The important life-supporting role of hydrogen sulfide (H2S) has evolved from bacteria to plants, invertebrates, vertebrates, and finally to mammals. Over the centuries, however, H2S had only been known for its toxicity and environmental hazard. Physiological importance of H2S has been appreciated for about a decade. It started by the discovery of endogenous H2S production in mammalian cells and gained momentum by typifying this gasotransmitter with a variety of physiological functions. The H2S-catalyzing enzymes are differentially expressed in cardiovascular, neuronal, immune, renal, respiratory, gastrointestinal, reproductive, liver, and endocrine systems and affect the functions of these systems through the production of H2S. The physiological functions of H2S are mediated by different molecular targets, such as different ion channels and signaling proteins. Alternations of H2S metabolism lead to an array of pathological disturbances in the form of hypertension, atherosclerosis, heart failure, diabetes...

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Physiological Implications of Hydrogen Sulfide: A Whiff Exploration That Blossomed

Signaling by H2S is proposed to occur via persulfidation, a posttranslational modification of cysteine residues (RSH) to persulfides (RSSH). Persulfidation provides a framework for understanding the physiological and pharmacological effects of H2S. Due to the inherent instability of persulfides, their chemistry is understudied. In this review, we discuss the biologically relevant chemistry of H2S and the enzymatic routes for its production and oxidation. We cover the chemical biology of persulfides and the chemical probes for detecting them. We conclude by discussing the roles ascribed to protein persulfidation in cell signaling pathways.

Chemical Biology of H2S Signaling through Persulfidation.

Adventitious roots are plant roots that form from any nonroot tissue and are produced both during normal development (crown roots on cereals and nodal roots on strawberry [Fragaria spp.]) and in response to stress conditions, such as flooding, nutrient deprivation, and wounding. They are important economically (for cuttings and food production), ecologically (environmental stress response), and for human existence (food production). To improve sustainable food production under environmentally extreme conditions, it is important to understand the adventitious root development of crops both in normal and stressed conditions. Therefore, understanding the regulation and physiology of adventitious root formation is critical for breeding programs. Recent work shows that different adventitious root types are regulated differently, and here, we propose clear definitions of these classes. We use three case studies to summarize the physiology of adventitious root development in response to flooding (case study 1), nutrient deficiency (case study 2), and wounding (case study 3).

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The Physiology of Adventitious Roots.

Abiotic stresses, such as low or high temperature, deficient or excessive water, high salinity, heavy metals, and ultraviolet radiation, are hostile to plant growth and development, leading to great crop yield penalty worldwide. It is getting imperative to equip crops with multistress tolerance to relieve the pressure of environmental changes and to meet the demand of population growth, as different abiotic stresses usually arise together in the field. The feasibility is raised as land plants actually have established more generalized defenses against abiotic stresses, including the cuticle outside plants, together with unsaturated fatty acids, reactive species scavengers, molecular chaperones, and compatible solutes inside cells. In stress response, they are orchestrated by a complex regulatory network involving upstream signaling molecules including stress hormones, reactive oxygen species, gasotransmitters, polyamines, phytochromes, and calcium, as well as downstream gene regulation factors, particularly transcription factors. In this review, we aimed at presenting an overview of these defensive systems and the regulatory network, with an eye to their practical potential via genetic engineering and/or exogenous application.

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Abiotic Stresses: General Defenses of Land Plants and Chances for Engineering Multistress Tolerance.

Hydrogen sulphide (H(2) S) has been proposed as the third gasotransmitter. In animal cells, H(2) S has been implicated in several physiological processes. H(2) S is endogenously synthesized in both animals and plants by enzymes with l-Cys desulphydrase activity in the conversion of l-Cys to H(2) S, pyruvate and ammonia. The participation of H(2) S in both stomatal movement regulation and abscisic acid (ABA)-dependent induction of stomatal closure was studied in epidermal strips of three plant species (Vicia faba, Arabidopsis thaliana and Impatiens walleriana). The effect of H(2) S on stomatal movement was contrasted with leaf relative water content (RWC) measurements of whole plants subjected to water stress. In this work we report that exogenous H(2) S induces stomatal closure and this effect is impaired by the ATP-binding cassette (ABC) transporter inhibitor glibenclamide; scavenging H(2) S or inhibition of the enzyme responsible for endogenous H(2) S synthesis partially blocks ABA-dependent stomatal closure; and H(2) S treatment increases RWC and protects plants against drought stress. Our results indicate that H(2) S induces stomatal closure and participates in ABA-dependent signalling, possibly through the regulation of ABC transporters in guard cells.

https://nph.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1469-8137.2010.03465.x

