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Bread wheat spring cultivar Saratovskaya 29 (S29) is a highly drought tolerant. S29, five single chromosome substitution and two introgression lines of this cultivar for chromosomes of second homoeological group were grown in a climatic chamber under optimal and water deficit conditions of water supply. The donor of the three homologous chromosomes 2A, 2B and 2D was the German spring cultivar Yanetskis Probat; the donors of chromosome 2D were the old spring varieties of Western Siberia, Caesium 111 and Sibirka 1818. The donors of 2A chromosome were the species Triticum timopheevii and Aegilops markgrafii. Eleven physiological indexes including water use efficiency, the chlorophyll a, chlorophyll b and carotenoids contents, osmotic substances contents, antioxidant enzymes activities and lipoxygenase activity were measured in leaves of wheat at the stage of beginning of earing. To assess genotypes, we established a comprehensive evaluation value (D) based on various measured physiological parameters and shoot biomass. The D positively correlated with the tolerance of shoot biomass (r = 0.955, P

Density and length of leaf pubescence are important factors of diversity in the response to water deficiency among wheat genotypes. Many studies evidence an important protective value of leaf hairiness in plants, especially under the conditions of drought, thermal loads and increased solar radiation. However, the physiological and adaptive roles of such traits in cereals, including cultivated plants, have not been sufficiently studied to date. The aim of this work was to study the association of morphological characteristics of leaves with parameters of gas exchange and chlorophyll fluorescence in wheat lines carrying a genetically different leaf hairiness. Isogenic and inter-varietal substitution wheat lines were used, carrying various combinations of dominant and recessive alleles of the known genes. A quantitative assessment of the pubescence was carried out in contrasting watering conditions to establish the physiological role of this trait in adaptation to drought. With the help of a portable system for studying the gas exchange and chlorophyll fluorescence, ten parameters of photosynthesis were studied, as well as morphological features of leaves and shoot biomass. It was found that gas exchange parameters are inversely proportional to the density and length of trichomes. In drought conditions, the trichome density increased and the length of trichomes decreased under the observed decrease in the level of gas exchange. A similar dependence was observed for the level of non-photochemical quenching of chlorophyll fluorescence. Under optimal conditions, the poorly haired cultivars exhibited a higher biomass than the densely haired. However, under water deficiency they significantly reduced the biomass and showed a low value of the tolerance index.

The green filamentous alga Ulothrix zonata inhabits Lake Baikal and overgrows the underside of hummocky ice during winter and spring. To clarify physiological adaptations of U. zonata to low temperature and the potential contribution of membrane water permeabilities, the expression level of aquaporins from a winter population growing under the lake ice and in interstitial water was compared with that of benthic summer and autumn populations of algae by immuno-detection using an anti-maize PIP1 (plasma membrane intrinsic protein) antiserum. Algal, and in particular Ulvophycean, transcriptome sequences are only partially available and this higher plant-specific PIP1 epitope has not been detected so far in available genomic datasets. PIP1 expression levels were highest in the ice population and the rise in water temperature during summer was correlated with a drop in PIP1 amounts, which slightly increased again in autumn. ITS2 rDNA (internally transcribed spacer region 2) sequences revealed conspecificity of...

Understanding of the genetic basis of physiological properties, which are most relevant to water-deficit tolerance would be helpful for genomic-assisted improvement of bread wheat. A set of bread wheat inter-varietal single chromosome substitution lines (ISCSLs) of variety ‘Janetzkis Probat’ (JP) in the genetic background of ‘Saratovskaya’ 29 (S29) were used to reveal the critical chromosomes in wheat genome controlling tolerance to water deficit. The same lines were involved in the identification of chromosomes associated with the activity of antioxidant enzymes that are closely related to the detoxification of H2O2 [catalase (CAT), ascorbate peroxidase, dehydroascorbate reductase and glutathione reductase (GR)]. The recipient cultivar S29 was highly drought tolerant while the donor JP was sensitive. Using non-metric multidimensional scaling of yield components and indices of drought tolerance/susceptibility chromosomes 2A and 4D, substitution in the genetic background of S29 was found to lead to a critical decrease of water-deficit tolerance. The drop of tolerance correlated with a sharp decline of cumulative activity of the catalase and the enzymes of ascorbate–glutathione cycle in wheat leaves. Clear evidence was obtained for the involvement of genes present on the homoeologous group 2 chromosomes in the control of GR and CAT activity. Substitution of the chromosome 4D had a significant reducing impact on the CAT activity level.

