Mitigation of salinity impact in spearmint plants through the application of engineered chitosan-melatonin nanoparticles.

High soil salinity represents a critical environmental constraint to crop production. In order to ameliorate the effects of salinity, a plethora of molecules have been applied and promising outcomes have been noted. The beneficial effects of chitosan (CTS) and melatonin (Mel) application, separately, have been previously recorded with respect to plant growth and productivity, leading to the hypothesis that their conjugation in the form of chitosan-melatonin nanoparticles (CTS-HPMC-Mel NPs) could lead to further enhanced performance of plants under control and stress conditions. In this regard, novel CTS-HPMC-Mel NPs were synthesized, characterized and then employed as a chemical priming agent in spearmint (Mentha spicata L.) plants 24 h prior to salinity stress imposition. As expected, salt stress negatively affected morphophysiological attributes such as plant height, leaf number, leaf fresh weight, leaf dry weight, photosynthetic pigments, Fv/Fo, and Fv/Fm. On the other hand, stress-related attributes, such as content of proline, MDA and H2O2, as well as activity of APX and GP enzymes were increased in response to salt stress. However, adverse effects of salt stress were ameliorated with Mel and CTS-HPMC-Mel NP treatments by enhancing morphological traits, proline, antioxidant enzymatic activities, as well as content of dominant constituents of essential oil profile. It is worth noting that conjugated form of Mel with chitosan, in comparison with solo treatment of Mel, was more effective in combating stress effects. To our knowledge, this is the first report to demonstrate that engineered CTS-HPMC-Mel NPs could be applied as an innovative protective agent to mitigate the effects of salinity in crop plants.

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.

Insight into the role of magnetic nutrient solution on leaf morphology and biochemical attributes of Rasha grapevine (Vitis vinifera L.).

The growth, development, and morphology of plants are extremely affected by many internal and external factors. In this regard, plant nourishing solutions take the most impact. Nowadays, the magnetization of nutrient solutions has been recommended as a promising eco-friendly approach for improving the growth and development of plants. This study was designed to explore the potential of magnetic nutrient solutions in altering morphometric characteristics as well as some physiological and nutritional attributes of Rasha grapevines. Magnetic treatments included magnetized nutrient solution (MagS) and pre-magnetized water completed with nutrients (MagW + S) at magnetic field intensities (0.1 and 0.2 T). According to the results, the most considerable changes in leaf shape and size as well as fresh and dry weights were observed in the plants treated with MagS at 0.2 T. Also, MagS 0.2 had a significant effect on increasing photosynthetic pigments, content of total soluble carbohydrates and protein, and activity of antioxidant enzymes. The content of TNK, K, P, Fe, and Cu was considerably amplified by MagW + S 0.2. Overall, the magnetic solutions had favorable influences on physiological, nutritional state, and leaf morphology of grapevines possibly through alerting water and solution properties, mineral solubility, and phytohormones signalling.

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.

Improving the Berry Quality and Antioxidant Potential of Flame Seedless Grapes by Foliar Application of Chitosan-Phenylalanine Nanocomposites (CS-Phe NCs).

The production and sustainability of grape berries with high quality and health-promoting properties is a major goal. In this regard, nano-engineered materials are being used for improving the quality and marketability of berries. In this study, we investigated the potential role of chitosan-phenylalanine nanocomposites (CS-Phe NCs) in improving the quality of Flame Seedless (Vitis vinifera L.) grape berries, such as titratable acidity (TA), pH, total soluble solids (TSS), ascorbic acid, total phenolics, total flavonoids, anthocyanin, 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) radical scavenging activity, and phenylalanine ammonia-lyase (PAL) activity. In this context, grape berries collected in two growing seasons (2018-2019) were screened. Regarding the experimental design, the treatments included chitosan at a 0.5% concentration (CS 0.5%), phenylalanine at 5 mM and 10 mM concentrations (Phe 5 mM and Phe 10 mM), and chitosan-phenylalanine nanocomposites (CS-Phe NCs) at 5 mM and 10 mM concentrations. The lowest TA was recorded in grape berries treated with CS-Phe NCs with a 10 mM concentration. However, treatments enhanced with TSS, which reached the highest value with 10 mM of CS-Phe NCs, were reflected as the highest ratio of TSS/TA with 10 mM of CS-Phe NC treatment. Nanocomposites (NCs) also increased pH values in both study years compared to the control. Similarly, the ascorbic acid and total phenolic content increased in response to NP treatment, reaching the highest value with 5 mM and 10 mM of CS-Phe NCs in 2018 and 2019, respectively. The highest flavonoid content was observed with 5 mM of CS-Phe NCs in both study years. In addition, the anthocyanin content increased with 5 and 10 mM of CS-Phe NCs. PAL activity was found to be the highest with 5 mM of CS-Phe NCs in both study years. In addition, in accordance with the increase in PAL activity, increased total phenolics and anthocyanin, and higher DPPH radical scavenging activity of the grapes were recorded with the treatments compared to the control. As deduced from the findings, the coating substantially influenced the metabolic pathway, and the subsequent alterations induced by the treatments were notably appreciated due to there being no adverse impacts perceived.

