Rezisztencia-formák felhasználása a növények immunizálására és ellenálló, transzgenikus növények nemesítésére = Application of resistance forms for immunizing plants against pathogenic infections and for breeding disease resistant transgenic crops

A ROS (pl. O2.-, H2O2) felhalmozódása a biotróf patogének által okozott betegségek ellen idéz elő rezisztenciát, a magas szintű antioxidáns kapacitás pedig tüneti rezisztenciát idéz elő nekrotróf kórokozók ellen. - Sikerült olyan dohány- és burgonyavonalakat előállítanunk, amelyek egy szuperoxid-dizmutáz (SOD) és kataláz (CAT) antioxidáns transzgént tartalmaznak. - Az antioxidáns kapacitás fokozását más úton is elértük. Ha kis koncentrációjú H2O2-vel kezeltük a dohányokat, ezek antioxidáns kapacitása jelentősen fokozódott. Az "immunizáló hatás" miatt tüneti rezisztenciát mutattak vírus-, baktérium- és gombakórokozók ellen. - A nem-gazda rezisztencia lényegének megismerése érdekében 18 gazdanövény/patogén kapcsolatot elemeztünk a O2.- akkumulációja szempontjából. A fogékony gazda/patogén kapcsolatokban nincs felhalmozódás, a gazda-rezisztens növényekben kb. 48 órával a fertőzés után a O2.- felhalmozódik, és a hiperszenzitív reakció (HR) is kialakul. A nem-gazda rezisztencia esetében az akkumuláció korábban lebonyolódik. Ez oka lehet a HR hiányának, amelyhez hozzájárulhat egy SOD gén és a BAX-inhibitor 1 gén átmeneti aktiválása is. Ha hősokkal és antioxidánsokkal a rezisztens növényekben gátoljuk a O2.--képződést, az ellenálló növény részlegesen fogékonnyá válik. - Kiderítettük, hogy egy kémiai rezisztencia-induktor (DCINA) úgy fejti ki hatását, hogy csökkenti az antioxidáns kapacitást, így fokozódik a H2O2 akkumulációja, és ez ellenállóságot okoz az árpalisztharmat ellen. | Accumulation of ROS in infected plants may cause resistance to biotrophic pathogens, while high antioxidant capacity is responsible for symptom resistance during diseases caused by necrotrophs. - We created transgenic tobacco and potato that overexpress tomato superoxide dismutase and maize catalase genes. - We also increased the plant´s antioxidant capacity by applying low concentrations of H2O2 which 'immunizes' tobacco plants (induces symptom resistance to viral, bacterial and fungal infections). - It was possible to explain the hitherto unknown mechanism of non-host resistance by analyzing accumulation of O2.- in 18 host/pathogen combinations. In susceptible combinations there was no accumulation. In resistant hosts O2.- accumulated ca. 48 hours after infection. O2.- killed the pathogen and induced plant cell death (hypersensitive response, HR). During non-host resistance, accumulation of O2.- occurred rather early, killing the pathogen and inhibiting HR. Temporary activation of the genes SOD and BAX-inhibitor 1 may also contribute to the lack of HR. When we applied heath shock and antioxidant treatments to barley, accumulation of O2.- in infected non-host and host-resistant plants was suppressed and the resistant plants became partially susceptible to powdery mildew. - Analyzing the mechanism of action of a resistance inducer (DCINA), we detected lower antioxidant capacity in treated barley and a twofold accumulation of H2O2 which caused resistance to powdery mildew

Treatment of Sweet Pepper with Stress Tolerance-Inducing Compounds Alleviates Salinity Stress Oxidative Damage by Mediating the Physio-Biochemical Activities and Antioxidant Systems

Salinity stress occurs due to the accumulation of high levels of salts in soil, which ultimately leads to the impairment of plant growth and crop loss. Stress tolerance-inducing compounds have a remarkable ability to improve growth and minimize the effects of salinity stress without negatively affecting the environment by controlling the physiological and molecular activities in plants. Two pot experiments were carried out in 2017 and 2018 to study the influence of salicylic acid (1 mM), yeast extract (6 g L−1), and proline (10 mM) on the physiological and biochemical parameters of sweet pepper plants under saline conditions (2000 and 4000 ppm). The results showed that salt stress led to decreasing the chlorophyll content, relative water content, and fruit yields, whereas electrolyte leakage, malondialdehyde (MDA), proline concentration, reactive oxygen species (ROS), and the activities of antioxidant enzymes increased in salt-stressed plants. The application of salicylic acid (1 mM), yeast extract (6 g L−1), and proline (10 mM) markedly improved the physiological characteristics and fruit yields of salt-stressed plants compared with untreated stressed plants. A significant reduction in electrolyte leakage, MDA, and ROS was also recorded for all treatments. In conclusion, our results reveal the important role of proline, SA, and yeast extracts in enhancing sweet pepper growth and tolerance to salinity stress via modulation of the physiological parameters and antioxidants machinery. Interestingly, proline proved to be the best treatment.</jats:p

