Enhancing salinity tolerance in cucumber through Selenium biofortification and grafting.

BACKGROUND: Salinity stress is a major limiting factor for plant growth, particularly in arid and semi-arid environments. To mitigate the detrimental effects of salinity stress on vegetable production, selenium (Se) biofortification and grafting onto tolerant rootstocks have emerged as effective and sustainable cultivation practices. This study aimed to investigate the combined effects of Se biofortification and grafting onto tolerant rootstock on the yield of cucumber grown under salinity stress greenhouse conditions. The experiment followed a completely randomized factorial design with three factors: salinity level (0, 50, and 100 mM of NaCl), foliar Se application (0, 5, and 10 mg L-1 of sodium selenate) and grafting (grafted and non-grafted plants) using pumpkin (Cucurbita maxima) as the rootstock. Each treatment was triplicated. RESULTS: The results of this study showed that Se biofortification and grafting significantly enhanced salinity tolerance in grafted cucumbers, leading to increased yield and growth. Moreover, under salinity stress conditions, Se-Biofortified plants exhibited increased leaf relative water content (RWC), proline, total soluble sugars, protein, phenol, flavonoids, and antioxidant enzymes. These findings indicate that Se contributes to the stabilization of cucumber cell membrane and the reduction of ion leakage by promoting the synthesis of protective compounds and enhancing antioxidant enzyme activity. Moreover, grafting onto pumpkin resulted in increased salinity tolerance of cucumber through reduced Na uptake and translocation to the scion. CONCLUSION: In conclusion, the results highlight the effectiveness of Se biofortification and grafting onto pumpkin in improving cucumber salinity tolerance. A sodium selenate concentration of 10 mg L-1 is suggested to enhance the salinity tolerance of grafted cucumbers. These findings provide valuable insights for the development of sustainable cultivation practices to mitigate the adverse impact of salinity stress on cucumber production in challenging environments.

Impact of two Erwinia sp. on the response of diverse Pisum sativum genotypes under salt stress.

Currently, salinization is impacting more than 50% of arable land, posing a significant challenge to agriculture globally. Salt causes osmotic and ionic stress, determining cell dehydration, ion homeostasis, and metabolic process alteration, thus negatively influencing plant development. A promising sustainable approach to improve plant tolerance to salinity is the use of plant growth-promoting bacteria (PGPB). This work aimed to characterize two bacterial strains, that have been isolated from pea root nodules, initially called PG1 and PG2, and assess their impact on growth, physiological, biochemical, and molecular parameters in three pea genotypes (Merveille de Kelvedon, Lincoln, Meraviglia d'Italia) under salinity. Bacterial strains were molecularly identified, and characterized by in vitro assays to evaluate the plant growth promoting abilities. Both strains were identified as Erwinia sp., demonstrating in vitro biosynthesis of IAA, ACC deaminase activity, as well as the capacity to grow in presence of NaCl and PEG. Considering the inoculation of plants, pea biometric parameters were unaffected by the presence of the bacteria, independently by the considered genotype. Conversely, the three pea genotypes differed in the regulation of antioxidant genes coding for catalase (PsCAT) and superoxide dismutase (PsSOD). The highest proline levels (212.88 µmol g-1) were detected in salt-stressed Lincoln plants inoculated with PG1, along with the up-regulation of PsSOD and PsCAT. Conversely, PG2 inoculation resulted in the lowest proline levels that were observed in Lincoln and Meraviglia d'Italia (35.39 and 23.67 µmol g-1, respectively). Overall, this study highlights the potential of these two strains as beneficial plant growth-promoting bacteria in saline environments, showing that their inoculation modulates responses in pea plants, affecting antioxidant gene expression and proline accumulation. Supplementary Information: The online version contains supplementary material available at 10.1007/s12298-024-01419-8.

Foliar application of chitosan-putrescine nanoparticles (CTS-Put NPs) alleviates cadmium toxicity in grapevine (Vitis vinifera L.) cv. Sultana: modulation of antioxidant and photosynthetic status.

