Crop plants are subjected to multiple abiotic stresses during their lifespan that greatly reduce productivity and threaten global food security. Recent research suggests that plants can be primed by ...chemical compounds to better tolerate different abiotic stresses. Chemical priming is a promising field in plant stress physiology and crop stress management. We review here promising chemical agents such as sodium nitroprusside, hydrogen peroxide, sodium hydrosulfide, melatonin, and polyamines that can potentially confer enhanced tolerance when plants are exposed to multiple abiotic stresses. The challenges and opportunities of chemical priming are addressed, with the aim to boost future research towards effective application in crop stress management.
Plant priming using chemical agents such as sodium nitroprusside, hydrogen peroxide, sodium hydrosulfide, melatonin, and polyamines enhances plant tolerance to different abiotic stresses, improving cellular homeostasis and plant growth under stress conditions.
Commonly employed chemical priming agents share components in their modes of action.
When used against different abiotic stresses, the modes of action of a chemical agent show similarities but also distinct specificities.
Chemical priming through using selected chemical agents is a promising tool against various individual or combined abiotic stresses.
The efficiency of chemical priming depends highly on the mode of application.
Considering titanium dioxide nanoparticles (TiO
NPs) role in plant growth and especially in plant tolerance against abiotic stress, a greenhouse experiment was carried out to evaluate TiO
NPs effects ...(0, 50, 100 and 200 mg L
) on agronomic traits of Moldavian balm (Dracocephalum moldavica L.) plants grown under different salinity levels (0, 50 and 100 mM NaCl). Results demonstrated that all agronomic traits were negatively affected under all salinity levels but application of 100 mg L
TiO
NPs mitigated these negative effects. TiO
NPs application on Moldavian balm grown under salt stress conditions improved all agronomic traits and increased antioxidant enzyme activity compared with plants grown under salinity without TiO
NP treatment. The application of TiO
NPs significantly lowered H
O
concentration. In addition, highest essential oil content (1.19%) was obtained in 100 mg L
TiO
NP-treated plants under control conditions. Comprehensive GC/MS analysis of essential oils showed that geranial, z-citral, geranyl acetate and geraniol were the dominant essential oil components. The highest amounts for geranial, geraniol and z-citral were obtained in 100 mg L
TiO
NP-treated plants under control conditions. In conclusion, application of 100 mg L
TiO
NPs could significantly ameliorate the salinity effects in Moldavian balm.
Hydrogen sulfide (H
S), an endogenous gaseous molecule, is considered as a signaling agent, in parallel with other low molecular weight reactive substances, mainly hydrogen peroxide (H
O
) and nitric ...oxide (NO), in various plant systems. New studies are now revealing that the postharvest application of H
S, through H
S donors such as sodium hydrosulfide (NaSH) or sodium sulfide (Na
S), can inhibit fruit ripening and senescence programs in numerous fruits. We discuss here current knowledge on the impact of H
S in postharvest physiology of several climacteric and non-climacteric fruits such as banana, apple, pear, kiwifruit, strawberry, mulberry fruit, and grape. Although there is still a considerable lack of studies establishing the mechanisms by which H
S signaling is linked to fruit metabolism, we highlight several candidate mechanisms, including a putative cross-talk between H
S and ethylene, reactive oxygen and nitrogen species, oxidative/nitrosative stress signaling, sulfate metabolism, and post-translational modification of protein cysteine residues (
sulfhydration) as being functional in this H
S postharvest action. Understanding H
S metabolism and signaling during postharvest storage and the interplay with other key player molecules would therefore provide new, improved strategies for better fruit postharvest storage. To achieve this understanding, postharvest fruit physiology research will need to focus increasingly on the spatial interaction between H
S and ethylene perception as well as on the interplay between
-sulfhydration/desulfhydration and
-nitrosylation/denitrosylation under several postharvest conditions.
