Metabolic responses to sulfur dioxide in grapevine (Vitis vinifera L.): photosynthetic tissues and berries

A diel multi-tissue genome-scale metabolic model of Vitis vinifera

Vitis vinifera, also known as grapevine, is widely cultivated and commercialized, particularly to produce wine. As wine quality is directly linked to fruit quality, studying grapevine metabolism is important to understand the processes underlying grape composition. Genome-scale metabolic models (GSMMs) have been used for the study of plant metabolism and advances have been made, allowing the integration of omics datasets with GSMMs. On the other hand, Machine learning (ML) has been used to analyze and integrate omics data, and while the combination of ML with GSMMs has shown promising results, it is still scarcely used to study plants. Here, the first GSSM of V. vinifera was reconstructed and validated, comprising 7199 genes, 5399 reactions, and 5141 metabolites across 8 compartments. Tissue-specific models for the stem, leaf, and berry of the Cabernet Sauvignon cultivar were generated from the original model, through the integration of RNA-Seq data. These models have been merged into diel multi-tissue models to study the interactions between tissues at light and dark phases. The potential of combining ML with GSMMs was explored by using ML to analyze the fluxomics data generated by green and mature grape GSMMs and provide insights regarding the metabolism of grapes at different developmental stages. Therefore, the models developed in this work are useful tools to explore different aspects of grapevine metabolism and understand the factors influencing grape quality.

Cytosolic acidification and oxidation are the toxic mechanisms of SO2 in Arabidopsis guard cells

SO2/H2SO3 can damage plants. However, its toxic mechanism has still been controversial. Two models have been proposed, cytosolic acidification model and cellular oxidation model. Here, we assessed the toxic mechanism of H2SO3 in three cell types of Arabidopsis thaliana, mesophyll cells, guard cells (GCs), and petal cells. The sensitivity of GCs of Chloride channel a (CLCa)-knockout mutants to H2SO3 was significantly lower than those of wildtype plants. Expression of other CLC genes in mesophyll cells and petal cells were different from GCs. Treatment with antioxidant, disodium 4,5-dihydroxy-1,3-benzenedisulfonate (tiron), increased the median lethal concentration (LC50) of H2SO3 in GCs indicating the involvement of cellular oxidation, while the effect was negligible in mesophyll cells and petal cells. These results indicate that there are two toxic mechanisms of SO2 to Arabidopsis cells: cytosolic acidification and cellular oxidation, and the toxic mechanism may vary among cell types.

Comprehensive review: Effects of climate change and greenhouse gases emission relevance to environmental stress on horticultural crops and management

Global climate change exerts a significant impact on sustainable horticultural crop production and quality. Rising Global temperatures have compelled the agricultural community to adjust planting and harvesting schedules, often necessitating earlier crop cultivation. Notably, climate change introduces a suite of ominous factors, such as greenhouse gas emissions (CGHs), including elevated temperature, increased carbon dioxide (CO2) concentrations, nitrous oxide (N2O) and methane (CH4) ozone depletion (O3), and deforestation, all of which intensify environmental stresses on crops. Consequently, climate change stands poised to adversely affect crop yields and livestock production. Therefore, the primary objective of the review article is to furnish a comprehensive overview of the multifaceted factors influencing horticulture production, encompassing fruits, vegetables, and plantation crops with a particular emphasis on greenhouse gas emissions and environmental stressors such as high temperature, drought, salinity, and emission of CO2. Additionally, this review will explore the implementation of novel horticultural crop varieties and greenhouse technology that can contribute to mitigating the adverse impact of climate change on agricultural crops.

Novel insight into the role of sulfur dioxide in fruits and vegetables: Chemical interactions, biological activity, metabolism, applications, and safety

Sulfur dioxide (SO2) are a category of chemical compounds widely used as additives in food industry. So far, the use of SO2 in fruit and vegetable industry has been indispensable although its safety concerns have been controversial. This article comprehensively reviews the chemical interactions of SO2 with the components of fruit and vegetable products, elaborates its mechanism of antimicrobial, anti-browning, and antioxidation, discusses its roles in regulation of sulfur metabolism, reactive oxygen species (ROS)/redox, resistance induction, and quality maintenance in fruits and vegetables, summarizes the application technology of SO2 and its safety in human (absorption, metabolism, toxicity, regulation), and emphasizes the intrinsic metabolism of SO2 and its consequences for the postharvest physiology and safety of fresh fruits and vegetables. In order to fully understand the benefits and risks of SO2, more research is needed to evaluate the molecular mechanisms of SO2 metabolism in the cells and tissues of fruits and vegetables, and to uncover the interaction mechanisms between SO2 and the components of fruits and vegetables as well as the efficacy and safety of bound SO2. This review has important guiding significance for adjusting an applicable definition of maximum residue limit of SO2 in food.