BACKGROUND: Cadmium (Cd) stress displays critical damage to the plant growth and health. Uptake and accumulation of Cd in plant tissues cause detrimental effects on crop productivity and ultimately impose threats to human beings. For this reason, a quite number of attempts have been made to buffer the adverse effects or to reduce the uptake of Cd. Of those strategies, the application of functionalized nanoparticles has lately attracted increasing attention. Former reports clearly noted that putrescine (Put) displayed promising effects on alleviating different stress conditions like Cd and similarly chitosan (CTS), as well as its nano form, demonstrated parallel properties in this regard besides acting as a carrier for many loads with different applications in the agriculture industry. Herein, we, for the first time, assayed the potential effects of nano-conjugate form of Put and CTS (CTS-Put NP) on grapevine (Vitis vinifera L.) cv. Sultana suffering from Cd stress. We hypothesized that their nano conjugate combination (CTS-Put NPs) could potentially enhance Put proficiency, above all at lower doses under stress conditions via CTS as a carrier for Put. In this regard, Put (50 mg L- 1), CTS (0.5%), Put 50 mg L- 1 + CTS 0.5%" and CTS-Put NPs (0.1 and 0.5%) were applied on grapevines under Cd-stress conditions (0 and 10 mg kg- 1). The interactive effects of CTS-Put NP were investigated through a series of physiological and biochemical assays. RESULTS: The findings of present study clearly revealed that CTS-Put NPs as optimal treatments alleviated adverse effects of Cd-stress condition by enhancing chlorophyll (chl) a, b, carotenoids, Fv/Fm, Y(II), proline, total phenolic compounds, anthocyanins, antioxidant enzymatic activities and decreasing Y (NO), leaf and root Cd content, EL, MDA and H2O2. CONCLUSIONS: In conclusion, CTS-Put NPs could be applied as a stress protection treatment on plants under diverse heavy metal toxicity conditions to promote plant health, potentially highlighting new avenues for sustainable crop production in the agricultural sector under the threat of climate change.

Biological activity and development of functional foods fortified with okra (Abelmoschus esculentus).

The Abelmoschus esculentus plant, better known as okra, is an interesting crop from a nutritional standpoint. The okra plant is native to the African region but can now be found throughout tropical and subtropical areas of the world. This plant, known for its healing abilities, has been used as a traditional medicine to treat several diseases and external ailments, such as wounds or boils. This article reviews the potential health benefits from okra consumption, as well as the bioactive compounds that are suggested to be responsible. Furthermore, the okra plant and its derivatives have been evaluated in the formulation and manufacture of new functional food products. The latest advances in this direction, which includes characterizing the technical properties of functional foods fortified with okra are also presented in this review. A series of bioactive compounds such as flavonoids and catechins have been found in the okra plant, which were associated with numerous biological properties observed in research studies that reported potential anti-diabetic, anti-cancer, anti-hypertensive, and antimicrobial effects, among others, as a result of their consumption. These potential health benefits contribute to the development of new and useful functional foods, with okra (or its derivatives) being used as the highlighted ingredient.

Postharvest chitosan-arginine nanoparticles application ameliorates chilling injury in plum fruit during cold storage by enhancing ROS scavenging system activity.

BACKGROUND: Plum (Prunus domestica L.) has a short shelf-life period due to its high respiration rate and is sensitive to low storage temperatures, which can lead to the appearance of chilling injury symptoms. In this investigation, we applied new coating treatments based on chitosan (CTS) and arginine (Arg) to plum fruit (cv. 'Stanley'). RESULTS: Fruit were treated with distilled water (control), Arg at 0.25 and 0.5 mM, CTS at 1% (w/v) or Arg-coated CTS nanoparticles (CTS-Arg NPs) at 0.5 and 1% (w/v), and then stored at 1 °C for days. The application of CTS-Arg NPs at 0.5% attenuated chilling injury, which was accompanied by accumulation of proline, reduced levels of electrolyte leakage and malondialdehyde, as well as suppressed the activity of polyphenol oxidase. Plums coated with CTS-Arg NPs (0.5%) showed higher accumulation of phenols, flavonoids and anthocyanins, due to the higher activity of phenylalanine ammonia-lyase, which in turn resulted in higher DPPH scavenging capacity. In addition, CTS-Arg NPs (0.5%) treatment delayed plum weight loss and retained fruit firmness and ascorbic acid content in comparison to control fruit. Furthermore, plums treated with CTS-Arg NPs exhibited lower H2O2 accumulation than control fruit due to higher activity of antioxidant enzymes, including CAT, POD, APX and SOD. CONCLUSIONS: The present findings show that CTS-Arg NPs (0.5%) were the most effective treatment in delaying chilling injury and prolonging the shelf life of plum fruit.