Eliciting effects of magnetized solution on physiological and biochemical characteristics and elemental uptake in hydroponically grown grape (Vitis vinifera L. cv. Thompson Seedless).

Hydroponic systems are used as an instrument to solve a wide range of environmental concerns such as climate change, drought, and soil fertility. Effective growing media are vital to the hydroponically plant cultivation system. Plant reaction to the growing media treated by magnetic fields, as an innovative technology, should be investigated since the magnetic field can constitute a non-toxic and non-residual stimulus. In the current study, some physiological and biochemical responses (leaf fresh and dry weight, biomass, leaf area, plant height, stem diameter, photosynthesis pigments, carbohydrates, protein, and proline contents and peroxidase activity (POD)) and elemental uptake of hydroponically grown grapevines to the magnetic solutions (with 0.1 and 0.2 T intensities) were evaluated. The solutions were magnetized in two ways: 1) solutions magnetized after preparing (S 0.1 and S 0.2), and 2) salts were added to the pre-magnetized waters (W + S 0.1 and W + S 0.2). The results revealed that magnetic treatments had effect on increasing of leaf elements uptake including N+, P+, K+, Ca2+, Fe2+, and Zn2+. Magnetic treatments also stimulated chlorophyll content, leaf extension, leaf fresh and dry weight, and biomass accumulation. Carbohydrates content and POD were promoted in grapes treated by S 0.1 and W + S 0.1 than control. W + S 0.1 and S 0.2 increased the proline and protein content, respectively. The findings proposed that solution magnetization application could act as an elicitor agent to mimic the stress condition, but at the lesser level resulting in activation of grape physiological and biochemical processes and elemental state through stress-related responses.

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.

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.

Biochemical composition and antioxidant activity affected by spraying potassium sulfate in black grape (Vitis vinifera L. cv. Rasha).

BACKGROUND: The physiological and metabolic processes involved with grapevine growth and production are influenced by key macro- and micronutrients. Potassium is an essential plant nutrient that affects growth and fruit quality. In this study, the impact of foliar spraying of potassium sulfate (K2 SO4 ) on qualitative characteristics of grape berries was evaluated in the cultivar 'Rasha', a commonly cultivated cultivar in Kurdistan province of Iran. Leaves of the fully grown vines were sprayed with each of the 1.5 and 3 g L-1 K2 SO4 solutions once (1 month after petal senescence) and twice (15 days after first spraying). The control plants were sprayed with distilled water. Various biochemical contents and enzyme activities on the ripe berries were analyzed. RESULTS: Significant increases in anthocyanin, total protein content, and antioxidant enzyme activities were observed in the berries treated twice with 3 g L-1 K2 SO4 . Concentrations of total carbohydrate, phenol, and antioxidant activity in berries sprayed with K2 SO4 were higher than in the controls. We observed a strong correlation between antioxidant activity and different phenolic compounds. CONCLUSION: These findings suggest that K2 SO4 treatment influences biosynthesis of phenolic compounds and antioxidant enzymes. Thus, treatment by K2 SO4 could improve nutritional and qualitative attributes of grape. © 2018 Society of Chemical Industry.