Iron nanoparticle regulate succinate dehydrogenase activity in canola plants under drought stress.

Application of nutrients as nanoparticle (NP) is an operative manner of nutrient supply for plants, especially under stress conditions. The present study was designed to highlight the role of iron NP on drought tolerance and elucidate the underlying mechanisms in drought-stressed canola plants. Drought stress was imposed by polyethylene glycol different concentrations (0, 10 and 15% (W/V)) with or without iron NP (1.5 and 3 mg/l). A comparative study of several physiological and biochemical parameters have been carried out in canola plants treated by drought and iron NP. Stressed-canola plants showed a reduction in growth parameters, whereas iron NP mostly stimulated growth of stressed plants, which was accompanied by reinforcement in defense mechanisms. Regarding impacts on compatible osmolytes, the data revealed that iron NP was able to regulate osmotic potential by increasing protein, proline and soluble sugar contents. The iron NP application was activated the enzymatic defense system (catalase and polyphenol oxidase) and promoted the non-enzymatic antioxidants (phenol, flavonol and flavonoid). Both of these adaptive responses declined free radicals as well as lipid peroxidation and enhanced the membrane stability and drought tolerance of the plants. Enhanced chlorophyll accumulation via induction of protoporphyrin, magnesium protoporphyrin and protochlorophyllide, by iron NP also contributed towards better stress tolerance. Enzymes of Krebs cycle, namely succinate dehydrogenase and aconitase, were induced by iron NP in canola plants grown under drought stress. These results propose a multifaceted involvement of iron NP, through regulation of activity of respiratory enzymes and antioxidant enzymes, production of reactive oxygen species, osmoregulation and secondary metabolites metabolism, in response to drought stress.

Cerium and samarium blocked antioxidant enzymes in wheat plants.

This work was conducted to study positive and negative impacts of cerium (Ce) and samarium (Sm) on two cultivars (Arta and Baharan) in wheat plant. Symbols of stress such as proline, malondialdehyde (MDA) and antioxidant enzymes, which may be complicated in the suppression responses of plants, were also studied. Wheat plants were exposed to 0, 2500, 5000, 7500, 10,000 and 15,000 µM of Ce and Sm for 7 days. The growth enhanced in plants treated with lesser Ce and Sm concentration (2500 µM) and declined in plants treated with upper concentrations as compared to untreated plants. The treatment with 2500 µM of Ce and Sm increased dry weigh in Arta by 68.42 and 20% and in Baharan by 32.14% and 27.3%. Thus, Ce and Sm had hormesis effect on growth in wheat plants. According to plant's growth parameter patterns, Arta cultivar had more sensitive to Sm than to Ce, whereas Baharan cultivar had sensitive to Ce than to Sm. Our results indicated impact of Ce and Sm on proline accumulation depended on the dosage of Ce and Sm. It was observed that Ce and Sm accumulated in wheat plants at higher exposure doses. Increment of MDA content by Ce and Sm treatments showed that these metals caused oxidative stress in wheat plants. Ce and Sm blocked enzymatic antioxidant system (superoxide dismutases, peroxidase and polyphenol peroxidase) in wheat. In wheat plants treated with lower Ce and Sm concentrations higher amounts of non-enzymatic antioxidant metabolites were detected. Thus, we showed the potential negative impact of unsuitable utilization of REEs in plants and suggested growth and interruption in physiological and biochemical mechanisms as a possible factor to recognize the underlying toxicological processes.

Impact of the Static Magnetic Field on Growth, Pigments, Osmolytes, Nitric Oxide, Hydrogen Sulfide, Phenylalanine Ammonia-Lyase Activity, Antioxidant Defense System, and Yield in Lettuce.