Exogenous melatonin increases salt tolerance in bitter melon by regulating ionic balance, antioxidant system and secondary metabolism-related genes.

BACKGROUND: Melatonin is a multi-functional molecule widely employed in order to mitigate abiotic stress factors, in general and salt stress in particular. Even though previous reports revealed that melatonin could exhibit roles in promoting seed germination and protecting plants during various developmental stages of several plant species under salt stress, no reports are available with respect to the regulatory acts of melatonin on the physiological and biochemical status as well as the expression levels of defense- and secondary metabolism-related related transcripts in bitter melon subjected to the salt stress. RESULTS: Herewith the present study, we performed a comprehensive analysis of the physiological and ion balance, antioxidant system, as well as transcript analysis of defense-related genes (WRKY1, SOS1, PM H+-ATPase, SKOR, Mc5PTase7, and SOAR1) and secondary metabolism-related gene expression (MAP30, α-MMC, polypeptide-P, and PAL) in salt-stressed bitter melon (Momordica charantia L.) plants in response to melatonin treatment. In this regard, different levels of melatonin (0, 75 and 150 µM) were applied to mitigate salinity stress (0, 50 and 100 mM NaCl) in bitter melon. Accordingly, present findings revealed that 100 mM salinity stress decreased growth and photosynthesis parameters (SPAD, Fv/Fo, Y(II)), RWC, and some nutrient elements (K+, Ca2+, and P), while it increased Y(NO), Y(NPQ), proline, Na+, Cl-, H2O2, MDA, antioxidant enzyme activity, and lead to the induction of the examined genes. However, prsiming with 150 µM melatonin increased SPAD, Fv/Fo, Y(II)), RWC, and K+, Ca2+, and P concentration while decreased Y(NO), Y(NPQ), Na+, Cl-, H2O2, and MDA under salt stress. In addition, the antioxidant system and gene expression levels were increased by melatonin (150 µM). CONCLUSIONS: Overall, it can be postulated that the application of melatonin (150 µM) has effective roles in alleviating the adverse impacts of salinity through critical modifications in plant metabolism.

Physiological and biochemical responses of strawberry crown and leaf tissues to freezing stress.

BACKGROUND: In northern Iran and other cold regions, winter freezing injury and resultant yield instability are major limitations to strawberry production. However, there is scarcity of information on the physiological and biochemical responses of strawberry cultivars to freezing stress. This study aimed to investigate the physiological and biochemical responses of strawberry cultivars (Tennessee Beauty, Blakemore, Kurdistan, Queen Elisa, Chandler, Krasnyy Bereg, and Yalova) to different freezing temperature treatments (- 5, - 10, - 15, - 20, and - 25 °C) under controlled conditions. RESULTS: All measured physiological and biochemical features were significantly affected by the interaction effect between low temperatures and cultivars. Tennessee Beauty showed the highest RWC at - 25 °C. The highest Fv/Fm was observed in Queen Elisa. Krasnyy Bereg had the least freezing injury (FI) in crown and leaf, while Yalova and Chandler showed the highest crown and leaf FI, respectively. At - 20 to - 25 °C, the highest carbohydrates contents of crown and leaf were noted in Blakemore and Krasnyy Bereg cultivars, respectively. The Yalova showed the highest protein content in both crown and leaf tissues at - 25 °C. The Tennessee Beauty and Blackmore cultivars showed the highest proline in crowns and leaves at - 15 °C, respectively. The highest ThioBarbituric Acid Reactive Substances (TBARS) contents in the crown and leaf were observed in Kurdistan and Queen Elisa, respectively. Queen Elisa and Krasnyy Bereg cultivars showed SOD and POD peaks in the crown at - 15 °C, respectively. CONCLUSION: Freezing stress was characterized by decreased Fv/Fm and RWC, and increased FI, TBARS, total carbohydrates, total proteins, proline content, and antioxidant enzyme activity. The extent of changes in above mentioned traits was cultivar dependent. FI and TBARS were the best traits among destructive parameters for evaluating freezing tolerance. Moreover, maximum quantum yield of PSII (Fv/Fm index), as non-destructive parameters, showed a significant efficiency in rapid assessment for screening of freezing tolerant strawberry cultivars. The cultivars Krasnyy Bereg, Queen Elisa, and Kurdistan were the most tolerant cultivars to freezing stress. These cultivars can be used as parents in breeding programs to develop new freezing tolerant cultivars.

