Authors:P. Bónis, T. Árendás, I. Jócsák, C. Mikecz, G. Micskei, and L. Marton
Inbred maize lines were treated with normal and double rates of post-emergence herbicides in a small-plot field experiment in one dry and one wet year. The chlorophyll a + b content of symptom-free ear-leaves was determined using a spectrophotometer after 50% silking in order to determine whether various rates of post-emergence herbicides had any effect on the chlorophyll content at flowering and how this was influenced by the type of year. The chlorophyll a + b content of the inbred lines was greatly dependent on the year, with values twice as high in the wet year as in the dry year. Treatment with tembotrione + isoxadifen-ethyl had no effect on the chlorophyll content in either year. Both rates of mesotrione + terbutylazine reduced the chlorophyll a + b content of one stress-sensitive inbred line in the dry year, but not in the wet year. In the wet year bentazone + dicamba increased the chlorophyll content, but only for one line was this effect significant irrespective of the dose. In the dry year the double dose caused a significant increase in this genotype, but the chlorophyll contents of the other lines did not differ significantly from the control.
Authors:Zoltán Mayer, Nguyen Hong Duc, Zita Sasvári, and Katalin Posta
The association between terrestrial plants and arbuscular mycorrhizal (AM) fungi is one of the most common and widespread mutualistic plant-fungi interaction. AM fungi are of beneficial effects on the water and nutrient uptake of plants and increase plant defense mechanisms to alleviate different stresses. The aim of this study was to determine the level of polyphenol oxidase (PPO), guaiacol peroxidase (POX) and glutathione S-transferase (GST) enzyme activities and to track the expression of glutathione S-transferase (GST) gene in plant-arbuscular mycorrhizal system under temperature- and mechanical stress conditions. Our results suggest that induced tolerance of mycorrhizal sunflower to high temperature may be attributed to the induction of GST, POX and PPO enzyme activities as well as to the elevated expression of GST. However, the degree of tolerance of the plant is significantly influenced by the age which is probably justified by the energy considerations.
Authors:B. Varga, S. Bencze, T. Janda, and O. Veisz
The impacts of climate modification were examined in terms of changes in the stress tolerance of winter wheat varieties. The enzyme reactions of two winter wheat varieties to drought stress, simulated by water withholding in three different phenophases, were analysed in a phytotron experiment in the Centre for Agricultural Research, Hungarian Academy of Sciences. Plants were raised either at ambient CO2 level or at twice this concentration. The quantities of glutathione reductase (GR), glutathione-S-transferase (GST), catalase (CAT), guaiacol peroxidase (POD) and ascorbate peroxidase (APX) were determined from leaf samples collected at the end of the drought treatment.The results showed that antioxidant enzymes may help to counterbalance the reactive oxygen species induced by stress during various stages of the vegetation period. Although there were substantial differences in the changes induced in the activity of individual enzymes by modifications in environmental factors, this activity and its response to stress depended not only on these factors, but also on the developmental stage of the plant. Modifications in enzyme activity could indicate that enhanced CO2 concentration delayed the development of drought stress up to first node appearance, and stimulated antioxidant enzyme activity when drought occurred during ripening.
Authors:A. B. A. Ahmed, A. S. Rao, M. V. Rao, and R. M. Taha
Gymnemic acid (GA), a well known anti-diabetic compound has been detected in methanol extracts of intact leaves and in vitro callus cultures derived from leaf explants of Gymnema sylvestre. Callus biomass was developed in MS medium with optimum plant growth regulators (OPGRs) of 2,4-D (1.5 mg L−1) + KN (0.5 mg L−1) under abiotic stress conditions at 45 days determined by growth curve analysis. GA detection and quantification were carried out using thin-layer chromatography (TLC), highperformance thin-layer chromatography (HPTLC), high-performance liquid chromatography (HPLC), and gravimetric techniques. GA detection peak area and their absorption spectra were evaluated through HPTLC and HPLC with the standard GA. Quantification of GA had showed the linearity, accuracy, robustness and precision by HPLC. GA content was significantly higher in gravimetric method than HPLC. All these methods were found to be simple, accurate, selective and rapid and could be successfully applied for the determination of GA. It could have potential as a pharmaceutical drug for Type 1 diabetes mellitus (IDDM) and obesity.