Magnetic fields are an unavoidable physical factor affecting living organisms. Lettuce seeds (Lactuca sativa var. cabitat L.) were subjected to various intensities of the static magnetic field (SMF) viz., MF0 (control), SMF1 (0.44 Tesla (T), SMF2 (0.77 T), and SMF3 (1 T) for three exposure times (1, 2, and 3 h). SMF-treated seedlings showed induction in growth parameters and metabolism comparing to control. All photosynthetic pigments were induced markedly under SMF, especially chlorophyll a. SMF at different intensities boosted osmolytes, non-enzymatic antioxidants, and the phenylalanine ammonia-lyase activity over non-magnetized seedlings. Oxidative damage criteria viz., hydrogen peroxide, superoxide radical, and lipid peroxidation, as well as polyphenol oxidase activity, were kept at low values under SMF-treated seeds relative to control, especially SMF2. Electron donors to antioxidant enzymes including nitrate reductase, nitric oxide, and hydrogen sulfide induced via SMF exposure and consequently the activities of superoxide dismutase, glutathione-S-transferases, catalase, and peroxidases family enzymes were also stimulated under SMF, whatever the intensity or the exposure period applied. All these regulations reflected on the enhancement of lettuce yield production which reached 50% over the control at SMF3. Our findings offered that SMF-seed priming is an innovative and low-cost strategy that can improve the growth, bioactive constituents, and yield of lettuce.

Penconazole and calcium ameliorate drought stress in canola by upregulating the antioxidative enzymes.

The aim of this research was to gauge the alternations in the lipid peroxidation and antioxidative enzyme activity in two cultivars (cv. RGS003 and cv. Sarigol) of canola under drought stress and drought tolerance amelioration by penconazole (PEN) and calcium (Ca). Plants were treated with different polyethylene glycol (PEG) concentrations (0, 5, 10 and 15%) without or with PEN (15 mg L-1) and Ca (15 mM). The Ca treatment prevented the negative effects of drought on fresh weight (FW) in RGS003 and Sarigol at 5 and 15% PEG respectively. Ca and PEN/Ca treatments caused significant induction in the proline content in Sarigol at 15% PEG; the latter treatment was accompanied by higher glycine betaine (GB), lower malondialdehyde (MDA) and growth recovery. Hydrogen peroxide (HO2) content in Sarigol was proportional to the severity of drought stress and all PEN, Ca and PEN/Ca treatments significantly reduced the H2O2 content. PEN and PEN/Ca caused alleviation of the drought-induced oxidative stress in RGS003. RGS003 cultivar exhibited significantly higher antioxidative enzymes activity at most levels of drought, which could lead to its drought tolerance and lower MDA content. In contrast to that of Sarigol, the activity of catalase and superoxide dismutase (SOD) increased with Ca and PEN/Ca treatments in RGS003 under low stress. The application of PEN and Ca induced significantly P5CS and SOD expression in RGS003 under drought stress after 24 h. Overall, these data demonstrated that PEN and Ca have the ability to enhance the tolerance against the drought stress in canola plants.

Antioxidative enzymes activities and accumulation of steroids in hairy roots of Trigonella.

Steroidal sapogenins and phytosterols are a group of secondary metabolites which are very considerable in the pharmaceutical industry. Fenugreek (Trigonella foenum-graecum L.) is the good source of these compounds. In recent decades, there is a great interest to production of these compounds by cultivation of transformed roots. In present study, hairy roots induction in two Trigonella species (T. foenum-graeceum, T. monantha) with three strains of Agrobacterium rhizogenes (15,834, A4 and wt) was investigated. Transgenic status of roots was confirmed by PCR using rolB specific primers. Virulence of these strains was examined on explants of leaf, leaf cotyledone and hypocotyle in both species. The best strain was wt for hairy root induction in hypocotyle and leaf explants of T. foenum-graeceum and T. monantha. Significant quantitative differences were showed between shoot, root and hairy roots in both species. Protein content in root and hairy root of both species was significantly lower in comparison with shoot. Superoxide dismutase (SOD) and peroxidase (POX) activities in hairy roots of both species were higher as compared to other organs. The hairy roots of both species showed an ability to synthesize steroidal sapogenins. These results presented that hairy roots could be a suitable procedure for producing sapogenins compounds that have medicinal value in Trigonella.