Putrescine-functionalized carbon quantum dot (put-CQD) nanoparticles effectively prime grapevine (Vitis vinifera cv. 'Sultana') against salt stress.

BACKGROUND: Salinity is an important global problem with destructive impacts on plants leading to different biochemical and metabolic changes in plants through induced oxidative stress that disturbs metabolism, growth, performance and productivity of plants. Given that putrescine (Put) and carbon quantum dots (CQDs), individually, have promising effects in different plant processes, the idea of their combination in a nano-structure "Put-CQD" lead to its synthesis to evaluate the potential exertion of synergistic effects. The current study aimed to investigate the application of newly-synthesized nanoparticles (NPs) consisting of CQDs and Put in grapevine (Vitis vinifera cv. 'Sultana') under salinity stress conditions. For this purpose, Put, CQDs and Put-CQD NPs at 5 and 10 mg L- 1 concentrations were applied as chemical priming agents in 'Sultana' grapevine 48 h prior salinity stress imposition (0 and 100 mM NaCl). RESULTS: Salinity significantly decreased (P ≤ 0.05) morphological parameters, photosynthetic pigments, chlorophyll fluorescence parameters and membrane stability index. In addition, salinity enhanced MDA, H2O2, proline content and antioxidant enzyme activity. Results revealed that Put-CQD NPs, particularly at 10 mg L- 1 concentration, alleviated the destructive impacts of salinity stress by improving leaf fresh and dry weights, K+ content, photosynthetic pigments, chlorophyll fluorescence and SPAD parameters, proline content, total phenolics and antioxidant enzymatic activities (CAT, APX, GP and SOD), while decreasing Na+ content, EL, MDA and H2O2 levels. CONCLUSION: To conclude, Put-CQD NPs represent an innovative priming treatment that could be effectively applied on grapevine to improve plant performance under salinity stress conditions.

Protective effects of cerium oxide nanoparticles in grapevine (Vitis vinifera L.) cv. Flame Seedless under salt stress conditions.

High levels of soil salinity can cause substantial decline in growth and productivity of crops worldwide, thus representing a major threat to global agriculture. In recent years, engineered nanoparticles (NPs) have been deemed as a promising alternative in combating abiotic stress factors, such as salinity. In this context, the present study was designed to explore the potential of cerium oxide nanoparticles (CeO2NPs) in alleviating salt stress in grapevine (Vitis vinifera L. cv. Flame Seedless) cuttings. Specifically, the interaction between CeO2 NPs (25, 50 and 100 mg L-1) and salinity (25 and 75 mM NaCl) was evaluated by assaying an array of agronomic, physiological, analytical and biochemical parameters. Treatments with CeO2 NPs, in general, alleviated the adverse impacts of salt stress (75 mM NaCl) significantly improving relevant agronomic traits of grapevine. CeO2 NPs significantly ameliorated chlorophyll damage under high levels of salinity. Furthermore, the presence of CeO2 NPs attenuated salinity-induced damages in grapevine as indicated by lower levels of proline, MDA and EL; however, H2O2 content was not ameliorated by the presence of CeO2 NPs under salt stress. Additionally, salinity caused substantial increases in enzymatic activities of GP, APX and SOD, compared with control plants. Similar to stress conditions, all concentrations of CeO2 NPs triggered APX activity, while the highest concentration of CeO2 NPs significantly increased GP activity. However, CeO2 NPs did not significantly modify SOD activity. Considering mineral nutrient profile, salinity increased Na and Cl content as well as Na/K ratio, while it decreased K, P and Ca contents. Nevertheless, the presence of CeO2 NPs did not lead to significant alterations in Na, K and P content of salt-stressed plants. Taken together, current findings suggest that CeO2 NPs could be employed as promising salt-stress alleviating agents in grapevine.

Salt Stress Mitigation via the Foliar Application of Chitosan-Functionalized Selenium and Anatase Titanium Dioxide Nanoparticles in Stevia (Stevia rebaudiana Bertoni).