The various enzyme systems and low molecular weight (LMW) redox agents are related to the folding and polymerization of prolamins in the ripening wheat grains and the formation of baking quality. Protein disulfide isomerases (PDIs) and cyclophylins accelerate "correct" folding of prolamins, which is most likely necessary for the subsequent formation of the macromolecular structure of the gluten protein matrix. PDIs are also involved in the polymerization of prolamins, catalyzing the oxidation of protein sulfhydryl groups. Molecular chaperone binding BiP protein facilitates folding of prolamins, with its role increasing in the stressful conditions. Reducing systems of thioredoxin and glutaredoxin, LMW redox pairs GSH/GSSG and Asc/DHAsc, thiol oxidases, and lipoxygenases (LOXs) regulate redox balance and the rate of polymerization of prolamins at the different stages of grain ripening. Additionally, LOX is probably involved in the protein-starch-lipid interactions between the starch granule and the protein matrix, mediated by puroindolines, determining the formation of grain texture. It is assumed that the high variability of baking quality in different environmental conditions is due to the interaction of labile enzyme systems with the storage proteins in the developing wheat caryopsis.

Variation in tolerance of prolonged drought was identified among a set of single chromosome bread wheat substitution lines, involving the replacement of each cv. Chinese Spring chromosome in turn with its homologue from a synthetic hexaploid (Triticum dicoccoides × Aegilops tauschii). Water stress was applied under controlled conditions by limiting the supply of water to 30% from 100% aqueous soil. The reaction to the resulting long-term drought stress was quantified by three indices, based on grain yield components. Enhanced drought tolerance was associated with the presence of donor chromosomes 1A, 5A, 1D, 3D, 5D and 6D, and enhanced susceptibility with chromosomes 3A, 4B and 7D.

A number of morphological, physiological and phenological traits have been suggested as significant markers of adaptation to drought in bread wheat (Triticum aestivum L.). This study was aimed at the identification of a relationship between dehydroascorbate reductase (DHAR, EC 1.8.5.1) and catalase (CAT, EC 1.11.1.6) activities in leaves of wheat plants and stability of yield components under water deficit. The single chromosome substitution lines of cv. Chinese Spring carrying separate chromosomes from the donor Synthetic 6x, an artificial hexaploid combining the genomes of the two wild species, Triticum dicoccoides (AABB) and Aegilops tauschii (DD), were the objects of the investigations. The activities of the DHAR and CAT were correlated with flag leaf relative water content and two indexes of stability of grain yield components under drought across the set substitution lines. The lines carrying a synthetic hexaploid homologous pair of chromosomes 1B, 1D, 2D, 3D or 4D all expressed a low constitutive level of DHAR and the lines carrying chromosomes 3B, 1D, 2D and 3D a low constitutive level of CAT. All were able to increase this level (by fourfold for DHAR and by 1.5-fold for CAT) in response to stress caused by water deficit. When challenged by drought stress, these lines tended to be the most effective in retaining the water status of the leaves and preventing the grain yield components from being compromised. The discovered genetic variability for enzymes activity in leaves of wheat might be a useful selection criterion for drought tolerance.

For six wheat varieties with different quality it was shown that GSH-dependent protein-disulphide oxidoreductase (TPDO) increases the activity to the third week after anthesis, a period of maximum synthesis of storage proteins in wheat kernels. The study revealed a correlation between TPDO activity in maturing kernels and dough stiffness. The addition of exogenous TPDO to flour significantly increased dough extensibility (from 17 to 49% for cultivars with different quality), which implies the ability of the enzyme to disrupt SS bonds in high-molecular weight gluten polymers.

A quantitative trait locus (QTL) approach was taken to reveal the genetic basis in wheat of traits associated with photosynthesis during a period of exposure to water deficit stress. The performance, with respect to shoot biomass, gas exchange and chlorophyll fluorescence, leaf pigment content and the activity of various ascorbate-glutathione cycle enzymes and catalase, of a set of 80 wheat lines, each containing a single chromosomal segment introgressed from the bread wheat D genome progenitor Aegilops tauschii, was monitored in plants exposed to various water regimes. Four of the seven D genome chromosomes (1D, 2D, 5D, and 7D) carried clusters of both major (LOD >3.0) and minor (LOD between 2.0 and 3.0) QTL. A major QTL underlying the activity of glutathione reductase was located on chromosome 2D, and another, controlling the activity of ascorbate peroxidase, on chromosome 7D. A region of chromosome 2D defined by the microsatellite locus Xgwm539 and a second on chromosome 7D flanked by the marker loci Xgwm1242 and Xgwm44 harbored a number of QTL associated with the water deficit stress response.