Different effects of calcium and penconazole on primary and secondary metabolites of Brassica napus under drought.

The effects of penconazole (PEN) and calcium (Ca2+) on physiological and biochemical parameters were investigated in two canola cultivars (RGS003 and Sarigol) under water stress. Drought increased protein content in RGS003, but PEN, Ca2+ and PEN-Ca2+ treatment induced protein content in Sarigol. PEN, Ca2+ and PEN-Ca2+ treatment enhanced soluble sugar content in RGS003. In contrast to Sarigol, drought and PEN treatment induced total phenol content in RGS003. Flavonoid content increased by drought, but Ca2+ and PEN-Ca2+ treatment decreased it in both cultivars. Ca2+ and PEN-Ca2+ treatment enhanced tocopherol content in both cultivars under drought stress. Drought stress increased Phenylalanine ammonia-lyase (PAL) activity in Sarigol. PEN-Ca2+ treatment increased relative expression of PAL and its activity in RGS003. Fatty acid composition was modified by drought, PEN and Ca2+. Saturated fatty acid (stearic acid) content declined but unsaturated fatty acid (oleic acid) content enhanced in both cultivars under drought. The application of PEN and Ca2+ decreased unsaturated fatty acids (linoleic and linolenic acid) in RGS003 under drought. According to our results, PEN and Ca2+ changed physiological and biochemical parameters and therefore these compounds are suggested for reduction of the negative effects of drought stress in canola.

Oxidative damage and antioxidative system in algae.

Reactive oxygen species (ROS) typically produce in algae and act as secondary messengers in numerous cellular processes. Under abiotic stresses, the balance between production and suppression of ROS disappears and causes increase of ROS. Increasing excessive ROS can cause damage to various cellular components comprising cell membranes, proteins and lipids. Algae have an antioxidant defense system to overcome on oxidative damage. Antioxidant defense mechanisms are of two types, namely enzymatic and non-enzymatic antioxidants. The enzymatic antioxidants include superoxide dismutase, catalase, ascorbate peroxidase and glutathione reductase. The non-enzymatic antioxidants include carotenoids, tocopherol, ascorbic acid, glutathione, flavonoids and phenolic compounds. In this review, we describe the various types of ROS and their production, and antioxidant defense mechanisms for ROS suppression.

Improving tolerance against drought in canola by penconazole and calcium.

Drought stress is one of the most important environmental factors that limit plant growth. Canola is an important agricultural crop grown primarily for its edible oil. In this study, penconazole (PEN), a triazole growth regulator, and calcium (Ca2+), a secondary messenger, were used to analyses their role in decease sensitivity and induce tolerance to drought stress in canola. Plants were treated by various PEG concentrations (0, 5, 10, and 15%) without or with PEN (15 mg l-1) and Ca2+ (15 mM). According to the obtained results in two cultivars of canola (RGS003 and Sarigol), improvement of growth by PEN and Ca2+observed at low concentration of drought (5%). Betterment of growth by PEN can be explained by induction in DPPH (1, 1-diphenyl-2- picrylhydrazyl), chlorophyll and P content and reduction in Electrolyte leakage in cultivar RGS003. Growth recovery by PEN is concomitant by increase in DPPH, succinate dehydrogenase, chlorophyll, carotenoid and K+ content in cultivar Sarigol. Ca2+ treatment by induction in Relative water content, DPPH, chlorophyll, carotenoid, indole-3-acetic acid content and the content of Ca2+ and K+ causes increase in growth in cultivar Sarigol. Overall, application of PEN and Ca2+ improved the performance in canola under drought stress. These results provide novel insights about the physiological and molecular roles of PEN and Ca2+ in canola plant tolerance against drought stress.