High salt levels are one of the significant and major limiting factors on crop yield and productivity. Out of the available attempts made against high salt levels, engineered nanoparticles (NPs) have been widely employed and considered as effective strategies in this regard. Of these NPs, titanium dioxide nanoparticles (TiO2 NPs) and selenium functionalized using chitosan nanoparticles (Cs-Se NPs) were applied for a quite number of plants, but their potential roles for alleviating the adverse effects of salinity on stevia remains unclear. Stevia (Stevia rebaudiana Bertoni) is one of the reputed medicinal plants due to their diterpenoid steviol glycosides (stevioside and rebaudioside A). For this reason, the current study was designed to investigate the potential of TiO2 NPs (0, 100 and 200 mg L-1) and Cs-Se NPs (0, 10 and 20 mg L-1) to alleviate salt stress (0, 50 and 100 mM NaCl) in stevia. The findings of the study revealed that salinity decreased the growth and photosynthetic traits but resulted in substantial cell damage through increasing H2O2 and MDA content, as well as electrolyte leakage (EL). However, the application of TiO2 NPs (100 mg L-1) and Cs-Se NPs (20 mg L-1) increased the growth, photosynthetic performance and activity of antioxidant enzymes, and decreased the contents of H2O2, MDA and EL under the saline conditions. In addition to the enhanced growth and physiological performance of the plant, the essential oil content was also increased with the treatments of TiO2 (100 mg L-1) and Cs-Se NPs (20 mg L-1). In addition, the tested NPs treatments increased the concentration of stevioside (in the non-saline condition and under salinity stress) and rebaudioside A (under the salinity conditions) in stevia plants. Overall, the current findings suggest that especially 100 mg L-1 TiO2 NPs and 20 mg L-1 Cs-Se could be considered as promising agents in combating high levels of salinity in the case of stevia.

Interaction between hydrogen peroxide and sodium nitroprusside following chemical priming of Ocimum basilicum L. against salt stress.

Sodium nitroprusside (SNP) and hydrogen peroxide (H2 O2 ), 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 H2 O2 (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 H2 O2 treatments, alone or combined, increased FW and DW thus enhancing plant tolerance to salt stress. Furthermore, 200 µM SNP + 2.5 mM H2 O2 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 H2 O2 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 H2 O2 toward improved basil plant tolerance to salt stress, linked with regulation of essential oil composition.

Phenylalanine Alleviates Postharvest Chilling Injury of Plum Fruit by Modulating Antioxidant System and Enhancing the Accumulation of Phenolic Compounds.

RESEARCH BACKGROUND: Low temperature storage causes chilling injury in plum (Prunus domestica L.) fruits. Consequently, any treatments with beneficial effects against these symptoms would achieve attention. For this purpose, phenylalanine treatments were applied on 'Stanley' plum fruits. The main purpose of the present study is to investigate the influence of the exogenous application of phenylalanine on fruit quality, chilling tolerance, and antioxidant capacity of 'Stanley' plums during cold storage. EXPERIMENTAL APPROACH: Phenylalanine at different concentrations was applied on 'Stanley' plums. Following phenylalanine application, plums were cold stored. Chilling injury, antioxidant capacity, electrolyte leakage, malondialdehyde, proline and internal contents of anthocyanin, flavonoids, phenols, ascorbic acid and some antioxidant enzymes were assessed. RESULTS AND CONCLUSIONS: Phenylalanine treatment significantly alleviated chilling injury in plum fruits by enhancing antioxidant capacity and increasing the activity of phenylalanine ammonia lyase enzyme (PAL). Phenylalanine-treated fruits had higher mass fractions of ascorbic acid, anthocyanins, flavonoids and phenols, as well as a higher total antioxidant activity than the control fruits during low temperature storage. Phenylalanine at 7.5 mM was the most effective treatment in enhancing the activity of PAL, the accumulation of phenolic compounds and in reducing the severity of chilling injury. Treatments delayed mass loss and maintained fruit firmness. In addition, the application of 7.5 mM phenylalanine improved the activities of antioxidant enzymes (superoxide dismutase, catalase and ascorbate peroxidase), decreased the accumulation of hydrogen peroxide, and increased the endogenous content of proline. Moreover, phenylalanine maintained membrane integrity, manifested by a reduced electrolyte leakage and malondialdehyde accumulation. NOVELTY AND SCIENTIFIC CONTRIBUTION: In the current study, chilling injury had a positive correlation with the activities of PAL and antioxidant enzymes. However, negative correlations were observed between the chilling injury and ascorbic acid mass fraction, and antioxidant capacity. Considering the results, phenylalanine treatment could be an encouraging approach to alleviate the severity of chilling injury and thus preserve nutritional quality of plums during low temperature storage.