The use of reclaimed wastewater (RWW) for the irrigation of crops may result in the continuous exposure of the agricultural environment to antibiotics, antibiotic resistant bacteria (ARB) and ...antibiotic resistance genes (ARGs). In recent years, certain evidence indicate that antibiotics and resistance genes may become disseminated in agricultural soils as a result of the amendment with manure and biosolids and irrigation with RWW. Antibiotic residues and other contaminants may undergo sorption/desorption and transformation processes (both biotic and abiotic), and have the potential to affect the soil microbiota. Antibiotics found in the soil pore water (bioavailable fraction) as a result of RWW irrigation may be taken up by crop plants, bioaccumulate within plant tissues and subsequently enter the food webs; potentially resulting in detrimental public health implications. It can be also hypothesized that ARGs can spread among soil and plant-associated bacteria, a fact that may have serious human health implications. The majority of studies dealing with these environmental and social challenges related with the use of RWW for irrigation were conducted under laboratory or using, somehow, controlled conditions. This critical review discusses the state of the art on the fate of antibiotics, ARB and ARGs in agricultural environment where RWW is applied for irrigation. The implications associated with the uptake of antibiotics by plants (uptake mechanisms) and the potential risks to public health are highlighted. Additionally, knowledge gaps as well as challenges and opportunities are addressed, with the aim of boosting future research towards an enhanced understanding of the fate and implications of these contaminants of emerging concern in the agricultural environment. These are key issues in a world where the increasing water scarcity and the continuous appeal of circular economy demand answers for a long-term safe use of RWW for irrigation.
•The fate of antibiotics, ARB&ARGs in reclaimed WW-irrigated sites is discussed.•Antibiotic may undergo sorption/desorption and transformation processes in soil.•Antibiotics may be taken up and bioaccumulated within reclaimed WW-irrigated plants.•ARGs spread in reclaimed WW-irrigated sites may pose serious human health effects.•Antibiotics may exert phytotoxic effects to reclaimed WW-irrigated plants.
During the last years, a great effort has been dedicated at the development and employment of diverse approaches for achieving more stress‐tolerant and climate‐flexible crops and sustainable yield ...increases to meet the food and energy demands of the future. The ongoing climate change is in fact leading to more frequent extreme events with a negative impact on food production, such as increased temperatures, drought, and soil salinization as well as invasive arthropod pests and diseases. In this review, diverse “green strategies” (e.g., chemical priming, root‐associated microorganisms), and advanced technologies (e.g., genome editing, high‐throughput phenotyping) are described on the basis of the most recent research evidence. Particularly, attention has been focused on the potential use in a context of sustainable and climate‐smart agriculture (the so called “next agriculture generation”) to improve plant tolerance and resilience to abiotic and biotic stresses. In addition, the gap between the results obtained in controlled experiments and those from application of these technologies in real field conditions (lab to field step) is also discussed.
Sodium nitroprusside (SNP) and hydrogen peroxide (H2O2), as priming agents, have the well‐recorded property to increase plant tolerance against a range of different abiotic stresses such as salinity. ...In this regard, the present study was conducted to evaluate the effect of different levels of SNP (100 and 200 µM) and H2O2 (2.5 and 5 mM) as well as their combinations under salt stress (0 and 50 mM NaCl) on key physiological and biochemical attributes of the economically important aromatic plant basil (Ocimum basilicum L.) grown under hydroponic culture. Results revealed that morphological parameters such as plant height, root length, leaf fresh and dry weights (FW and DW) were significantly decreased by salinity stress, while SNP and H2O2 treatments, alone or combined, increased FW and DW thus enhancing plant tolerance to salt stress. Furthermore, 200 µM SNP + 2.5 mM H2O2 appeared to be the most effective treatment by causing significant increase in chlorophyll a and b, anthocyanin content and guaiacol peroxidase and ascorbate peroxidase enzymes activities under saline condition. In addition, analytical measurements showed that essential oil profile (concentration of main components) under salt stress was mostly affected by SNP and H2O2 treatments. The highest increase was observed for methyl chavicol (43.09–69.91%), linalool (4.8–17.9%), cadinol (1.5–3.2%) and epi‐α‐cadinol (0.18–10.75%) compounds. In conclusion, current findings demonstrated a positive crosstalk between SNP and H2O2 toward improved basil plant tolerance to salt stress, linked with regulation of essential oil composition.
