and cyanoamino acid pathways. Plant Cell Reports, 45(10), Article 283. https://doi.org/10.1007/s00299-026-03969-5

Image Credits: AI Generated

DOI: 10.1007/s00299-026-03969-5

Keywords: trehalose, hydrogen sulfide, salt stress, tomato, phenylpropanoid pathway, cyanoamino acid metabolism, transcriptomics, plant stress signaling, sodium hydrosulfide, hypotaurine, antioxidant defense, Plant Cell Reports

The research, led by Jiao Zhang, Xin Wang and Xiaofeng Zhang of Shanxi University in Taiyuan, China, under the corresponding authors Yanxi Pei and Zhuping Jin, focuses on an enzyme called electron transfer flavoprotein: ubiquinone oxidoreductase, or ETFQO. This protein sits in the inner mitochondrial membrane and serves as a metabolic escape hatch. When carbohydrates run low, the cell can break down amino acids such as lysine and branched-chain amino acids, and ETFQO channels the electrons liberated from that breakdown into the mitochondrial electron transport chain, allowing respiration to continue even when the usual fuel supply has collapsed.

What makes the new work striking is the discovery that hydrogen sulfide does not simply switch ETFQO on or off. Instead, it manipulates the enzyme at two levels simultaneously. At the transcriptional level, both hydrogen sulfide treatment and drought stress increase the expression of the ETFQO gene, producing more of the raw material for the protein. But the team’s transcriptome sequencing revealed something more subtle: hydrogen sulfide also changes how the ETFQO pre-messenger RNA is spliced, the process by which non-coding introns are removed and coding sequences are stitched together before a protein is made.

Alternative splicing is one of the most powerful sources of biological complexity in higher organisms. A single gene can yield multiple protein variants, called isoforms, each with potentially different structures and functions. In the case of ETFQO, the researchers found that hydrogen sulfide modulates splicing under stress conditions so that three distinct transcripts accumulate, which they named ETFQO.1, ETFQO.2 and ETFQO.3. These isoforms are not interchangeable, and the physiological experiments demonstrated that their roles diverge in ways that matter for survival.

To test what each isoform actually does, the team generated Arabidopsis thaliana plants that overexpress each of the three transcripts individually. The results were clear-cut. Plants overexpressing ETFQO.3 showed improved drought tolerance, while those overexpressing ETFQO.1 or ETFQO.2 did not gain any such advantage. Yet the story does not end there. Both ETFQO.1 and ETFQO.3 participated in the hydrogen sulfide-modulated control of stomatal closure and mitochondrial respiration, and both responded more strongly to the gas than ETFQO.2 did. In other words, only one isoform directly confers drought resistance, but two of the three serve as responsive partners in the broader gasotransmitter-driven stress program.

The explanation for this functional specificity lies in a chemical modification known as persulfidation. Hydrogen sulfide can attach a sulfur atom to reactive cysteine residues on target proteins, converting their thiol groups into persulfides and thereby altering their activity, stability or interaction partners. This modification has emerged over the past decade as the principal way hydrogen sulfide transmits signals in cells, operating alongside better-known systems such as phosphorylation and nitric oxide-dependent S-nitrosylation. In guard cells, for example, persulfidation of the protein kinase SnRK2.6 has already been shown to link hydrogen sulfide to abscisic acid signaling, the central hormonal pathway governing stomatal behavior.

In the new study, the mechanistic experiments showed that hydrogen sulfide induces persulfidation of ETFQO.1 and ETFQO.3, but that the same modification is absent from ETFQO.2. This single biochemical difference appears to explain why the first two isoforms are responsive to the gas while the third is not, and why only ETFQO.3, the persulfidated variant that also carries the right structural features, delivers actual drought tolerance when overexpressed. The finding illustrates how alternative splicing and post-translational modification can act in concert: splicing generates a menu of protein variants, and persulfidation selects and tunes which of them participate in the stress response.

The broader significance of the work lies in how it reframes the role of hydrogen sulfide in plant energy metabolism. Previous research from the same and other groups had established that the gas regulates stomatal movements through multiple targets, including S-type anion channels via the OST1 kinase and calcium modules, potassium channels, and succinate dehydrogenase, which the same team showed is activated by persulfidation to induce stomatal closure in Arabidopsis. Hydrogen sulfide has also been shown to modulate alternative splicing of other targets, such as the succinate dehydrogenase gene BrSDH1-1 in Chinese cabbage and the splicing factors AtU2AF65a and BraATO2, which influence flowering. The new study extends this regulatory logic deep into the mitochondrion, showing that a gasotransmitter can coordinate the respiratory machinery that sustains the cell when photosynthesis falters.

This coordination is precisely what a drought-stressed plant needs. Closing stomata saves water but starves the leaf of carbon dioxide, so the tissue must re-balance its energy budget. By promoting ETFQO expression, reshaping its splicing pattern and persulfidating the resulting isoforms, hydrogen sulfide simultaneously supports the respiratory recycling of amino acids and the stomatal decisions that determine how much water the plant loses. The authors describe this as a coordinated transcriptional and post-translational mechanism that integrates alternative splicing with persulfidation to optimize drought adaptation, a model that advances understanding of how gasotransmitters function in stress responses.

The practical implications could be considerable. Drought is among the most damaging abiotic stresses for global agriculture, and engineering crops with enhanced stress resilience is a major goal of plant biotechnology. Because ETFQO.3 overexpression alone improved drought tolerance in Arabidopsis, the isoform represents a candidate target for breeding or genome editing programs aimed at producing crop varieties that endure water scarcity more effectively. More broadly, the study suggests that manipulating hydrogen sulfide signaling, or the splicing and persulfidation machinery it engages, could offer new strategies for crop improvement. As with all results established in a model organism, translating the findings into staple crops will require further work, but the identification of a single enzyme controlled through two converging regulatory layers provides a concrete molecular handle for that effort.

Subject of Research: Hydrogen sulfide regulation of ETFQO alternative splicing and persulfidation in plant drought tolerance

Article Title: H2S enhances drought resistance by orchestrating alternative splicing and persulfidation of ETFQO

Article References: Zhang, J., Wang, X., Zhang, X., Zhang, L., Pei, Y., & Jin, Z. (2026). H2S enhances drought resistance by orchestrating alternative splicing and persulfidation of ETFQO. Plant Cell Reports, 45(10), Article 312. https://doi.org/10.1007/s00299-026-04006-1

Image Credits: AI Generated

DOI: 10.1007/s00299-026-04006-1

Keywords: hydrogen sulfide, ETFQO, alternative splicing, persulfidation, drought stress, Arabidopsis thaliana, mitochondrial respiration, stomatal closure, gasotransmitter, plant stress signaling, energy metabolism, crop improvement