Optimizing Medium Composition and Environmental Culture Condition Enhances Antioxidant Enzymes, Recovers <i>Gypsophila paniculata</i> L. Hyperhydric Shoots and Improves Rooting <i>In Vitro</i>

Gypsophila paniculata L. is one of the most important commercial cut flowers worldwide. The plant is sterile and propagated mainly by in vitro culture techniques. However, hyperhydricity hinders its micropropagation and increases mortality during ex vitro acclimatization. Hyperhydric shoots of G. paniculata were proliferated from nodal explants on MS medium without growth regulators that contained 30 g L−1 sucrose, and gelled with 6.0 g L−1 agar. Medium components and environmental culture conditions were optimized to revert hyperhydricity in G. paniculata microshoots and develop an efficient micropropagation protocol for commercial production. Multiple shoots with high quality were successfully regenerated on MS medium fortified with potassium and ammonium nitrate at full concentration, 2.0 mg L−1 paclobutrazol, solidified with 9.0 g L−1agar in Magenta boxes of 62.87 gas exchange/day and incubated under light density of 60 µmol m−2s−1. We recorded 4.33 shoots, 40.00 leaves, 6.33 cm, 2.50 g and 95.00% for number of shoots/explant, number of leaves/shoot, shoot length, shoot fresh weight and normal shoots percentage, respectively. Well-rooted plantlets of G. paniculata were developed from the reverted microshoots, with the rooting percentage (95.00%) on MS medium augmented with 1.0 mg L−1 IBA in Magenta boxes of 62.87 gas exchange/day and 60 µmol m−2s−1 light density. In vitro-rooted plantlets exhibited reduced electrolyte leakage, and enhanced antioxidant enzymes activity of peroxidase, catalase, and polyphenol oxidase due to good ventilation at the highest gas exchange rate of the culture vessels

Treatment of Sweet Pepper with Stress Tolerance-Inducing Compounds Alleviates Salinity Stress Oxidative Damage by Mediating the Physio-Biochemical Activities and Antioxidant Systems

Salinity stress occurs due to the accumulation of high levels of salts in soil, which ultimately leads to the impairment of plant growth and crop loss. Stress tolerance-inducing compounds have a remarkable ability to improve growth and minimize the effects of salinity stress without negatively affecting the environment by controlling the physiological and molecular activities in plants. Two pot experiments were carried out in 2017 and 2018 to study the influence of salicylic acid (1 mM), yeast extract (6 g L&minus;1), and proline (10 mM) on the physiological and biochemical parameters of sweet pepper plants under saline conditions (2000 and 4000 ppm). The results showed that salt stress led to decreasing the chlorophyll content, relative water content, and fruit yields, whereas electrolyte leakage, malondialdehyde (MDA), proline concentration, reactive oxygen species (ROS), and the activities of antioxidant enzymes increased in salt-stressed plants. The application of salicylic acid (1 mM), yeast extract (6 g L&minus;1), and proline (10 mM) markedly improved the physiological characteristics and fruit yields of salt-stressed plants compared with untreated stressed plants. A significant reduction in electrolyte leakage, MDA, and ROS was also recorded for all treatments. In conclusion, our results reveal the important role of proline, SA, and yeast extracts in enhancing sweet pepper growth and tolerance to salinity stress via modulation of the physiological parameters and antioxidants machinery. Interestingly, proline proved to be the best treatment

Exogenous Ascorbic Acid Induced Chilling Tolerance in Tomato Plants Through Modulating Metabolism, Osmolytes, Antioxidants, and Transcriptional Regulation of Catalase and Heat Shock Proteins

Chilling, a sort of cold stress, is a typical abiotic ecological stress that impacts the development as well as the growth of crops. The present study was carried to investigate the role of ascorbic acid root priming in enhancing tolerance of tomato seedlings against acute chilling stress. The treatments included untreated control, ascorbic acid-treated plants (AsA; 0.5 mM), acute chilling-stressed plants (4 &deg;C), and chilling stressed seedlings treated by ascorbic acid. Exposure to acute chilling stress reduced growth in terms of length, fresh and dry biomass, pigment synthesis, and photosynthesis. AsA was effective in mitigating the injurious effects of chilling stress to significant levels when supplied at 0.5 mM concentrations. AsA priming reduced the chilling mediated oxidative damage by lowering the electrolyte leakage, lipid peroxidation, and hydrogen peroxide. Moreover, up regulating the activity of enzymatic components of the antioxidant system. Further, 0.5 mM AsA proved beneficial in enhancing ions uptake in normal and chilling stressed seedlings. At the gene expression level, AsA significantly lowered the expression level of CAT and heat shock protein genes. Therefore, we theorize that the implementation of exogenous AsA treatment reduced the negative effects of severe chilling stress on tomato