Evaluating the Toxic Impacts of Cadmium Selenide Nanoparticles on the Aquatic Plant Lemna minor.

Cadmium selenide nanoparticles (CdSe NPs) were synthesized by an easy and simple method and their properties were assessed by XRD, TEM and SEM techniques. The effects of CdSe NPs as well as Cd2+ ions on Lemna minor plants were investigated. The absorption of CdSe NPs by the plants had some adverse consequences that were assessed by a range of biological analyses. The results revealed that both CdSe NPs and the ionic form of cadmium noticeably caused toxicity in L. minor. Morphological parameters as well as peroxidase (POD) activity were deteriorated. In contrast, the activities of some other antioxidant enzymes (superoxide dismutase (SOD) and catalase (CAT)) as well as the contents of total phenol and flavonoids went up. Taken all together, it could be implied that CdSe NPs as well as Cd2+ were highly toxic to plants and stimulated the plant defense system in order to scavenge produced reactive oxygen species (ROS).

Pre-véraison treatment of salicylic acid to enhance anthocyanin content of grape (Vitis vinifera L.) berries.

BACKGROUND: Grape berries produce significant amounts of phenolic compounds. These are an essential qualitative factor due to their nutritional value and effect on berry color and texture. Salicylic acid (SA) and its derivatives usually lead to enhancement of phenolic content in plant tissues. The present study was conducted to evaluate the effect of different levels of SA (0.0, 50.0, 100.0, and 200.0 mM) on the production of phenolic compounds and the derivatives (anthocyanin and flavonoid) in the grape berries, with emphasis on malvidin-3-O-ß glucoside as a regular anthocyanin in red grapes. RESULT: The results showed that total phenolics content were significantly enhanced in SA-treated (100.0 and 200.0 mM) berries compared to untreated ones. Salicylic acid treatment at all concentrations considerably improved the anthocyanin content in the berries and, compared with untreated berries, the accumulation of malvidin-3-O-ß glucoside was higher in SA-treated fruits. In particular, the 200.0 mM concentration caused approximately two times more malvidin-3-O-ß glucoside than the control. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging capacity of the fruits treated with SA were significantly higher than those of the untreated berries. The activity of phenylalanine ammonia-lyase (PAL) in SA treated fruits significantly increased as compared with the untreated clusters. CONCLUSION: A general evaluation of the current results leads us to the conclusion that SA is a suitable and recommendable treatment for improving and increasing the phenolic and antioxidant capacity of grape berries. Spraying grape berries at pre-véraison stage with SA could therefore be a convenient strategy to increase quality and nutritional value of grape berries considerably. © 2019 Society of Chemical Industry.

Humic acid and grafting as sustainable agronomic practices for increased growth and secondary metabolism in cucumber subjected to salt stress.