Hydrogen sulphide, a novel gasotransmitter involved in guard cell signalling

In this report, we demonstrate that sodium hydrosulfide (NaHS), a hydrogen sulfide (H(2)S) donor, promoted adventitious root formation mediated by auxin and nitric oxide (NO). Application of the H(2)S donor to seedling cuttings of sweet potato (Ipomoea batatas L.) promoted the number and length of adventitious roots in a dose-dependent manner. It was also verified that H(2)S or HS(-) rather than other sulfur-containing components derived from NaHS could be attributed to the stimulation of adventitious root formation. A rapid increase in endogenous H(2)S, indole acetic acid (IAA) and NO were sequentially observed in shoot tips of sweet potato seedlings treated with HaHS. Further investigation showed that H(2)S-mediated root formation was alleviated by N-1-naphthylphthalamic acid (NPA), an IAA transport inhibitor, and 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO), an NO scavenger. Similar phenomena in H(2)S donor-dependent root organogenesis were observed in both excised willow (Salix matsudana var. tortuosa Vilm) shoots and soybean (Glycine max L.) seedlings. These results indicated that the process of H(2)S-induced adventitious root formation was likely mediated by IAA and NO, and that H(2)S acts upstream of IAA and NO signal transduction pathways.

Hydrogen Sulfide Promotes Root Organogenesis in Ipomoea batatas, Salix matsudana and Glycine max

In this paper, effect of NaHS, a hydrogen sulfide (H2S) donor on chlorophyll and antioxidant metabolism in seedling leaves of sweetpotato under osmotic stress was investigated. With the enhancement of osmotic stress, which was mimicked by PEG-6000, chlorophyll in seedling leaves of sweetpotato (Ipomoea batatas) decreased dramatically. At 15% PEG (w/v), chlorophyll concentration reached only 50% compared with that of the controls. The osmotic-induced decrease in chlorophyll concentration could be alleviated by spraying exogenous H2S donor, NaHS in a dose-dependent manner, while little visible symptoms were observed in leaves sprayed with NaHS under control conditions. It was also shown that H2S or HS− rather than other sulfur-containing components derived from NaHS contributed to the protective role against chlorophyll degradation during osmotic stress. Further studies showed that NaHS spraying dramatically promoted the activities of superoxide dismutase, catalase, ascorbate peroxidase and decreased that of lipoxygenase and the concentrations of hydrogen peroxide (H2O2) and malondialdehyde. In addition, concentrations of endogenous H2S in NaHS-sprayed seedlings were higher than that in water-spraying control under osmotic stress. These data indicated that H2S plays a protective role in sweetpotato seedlings during osmotic stress.

Hydrogen sulfide counteracts chlorophyll loss in sweetpotato seedling leaves and alleviates oxidative damage against osmotic stress

The invention discloses a new application of sodium bisulfide (hydrogen sulfide donor) in promoting the storage and preservation of fruits and vegetables, i.e. an application of the sodium bisulfide (hydrogen sulfide donor) as fresh cut fruit-vegetable fresh-keeping agent. The sodium bisulfide (hydrogen sulfide donor) has a fresh-keeping effect on fresh cut vegetables such as broccoli, asparagus lettuce, lotus root, yam, pumpkin, sweet potato and potato and the like, and fresh cut fruits such as apple, pear, Chinese goosebeery, tomato, Hami melon and peach and the like. The sodium bisulfide can notably delay the wilting, dehydration, ripening, aging and mildewing of fresh cut fruits and vegetables, keep the quality characteristics of picked fruits and vegetables and prolong the storage periods and shelf lives of picked fresh cut fruits and vegetables by 0.5 to 12 days. The fresh-keeping agent can be used for keeping freshing on a variety of the picked fresh cut fruits and vegetables.

New application of sodium bisulfide as hydrogen sulfide donor in promoting storage and preservation of fruits and vegetables

Food spoilage leads to food wastage, human morbidity and mortality. This food preservation takes advantage of use of Hydrogen Sulfide without or with Hydrogen or Helium into an environment where food is stored. The method delays food ripening, food spoilage, food decay and is safe, and preserves the natural characteristics of food, including color, flavor, aroma and texture. Hydrogen Sulfide treatment maintains higher activities of catalase, guaiacol peroxidase, ascorbate peroxidase, glutathione reductase and lower activities of lipoxygenase relative to un-treated controls. Hydrogen Sulfide also reduces malondialdehyde, Hydrogen peroxide, and superoxide anion to levels below those in control fruits during storage. Hydrogen and Helium are administered as gas and Hydrogen Sulfide is administered as a gas, liquid, or a Hydrogen Sulfide donor, within a closed environment or by providing Hydrogen Sulfide within the item. This also includes enhancement of innate endogenous Hydrogen Sulfide-Hydrogen production in the organisms including plants.

Jun Tang

Papers

Hydrogen Sulfide Promotes Root Organogenesis in Ipomoea batatas, Salix matsudana and Glycine max

Hydrogen sulfide counteracts chlorophyll loss in sweetpotato seedling leaves and alleviates oxidative damage against osmotic stress

New application of sodium bisulfide as hydrogen sulfide donor in promoting storage and preservation of fruits and vegetables

A process of food preservation with hydrogen sulfide