The detoxification of cellular sulfite in table grape under SO2 exposure: Quantitative evidence of sulfur absorption and assimilation patterns

Sulfur dioxide (SO₂) and its derivatives are known to be hazardous but their common application in food, especially the grape industry, is conditionally allowed. Potential hazards to consumers and the environment could occur upon the control-lost SO₂ during grape logistics and storage. Researchers have usually focused on the anti-pathogen role of SO₂ whereas limited efforts were conducted on the sulfur (S) absorption, assimilation patterns, and sulfite detoxification. In this study, short-term, room-temperature, and SO₂-stored grapes were investigated, whose S flux of various forms was quantified through an estimation model. Accordingly, the additional accumulated S (0.50-0.86%) in pulps from atmospheric SO₂ was considered mainly through rachis transport compared to across skin surfaces and the usage arrangement of the absorbed S was included. The first quantitative evidence of induced S assimilation under SO₂ was also provided, which challenged the previous knowledge. In addition, sulfite oxidase and reductase (SiO and SiR) played major roles in sulfite detoxification, being effectively stimulated at multiple levels. The induced S metabolism associated with enhanced reactive oxygen species (ROS) scavenging capacity and alleviated senescence contributed to quality maintenance. Overall, these findings provide novel insights and are valuable supports for developing SO₂-controlling strategies to avoid potential hazards.

Microbial volatile organic compounds: Antifungal mechanisms, applications, and challenges

The fungal decay of fresh fruits and vegetables annually generates substantial global economic losses. The utilization of conventional synthetic fungicides is damaging to the environment and human health. Recently, the biological control of post-harvest fruit and vegetable diseases via antagonistic microorganisms has become an attractive possible substitution for synthetic fungicides. Numerous studies have confirmed the potential of volatile organic compounds (VOCs) for post-harvest disease management. Moreover, VOC emission is a predominant antifungal mechanism of antagonistic microorganisms. As such, it is of great significance to discuss and explore the antifungal mechanisms of microbial VOCs for commercial application. This review summarizes the main sources of microbial VOCs in the post-harvest treatment and control of fruit and vegetable diseases. Recent advances in the elucidation of antifungal VOC mechanisms are emphasized, and the applications of VOCs produced from antagonistic microorganisms are described. Finally, the current prospects and challenges associated with microbial VOCs are considered.

False positive effect of sulfur sources used in growing and processing of vine (Vitis Vinifera L.) leaves on the results of dithiocarbamate analysis based on carbon disulfide measurement

Vine leaves, which are produced fresh, brined or fermented from the leaves of Vitis Vinifera in Türkiye are an important food. Sulfur is used as a pesticide and sulfur compounds can be used as additives during the growing and processing of the vine leaves. These sulfur sources cause positive results on carbon disulfide (CS₂) measurements by GC-MS. Therefore, the main objective of the present study was to investigate the effects of residues of sulfur or sulfur compounds on dithiocarbamate analysis methods based on CS₂ measurement. For this, vine leaves were produced by controlled agricultural production and processed as brine under controlled conditions. The sulfur dioxide (SO₂) and dithiocarbamate analysis were carried out on the vine leave obtained by applying sulfur spraying in agricultural treatments and brined vine leaves produced by adding sodium metabisulfite (SM), and control samples of each stage. SO₂ was not detected in any of the samples in this study. SO₂ residues did not occur in the vine leaves as a result of the sulfur spraying application and therefore did not have a false positive effect on dithiocarbamate analysis. However, approximately 0.15 mg kg^-1 false positive dithiocarbamate was detected, which is thought to originate from natural sulfur in the vine leaves. The effect of SM, which was used in low concentration in the production of brined vine leaves, on dithiocarbamate results was limited. Even if SM was not used, the total false positive dithiocarbamate result in the brined vine leaves production process was approximately determined as 0.20 mg kg^-1. This study showed that the dithiocarbamates analysis method based on CS₂ measurement may lead to false positive results in brined vine leaves since sulfur compounds are found naturally in vine leaves.