Salinity stress poses a significant treat to crop yields and product quality worldwide. Application of a humic acid bio stimulant and grafting onto tolerant rootstocks can both be considered sustainable agronomic practices that can effectively ameliorate the negative effects of salinity stress. This study aimed to assess the above mentioned ameliorative effects of both practices on cucumber plants subjected to saline environments. To attain this goal a factorial experiment was carried out in the form of a completely randomized design with three replications. The three factors considered were (a) three different salinity levels (0, 5, and 10 dS m-1 of NaCl), (b) foliar application of humic acid at three levels (0, 100, and 200 mg L-1), and (c) both grafted and ungrafted plants. Vegetative traits including plant height, fresh and dry weight and number of leaf exhibited a significant decrease under increasing salinity stress. However, the application of humic acid at both levels mitigated these effects compared to control plants. The reduction in relative water content (RWC) of the leaf caused by salinity, was compensated by the application of humic acid and grafting. Thus, the highest RWC (86.65%) was observed in grafting plants with 0 dS m-1 of NaCl and 20 mg L-1 of humic acid. Electrolyte leakage (EL) increased under salinity stress, but the application of humic acid and grafting improved this trait and the lowest amount of EL (26.95%) was in grafting plants with 0 dS m-1 of NaCl and 20 mg L-1 of humic acid. The highest amount of catalase (0.53 mmol H2O2 g-1 fw min-1) and peroxidase (12.290 mmol H2O2 g-1 fw min-1) enzymes were observed in the treatment of 10 dS m-1 of NaCl and 200 mg L-1 humic acid. The highest amount of total phenol (1.99 mg g-1 FW), total flavonoid (0.486 mg g-1 FW), total soluble carbohydrate (30.80 mg g-1 FW), soluble protein (34.56 mg g-1 FW), proline (3.86 µg g-1 FW) was in grafting plants with 0 dS m-1 of NaCl and 200 mg L-1 of humic acid. Phenolic acids and phenylalanine ammonia lyase (PAL) and polyphenol oxidase (PPO) enzymes increased with increasing salinity and humic acid levels. Contrary to humic acid, salt stress increased the sodium (Na+) and chlorine (Cl-) and decreased the amount of potassium (K+) and calcium (Ca2+) in the root and leaf of ungrafted cucumber. However, the application 200 mg L-1 humic acid appeared to mitigate these effects, thereby suggesting a potential role in moderating physiological processes and improving growth of cucumber plants subjected to salinity stress. According to the obtained results, spraying of humic acid (200 mg L-1) and the use of salt resistant rootstocks are recommended to increase tolerance to salt stress in cucumber. These results, for the first time, clearly demonstrated that fig leaf gourd a new highly salt-tolerant rootstock, enhances salt tolerance and improves yield and quality of grafted cucumber plants by reducing sodium transport to the shoot and increasing the amount of compatible osmolytes.

Enhancing Postharvest Quality and Shelf Life of Strawberries through Advanced Coating Technologies: A Comprehensive Investigation of Chitosan and Glycine Betaine Nanoparticle Treatments.

The application of natural polymer-based coatings presents a viable approach to prolong the longevity of fruits and tissue damage. This study investigates the impact of treatments involving glycine betaine (GB), chitosan (CTS), and chitosan-coated glycine betaine nanoparticles (CTS-GB NPs) on preserving the quality and reducing decay in strawberry fruits. The fruits were subjected to treatments with GB (1 mM), CTS (0.1%), CTS-GB NPs (0.1%), or distilled water at 20 °C for 5 min, followed by storage at 4 °C for 12 days. The results indicate that CTS and CTS-GB NPs treatments resulted in the highest tissue firmness, total anthocyanin content, and ascorbate peroxidase activity, while exhibiting the lowest decay percentage and weight loss, as well as reduced malondialdehyde levels at the end of storage. GB, CTS, and CTS-GB NPs treatments demonstrated elevated catalase activity and antioxidant capacity, coupled with lower electrolyte leakage and hydrogen peroxide levels. These treatments did not significantly differ from each other but were markedly different from the control. The results substantiate that CTS and CTS-GB NPs treatments effectively preserve strawberry quality and extend storage life by bolstering antioxidant capacity and mitigating free radical damage.

Next generation chemical priming: with a little help from our nanocarrier friends.

Plants are exposed to multiple threats linked to climate change which can cause critical yield losses. Therefore, designing novel crop management tools is crucial. Chemical priming has recently emerged as an effective technology for improving tolerance to stress factors. Several compounds such as phytohormones, reactive species, and synthetic chimeras have been identified as promising priming agents. Following remarkable developments in nanotechnology, several unique nanocarriers (NCs) have been engineered that can act as smart delivery systems. These provide an eco-friendly, next-generation method for chemical priming, leading to increased efficiency and reduced overall chemical usage. We review novel engineered NCs (NENCs) as vehicles for chemical agents in advanced priming strategies, and address challenges and opportunities to be met towards achieving sustainable agriculture.

Fish Waste-A Novel Bio-Fertilizer for Stevia (Stevia rebaudiana Bertoni) under Salinity-Induced Stress.