Physiological and Biochemical Changes in Vegetable and Field Crops under Drought, Salinity and Weeds Stresses: Control Strategies and Management

Weeds are one of the most damaging biotic stresses in crop production, and drought and salinity are considered the most serious abiotic stresses. These factors harmfully affect growth and development in several vegetable and field crops by causing harmful effects on physiological and biochemical characteristics such as water uptake, photosynthesis, relative water content, electrolyte leakage, and antioxidant compounds linked with oxidative stress and the accumulation of reactive oxygen species (ROS). These oxidative stress-related components affect most physiological and biochemical characteristics in plants under natural conditions and environmental stresses, especially weed infestation, salinity, and drought stress. ROS such as superoxide (O2&bull;&minus;), hydrogen peroxide (H2O2), peroxyl radical (ROO&bull;), and singlet oxygen (1O2) are very important molecules produced naturally as by-products of metabolic processes in chloroplasts, mitochondria, peroxisomes, and the apoplast. Under stress conditions such as weed infestation, drought and salinity, the morphological and yield characteristics of stressed plants are negatively affected; however, superoxide (O2&bull;&minus;) and hydrogen peroxide (H2O2) are significantly increased. The negative impact of weeds can be mitigated with integrated controls which include herbicides, allelopathy, and crop rotation as well as the different methods for weed control. The defense system in various crops mainly depends on both enzymatic and nonenzymatic antioxidants. The enzymatic antioxidants include superoxide dismutase, glutathione reductase, and catalase; nonenzymatic antioxidants include ascorbic acid, carotenoids, &alpha;-Tocopherols, proline, glutathione, phenolics, and flavonoids. These antioxidant components can scavenge various ROS under several stresses, particularly weeds, drought and salinity. In this review, our objective is to shed light on integrated weeds management and plant tolerance to salinity and drought stresses associated with the ROS and the induction of antioxidant components to increase plant growth and yield in the vegetable and field crops

Physiological and Biochemical Changes in Vegetable and Field Crops under Drought, Salinity and Weeds Stresses: Control Strategies and Management

Weeds are one of the most damaging biotic stresses in crop production, and drought and salinity are considered the most serious abiotic stresses. These factors harmfully affect growth and development in several vegetable and field crops by causing harmful effects on physiological and biochemical characteristics such as water uptake, photosynthesis, relative water content, electrolyte leakage, and antioxidant compounds linked with oxidative stress and the accumulation of reactive oxygen species (ROS). These oxidative stress-related components affect most physiological and biochemical characteristics in plants under natural conditions and environmental stresses, especially weed infestation, salinity, and drought stress. ROS such as superoxide (O2•−), hydrogen peroxide (H2O2), peroxyl radical (ROO•), and singlet oxygen (1O2) are very important molecules produced naturally as by-products of metabolic processes in chloroplasts, mitochondria, peroxisomes, and the apoplast. Under stress conditions such as weed infestation, drought and salinity, the morphological and yield characteristics of stressed plants are negatively affected; however, superoxide (O2•−) and hydrogen peroxide (H2O2) are significantly increased. The negative impact of weeds can be mitigated with integrated controls which include herbicides, allelopathy, and crop rotation as well as the different methods for weed control. The defense system in various crops mainly depends on both enzymatic and nonenzymatic antioxidants. The enzymatic antioxidants include superoxide dismutase, glutathione reductase, and catalase; nonenzymatic antioxidants include ascorbic acid, carotenoids, α-Tocopherols, proline, glutathione, phenolics, and flavonoids. These antioxidant components can scavenge various ROS under several stresses, particularly weeds, drought and salinity. In this review, our objective is to shed light on integrated weeds management and plant tolerance to salinity and drought stresses associated with the ROS and the induction of antioxidant components to increase plant growth and yield in the vegetable and field crops

Exogenous Application of Proline and Salicylic Acid can Mitigate the Injurious Impacts of Drought Stress on Barley Plants Associated with Physiological and Histological Characters

Barley is a very important crop worldwide and has good impact in preserving food security. The impacts of 10 mM proline and 0.5 mM salicylic acid were evaluated on water stressed barley plants (Hordeum vulgare L. Giza126). Salicylic acid and proline treatments led to increased stem length, plant dry weights, chlorophyll concentration, relative water content, activity of antioxidant enzymes, and grain yield under drought stress. Nevertheless, lipid peroxidation, electrolyte leakage (EL), superoxide (O2&middot;&minus;), and hydrogen peroxide (H2O2) significantly decreased in treated barley plants with proline and salicylic acid in both growing seasons as compared with drought treatment only, which caused significant decrease in stem length, plant dry weights, chlorophyll concentration, activity of antioxidant enzymes, as well as biological and grain yield. These results demonstrated the importance of salicylic acid and proline as tolerance inducers of drought stress in barley plants