Authors:G. Gadimaliyeva, N. Aminov, A. Jahangirov, H. Hamidov, A. Abugalieva, V. Shamanin, and A. Morgounov
Hexaploid synthetic wheat, derived from crosses between durum wheat and Aegilops tauschii, is widely accepted as an important source of useful traits for wheat breeding. During 2015 and 2016, three groups of synthetics were studied in Azerbaijan (3 sites) and Russia (1 site). Group 1 comprised CIMMYT primary synthetics derived from eastern European winter durum wheats crossed to Ae. tauschii accessions from the Caspian Sea basin. Group 2 included lines derived from CIMMYT synthetics × bread wheat crosses. Group 3 consisted of synthetics developed in Japan by crossing durum variety Langdon with a diverse collection of Ae. tauschii accessions. Varieties Bezostaya-1 and Seri were used as checks. Group 1 synthetics were better adapted and more productive than those in group 3, indicating that the durum parent plays an important role in the adaptation of synthetics. Compared to Bezostaya-1 synthetics produced fewer spikes per unit area, an important consideration for selecting bread wheat parents for maintenance of productivity. Synthetics had longer spikes but were not generally free-threshing. All synthetics and derivatives had 1000-kernel weights comparable to Bezostya-1 and significantly higher than Seri. All primary synthetics were resistant to leaf rust, several to stem rust, and few to stripe rust. Superior genotypes from all three groups that combine high expression of spike productivity traits and stress tolerance index were identified.
Drought is one of most important environmental factors inhibiting photosynthesis and decreasing growth and productivity of plants. The sensitivity of crop plants such as wheat to soil drought is particularly serious during reproductive phase is extremely sensitive to plant water status. The aim of this work was to study the effects of drought stress on photosynthesis, photosynthetic pigments, soluble proteins, a-tocopherol and abscisic acid content in six wheat genotypes, two tolerant (Daric and 92 Zhong), two moderately tolerant (Sabalan and DH-2049-3) and two sensitive (Shark and Tevee’s’). Total chlorophyll content, relative water content and chlorophyll a/b ratio decreased after long-time drought stress, that decrease in sensitive genotypes was higher than others. Net photosynthesis and stomatal conductance decreased significantly (P < 0.05) in flag leaves of our genotypes under drought stress after pollination, that decrease in sensitive genotypes was higher, too. Abscisic acid content, soluble protein content and a-tocopherol increased under drought stress, that increase in tolerant genotypes was higher. There was a significant negative correlation (P < 0.05) between photosynthesis factors and abscisic acid content in flag leaves of all genotypes. It can be concluded that Daric and 92 Zhong had a better photosynthesis factors compared to other genotypes and showed a higher capacity to tolerate drought stress.
Shoots of ten day old seedlings of nineteen wheat genotypes were evaluated for proline metabolism, H2O2, thiobarbituric acid reactive substances (TBARS) and 2,2 diphenyl-picrylhydrazyl (DPPH) radical scavenging activity under water deficit, water withholding and salinity stress conditions. Principle component analysis demarcated four groups: i.e. drought tolerant (Excalibar, Krichauff, Babax, Drysdale, Gladius and C306), salt tolerant (Kharchia, Type11, Krl 1-4 and Krl 19), low stress tolerant (C273, C518 and C591) and susceptible (HD2967, PBW621, WH1105, HD3086, PBW660 and PBW175). Salt stress treatment affected the length, fresh weight and dry weight of seedlings of all studied genotypes in comparison to water deficit and water withholding condition which may be due to higher contents of TBARS. Shoots of salt and drought tolerant genotypes possessed higher proline content and DPPH radical scavenging activity alongwith reduced content of TBARS in parallel with decreased H2O2 content under water stress conditions. The activities of proline synthesizing enzymes i.e. pyrroline-5-carboxylate synthetase (P5CS) and pyrroline-5-carboxylate reductase (P5CR) were significantly higher than proline degrading enzyme viz. proline dehydrogenase (PDH) under water stress as compared to salinity stress conditions. Overall, results indicated that P5CS, P5CR and PDH activities led to higher build up of proline under water stress, which might play a significant role in improving membrane stability by increasing radical scavenging activity and finally imparting stress tolerance in specific wheat genotypes.
plants to improve abioticstress tolerance . In: Hasanuzzaman , M. (Ed.), Plant ecophysiology and adaptation under climate change: mechanisms and perspectives II . Springer , Singapore , pp. 477 – 490 . Mozafarian , M. and Kappel , N. ( 2019