Currently, different strategies, including the application of bio-fertilizers, are used to ameliorate the adverse effects posed by salinity stress as the major global problem in plants. Fish waste is suggested as a novel bio-fertilizer to mitigate the effects of biotic and abiotic stresses. In this investigation, an experiment was conducted to investigate the effects by applying different concentrations (0, 5, 10, and 15% (v/v)) of fish waste bio-fertilizer on stevia plants grown under salt stress conditions (0, 20, 40, and 60 mM of NaCl). Results showed that salinity negatively affected growth parameters, the photosynthetic pigments, the relative water content, and the chlorophyll fluorescence parameters while increased the activity of antioxidant enzymes, total phenol, hydrogen peroxide (H2O2), malondialdehyde (MDA), proline, and total carbohydrates compared with control samples. On the other hand, the application of fish waste bio-fertilizer mitigated the effects of salinity stress by enhancing growth and mitigating stress-relative markers, especially at the highest salinity level (60 mM). Overall, fish waste bio-fertilizer could be considered a sustainable, innovative approach for the alleviation of salinity stress effects in plants and, in addition, fish waste bio-fertilizer did not cause more salinity issues, at least with the applied doses and experiment time, which is an imperative aspect.

Foliar spraying with amino acids and their chitosan nanocomposites as promising way to alleviate abiotic stress in iceberg lettuce grown at different temperatures.

We analyzed the effects of foliar spraying with amino acids, chitosan (CHS) and nanocomposites (NCs) of chitosan with the amino acids proline, L-cysteine and glycine betaine (CHS-Pro NCs; CHS-Cys NCs, CHS-GB NCs, respectively) on the changes in the physiological and biochemical parameters of iceberg lettuce grown at the control temperature (20 °C) and under chilling conditions (4 °C). The physicochemical parameters of the phospholipid monolayers (PLs) extracted from plants showed the effects of the treatments on the properties of the monolayers, namely, the packing density and flexibility. We observed increased accumulation of proline at 4 °C, and differences in the concentrations of sugars in most of the analyzed variants were a consequence of the lowered temperature and/or the use of organic compounds. A temperature of 4 °C caused a significant increase in the L-ascorbic acid level compared with that at 20 °C. Differences were also found in glutathione (GSH) content depending on the temperature and treatment with the tested organic compounds. CHS NCs loaded with Pro and GB were effective at increasing the amount of phenols under stress temperature conditions. We noted that a significant increase in the antioxidant activity of plants at 4 °C occurred after priming with Cys, CHS-Cys NCs, Pro and CHS-Pro NCs, and the CHS nanocomposites were more effective in this respect. Both low-temperature stress and foliar spraying of lettuce with various organic compounds caused changes in the activity of antioxidant enzymes. Two forms of dismutase (SOD), iron superoxide dismutase (FeSOD) and copper/zinc superoxide dismutase (Cu/ZnSOD), were identified in extracts from the leaves of iceberg lettuce seedlings. The application of the tested organic compounds, alone or in combination with CHS, increased the amount of malondialdehyde (MDA) in plants grown under controlled temperature conditions. Chilling caused an increase in the content of MDA, but some organic compounds mitigated the impact of low temperature. Compared with that of plants subjected to 20 °C, the fresh weight of plants exposed to chilling decreased. However, the tested compounds caused a decrease in fresh weight at 4 °C compared with the corresponding control samples. An interesting exception was the use of Cys, for which the difference in the fresh weight of plants grown at 20 °C and 4 °C was not statistically significant. After Cys application, the dry weight of the chilled plants was greater than that of the chilled control plants but was also greater than that of the other treated plants in this group. To our knowledge, this is the first report demonstrating that engineered chitosan-amino acid nanocomposites could be applied as innovative protective agents to mitigate the effects of chilling stress in crop plants.

A chromosome-level genome assembly for the amphibious plant Rorippa aquatica reveals its allotetraploid origin and mechanisms of heterophylly upon submergence.

The ability to respond to varying environments is crucial for sessile organisms such as plants. The amphibious plant Rorippa aquatica exhibits a striking type of phenotypic plasticity known as heterophylly, a phenomenon in which leaf form is altered in response to environmental factors. However, the underlying molecular mechanisms of heterophylly are yet to be fully understood. To uncover the genetic basis and analyze the evolutionary processes driving heterophylly in R. aquatica, we assembled the chromosome-level genome of the species. Comparative chromosome painting and chromosomal genomics revealed that allopolyploidization and subsequent post-polyploid descending dysploidy occurred during the speciation of R. aquatica. Based on the obtained genomic data, the transcriptome analyses revealed that ethylene signaling plays a central role in regulating heterophylly under submerged conditions, with blue light signaling acting as an attenuator of ethylene signal. The assembled R. aquatica reference genome provides insights into the molecular mechanisms and evolution of heterophylly.