Dynamics of plant responses to combinations of air pollutants

The focus of this review is on how plants respond to combinations of multiple air pollutants. Global pollution trends, plant physiological responses and ecological perspectives in natural and agricultural systems are all discussed. In particular, we highlight the importance of studying sequential or simultaneous exposure of plants to pollutants, rather than exposure to individual pollutants in isolation, and explore how these responses may interfere with the way plants interact with their biotic community. Air pollutants can alter the normal physiology and metabolic functioning of plants. Here we describe how the phenotypic and molecular changes in response to multiple pollutants can differ compared to those elicited by single pollutants, and how different responses have been observed between plants in the field and in controlled laboratory conditions and between trees and crop plants. From an ecological perspective, we discuss how air pollution can result in greater susceptibility to biotic stressors and in direct or indirect effects on interactions with organisms that occupy higher trophic levels. Finally, we provide an overview of the potential uses of plants to mitigate air pollution, exploring the feasibility for pollution removal via the processes of bio-accumulation and phytoremediation. We conclude by proposing some new directions for future research in the field.

The mechanism of SO2 -induced stomatal closure differs from O3 and CO2 responses and is mediated by nonapoptotic cell death in guard cells

Plants closing stomata in the presence of harmful gases is believed to be a stress avoidance mechanism. SO₂ , one of the major airborne pollutants, has long been reported to induce stomatal closure, yet the mechanism remains unknown. Little is known about the stomatal response to airborne pollutants besides O₃ . SLOW ANION CHANNEL-ASSOCIATED 1 (SLAC1) and OPEN STOMATA 1 (OST1) were identified as genes mediating O₃ -induced closure. SLAC1 and OST1 are also known to mediate stomatal closure in response to CO₂ , together with RESPIRATORY BURST OXIDASE HOMOLOGs (RBOHs). The overlaying roles of these genes in response to O₃ and CO₂ suggested that plants share their molecular regulators for airborne stimuli. Here, we investigated and compared stomatal closure event induced by a wide concentration range of SO₂ in Arabidopsis through molecular genetic approaches. O₃ - and CO₂ -insensitive stomata mutants did not show significant differences from the wild type in stomatal sensitivity, guard cell viability, and chlorophyll content revealing that SO₂ -induced closure is not regulated by the same molecular mechanisms as for O₃ and CO₂ . Nonapoptotic cell death is shown as the reason for SO₂ -induced closure, which proposed the closure as a physicochemical process resulted from SO₂ distress, instead of a biological protection mechanism.

Antifungal activity of Bignoniaceae plants on Aspergillus carbonarius and Aspergillus niger

Twenty four extracts from Bignoniaceae plants of northwest Argentina were tested for antifungal activity against Aspergillus species responsible of the grape black rot. Stems and leaves of Amphilophium cynanchoides, Macfadyena cynanchoides, Tecoma stans and Jacaranda mimosifolia were separately extracted with solvents of increasing polarity to obtain the dichloromethane (fCH₂Cl₂), ethyl acetate (fEtOAc) and methanol extracts (fMeOH). The fCH₂Cl₂ from stem of M. cynanchoides had the lowest IC₅₀ (1.0-1.2 mg/mL) and MID values (0.6-1.2 mg) and the highest ID values (5.0-6.8 mm) on A. niger and A. carbonarius. The main contributors of the antifungal activity of fCH₂Cl₂ were identified as lapachol (MIC = 0.25-1.00 mg/ml) and 1-hydroxy-4-methylanthraquinone (MIC = 0.0625-0.125 mg/mL). These compounds synergized the antifungal activity of sodium metabisulfite and showed an additive effect in mixtures with propiconazol. They might be used as additives of commercial antifungals to protect grapes against A. niger and A. carbonarius.

Sulfur fumigation reducing systemic exposure of ginsenosides and weakening immunomodulatory activity of ginseng

ETHNOPHARMACOLOGICAL RELEVANCE

Ginseng (Ginseng Radix et Rhizoma) is used worldwide for its miracle tonic effects, especially for its immunomodulatory activities. Sulfur fumigation, a fast and convenient method to prevent pesticidal and bacterial contamination in the food industry, has been recently employed during post-harvest processing of ginseng. Our previous studies demonstrated that sulfur fumigation significantly altered the chemical profile of the bioactive ingredients in ginseng. However, the effects of sulfur fumigation on the pharmacokinetics and bioactivities of ginseng remain unknown.