Global climate change and associated adverse abiotic stress conditions, such as drought, salinity, heavy metals, waterlogging, extreme temperatures, oxygen deprivation, etc., greatly influence plant ...growth and development, ultimately affecting crop yield and quality, as well as agricultural sustainability in general. Plant cells produce oxygen radicals and their derivatives, so-called reactive oxygen species (ROS), during various processes associated with abiotic stress. Moreover, the generation of ROS is a fundamental process in higher plants and employs to transmit cellular signaling information in response to the changing environmental conditions. One of the most crucial consequences of abiotic stress is the disturbance of the equilibrium between the generation of ROS and antioxidant defense systems triggering the excessive accumulation of ROS and inducing oxidative stress in plants. Notably, the equilibrium between the detoxification and generation of ROS is maintained by both enzymatic and nonenzymatic antioxidant defense systems under harsh environmental stresses. Although this field of research has attracted massive interest, it largely remains unexplored, and our understanding of ROS signaling remains poorly understood. In this review, we have documented the recent advancement illustrating the harmful effects of ROS, antioxidant defense system involved in ROS detoxification under different abiotic stresses, and molecular cross-talk with other important signal molecules such as reactive nitrogen, sulfur, and carbonyl species. In addition, state-of-the-art molecular approaches of ROS-mediated improvement in plant antioxidant defense during the acclimation process against abiotic stresses have also been discussed.
Reactive oxygen and nitrogen species are involved in a plethora of cellular responses in plants; however, our knowledge on the outcomes of oxidative and nitrosative signaling is still unclear. To ...better understand how oxidative and nitrosative signals are integrated to regulate cellular adjustments to external conditions, local and systemic responses were investigated in the roots and leaves of sour orange plants (Citrus aurantium L.) after root treatment with hydrogen peroxide (H2O2) or sodium nitroprusside (a nitric oxide donor), followed by NaCl stress for 8 days. Phenotypic and physiological data showed that pre‐exposure to these treatments induced an acclimation to subsequent salinity stress that was accompanied by both local and systemic H2O2 and nitric oxide (NO) accumulation. Combined histochemical and fluorescent probe approaches showed the existence of a vascular‐driven long‐distance reactive oxygen species and NO signaling pathway. Transcriptional analysis of genes diagnostic for H2O2 and NO signaling just after treatments or after 8 days of salt stress revealed tissue‐ and time‐specific mechanisms controlling internal H2O2 and NO homeostasis. Furthermore, evidence is presented showing that protein carbonylation, nitration and S‐nitrosylation are involved in acclimation to salinity stress. In addition, this work enabled characterization of potential carbonylated, nitrated and nitrosylated proteins with distinct or overlapping signatures. This work provides a framework to better understand the oxidative and nitrosative priming network in citrus plants subjected to salinity conditions.
The interplay among polyamines (PAs) and reactive oxygen and nitrogen species (RNS and ROS) is emerging as a key issue in plant responses to salinity. To address this question, we analysed the impact ...of exogenous PAs putrescine (Put), spermidine (Spd) and spermine (Spm) on the oxidative and nitrosative status in citrus plants exposed to salinity. PAs partially reversed the NaCl‐induced phenotypic and physiological disturbances. The expression of PA biosynthesis (ADC, SAMDC, SPDS and SPMS) and catabolism (DAO and PAO) genes was systematically up‐regulated by PAs. In addition, PAs altered the oxidative status in salt‐stressed plants as inferred by changes in ROS production and redox status accompanied by regulation of transcript expression and activities of various antioxidant enzymes. Furthermore, NaCl‐induced up‐regulation of NO‐associated genes, such as NR, NADde, NOS‐like and AOX, along with S‐nitrosoglutathione reductase and nitrate reductase activities, was partially restored by PAs. Protein carbonylation and tyrosine nitration are depressed by specific PAs whereas protein S‐nitrosylation was elicited by all PAs. Furthermore, we identified 271 S‐nitrosylated proteins that were commonly or preferentially targeted by salinity and individual PAs. This work helps improve our knowledge on the plant's response to environmental challenge.
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