AIM OF THE STUDY

To examine the effects of sulfur fumigation on the pharmacokinetics and immunomodulatory activities of ginseng.

MATERIALS AND METHODS

For pharmacokinetic studies, male Sprague-Dawley rats exposed to single/multiple dosages of non-fumigated ginseng (NFG) and sulfur fumigated ginseng (SFG) were investigated using HPLC-MS/MS analysis. For bioactivity studies, male ICR mice were used to compare the immunomodulatory effects of NFG or SFG under both normal and cyclophosphamide (CY)-induced immunocompromised conditions using white blood cell counts, serum cytokine levels, and spleen and thymus weight indices.

RESULTS

Sulfur fumigation significantly reduced the contents of the bioactive ginsenosides in ginseng, which resulted in drastically low systemic exposure of ginsenosides in SFG-treatment group compared to NFG-treatment group. This observation was consistent with the bioactivities obtained in NFG- and SFG-treatment groups. The bioactivity studies also demonstrated the immunomodulatory effects of NFG but not SFG in the CY-induced immunosuppressed mice.

CONCLUSION

Sulfur fumigation significantly reduced contents of bioactive ginsenosides in ginseng, leading to dramatic decrease in the systemic exposure of these ginsenosides in the body and detrimental reduction of immunomodulatory effects of ginseng. Our results provided scientific evidences and laid a solid foundation for the needs of thorough evaluation of the significant impact of sulfur fumigation on ginseng and other medicinal herbs.

Fungal Endophytes as a Metabolic Fine-Tuning Regulator for Wine Grape

Endophytes proved to exert multiple effects on host plants, including growth promotion, stress resistance. However, whether endophytes have a role in metabolites shaping of grape has not been fully understood. Eight endophytic fungal strains which originally isolated from grapevines were re-inoculated to field-grown grapevines in this study, and their effects on both leaves and berries of grapevines at maturity stage were assessed, with special focused on secondary metabolites and antioxidant activities. High-density inoculation of all these endophytic fungal strains modified the physio-chemical status of grapevine to different degrees. Fungal inoculations promoted the content of reducing sugar (RS), total flavonoids (TF), total phenols (TPh), trans-resveratrol (Res) and activities of phenylalanine ammonia-lyase (PAL), in both leaves and berries of grapevine. Inoculation of endophytic fungal strains, CXB-11 (Nigrospora sp.) and CXC-13 (Fusarium sp.) conferred greater promotion effects in grape metabolic re-shaping, compared to other used fungal strains. Additionally, inoculation of different strains of fungal endophytes led to establish different metabolites patterns of wine grape. The work implies the possibility of using endophytic fungi as fine-tuning regulator to shape the quality and character of wine grape.

Suitability of Tillandsia usneoides and Aechmea fasciata for biomonitoring toxic elements under tropical seasonal climate

Aechmea fasciata was evaluated for the first time as a biomonitor of toxic elements, in comparison to the biomonitoring capacity of Tillandsia usneoides, a well-established biomonitor bromeliad species. Plants of both species were exposed to air pollutants from industrial, urban, and agricultural sources, under the tropical seasonal climate, from June/2011 to April/2013, in five sites of São Paulo State, Brazil, for 8 consecutive exposure periods of 12 weeks each. The levels of essential and non-essential elements, including trace metals, were quantified at the end of each exposure. T. usneoides and A. fasciata indicated N, Fe, Zn, Co, Cr, and V as air contaminants in the studied sites, during wet and dry seasons and both species were recommended for qualitative biomonitoring. Concentration levels of N, Ca, S, Fe, Zn, Cu, B, Co, and Ni were significantly higher in T. usneoides than in A. fasciata. However, A. fasciata showed a higher effective retention capacity of Ni, Pb, V, Cu, Fe, Cr, and Co during field exposure, as indicated by the estimate of enrichment factor relative to basal concentrations. This species is more suitable for detecting the atmospheric pollution level of those metals than the T. usneoides. Both species indicated adequately the seasonal differences in the pollution levels of several elements, but T. usneoides presented higher ability for biomonitoring the spatial variations and for indicating more properly the sources of each element in the studied region than the A. fasciata.