Powdery mildew resistance of barley in Southern Dagestan

Background. The most effective way of protecting crops from diseases and pests is the breeding and cultivation of resistant varieties. The hydrothermal regime in the southern plains of Dagestan favors damage to barley plants by the causative agent of powdery mildew. The high level of disease progress observed annually helps to reliably assess the resistance of collection accessions to the pathogen.Materials and methods. The research material included 1361 barley accessions (570 improved cultivars and 791 landraces) of different ecogeographic origin and growth habit. Field experiments were launched concurrently with winter sowing. Powdery mildew resistance was scored during the heading period and in the milk ripeness phase using a point scale. Each accession was assessed for at least three years.Results and conclusions. The results of a long-term study disclosed a significant intraspecific variability of barley collection accessions in their resistance to powdery mildew. A significant part of the studied barley accessions (63.1%) appeared susceptible to the pathogen. The occurrence frequency of disease-resistant accessions was 11.0%, while those with medium resistance reached 25.9%. Among the landraces, four resistant accessions from the Abyssinian, West Asian and Mediterranean centers of crop origin were identified. Seventeen barley varieties resistant to powdery mildew (predominantly originated from Western Europe) are recommended for use in breeding for immunity

Genetic diversity of barley accessions from East Asian countries in terms of resistance to powdery mildew

Background. Barley is an ancient crop currently cultivated in more than 100 countries. High adaptability makes it possible to cultivate it in environments unfavorable for many other crops. At the same time, fungal diseases can have a negative impact on its grain yield and quality. One of the most harmful is the fungus Blumeria graminis (DC.) Golovin ex Speer f. sp. hordei Marchal. The pathogen can overcome a cultivar’s resistance, resulting in significant harvest losses. There is a need for a constant search for new effective sources of resistance to powdery mildew for barley breeding.Materials and methods. A set of 950 barley accessions from the East Asian center of the crop’s morphogenesis were studied at the adult stage of plant development. They were screened and crossed in the fields of Pushkin and Pavlovsk Laboratories of VIR (St. Petersburg, Russia). Genetic control of barley resistance to B. graminis was analyzed in a climate chamber under artificial infection pressure with the northwestern population of the fungus. Scoring scales were used for screening.Results and conclusions. Weak development of B. graminis during the heading phase was observed on plants of 38 barley accessions from the East Asian center. High resistance at all stages of development was manifested by 20 genotypes that can be used in breeding programs. Resistance genes in 18 selected forms differed in their effectiveness at the seedling stage of development and during the heading phase. Accessions k-3433, k-10931, k-10934, k-11608, k-17545, k-20272, k-20279, k-20354 and k-27867 had one dominant resistance gene each. Accessions k-11608, k-12278, and k-17545 are protected by the identical gene, while the resistance of k-3433 is induced by a gene that differs from the genes present in accessions k-10931 and k-20279

Synthesis and Testing of Abscisic Acid with Predominant Replacement of Protium Atoms by Tritium in the Cyclohexene Moiety

© 2018, Pleiades Publishing, Inc. Abstract: A procedure for tritiation of predominantly the cyclohexene moiety of abscisic acid was developed. Tritium was introduced by isotope exchange reaction with 100% tritiated water at 220°C in the presence of diisopropylethylamine. The yield of abscisic acid was 50%, and the specific activity was 30.5 Ci/mmol. The labeled product was tested. It was shown that tritiated abscisic acid synthesized by the proposed method did not differ from the unlabeled precursor and could be used for biological assays

Powdery mildew resistance of barley accessions from Dagestan

Powdery mildew caused by the parasitic fungus Blumeria graminis (DC.) Golovin ex Speer f. sp. hordei Marchal is one of the most common diseases of barley. Growing resistant varieties can significantly minimize harmful effects of the pathogen. The specificity in the interaction between the fungus and its host plant requires a continuous search for new donors of the resistance trait. The powdery mildew resistance of 264 barley accessions from Dagestan and genetic control of the trait in resistant forms were studied under field and laboratory conditions. Forty-seven barley lines carrying previously identified powdery mildew resistance genes were also examined. During three years, the experimental material was evaluated under severe infection pressure at the Dagestan Experiment Station of VIR (North Caucasus, Derbent). Juvenile resistance against the Northwest (St. Petersburg, Pushkin) pathogen population was evaluated in a climatic chamber. The genetic control of B. graminis resistance in the selected accessions was studied with the application of hybridological and molecular analyses. The level of genetic diversity of Dagestan barley for effective resistance to powdery mildew is very low. Only two accessions, VIR-23787 and VIR-28212, are resistant against B. graminis at both seedling and adult plant stages. The high-level resistance of breeding line VIR-28212 originating from barley landrace VIR-17554 (Ep-80 Abyssinien) from Ethiopia is controlled by the recessive gene mlo11. Accession VIR-17554 is heterogeneous for the studied trait, with the powdery mildew resistant genotypes belonging to two varieties, dupliatrum (an awnless phenotype) and nigrinudum (an awned phenotype). In accession VIR-23787, a recessive resistance gene distinct from the mlo11 allele was identified. This accession is supposed to be protected by a new, effective pathogen resistance gene

SEMI–DWARF PRODUCTIVE BARLEY LINES

Background. Resistance to lodging is a factor that significantly affects the yield of barley under the conditions of irrigated agriculture and intensive type of farming. Barley resistance to lodging depends on many features, among which the length of the plant stem is more important.Materials and methods. In the southern planar area of Dagestan, from 1993 till 2008, a research was conducted on the intraspecific diversity of cultivated barley (Hordeum vulgare L.) belonging to different ecogeographic groups, and growth types (2,021 accessions). The F1, F2 and F3 hybrids from crosses of the long-stemmed cultivar ‘Sonet’ with semi-dwarf forms were also studied. The selected recombinant lines were evaluated for their productivity and resistance to frit fly (Oscinella frit L.).Results and conclusions. Wide variability (55–155 cm) of cultivated barley in plant height was observed. Under irrigation in the southern Dagestan, the optimum height of plants, providing high resistance to lodging, was 100–115 cm. A number of semidwarf cultivars were identified; among them, ‘Camincent’ (k-30374, Estonia), ‘Pyramid’ (k-30564, France), ‘Ramos’ (k-30315, Moscow Province) and ‘Jo 1632’ (k-30459, Finland) were the most interesting for their set of traits. The short stem of these cultivars is controlled by recessive alleles of genes. We selected productive lines that significantly exceeded their parental forms in grain weight per area unit and resistance to frit fly: L 15/4 (F6 Sonet × Camincent) and L 16/12 (F6 Sonet × Pyramid). These lines can be used to breed lodging-resistant large-grain barley cultivars for cultivation on irrigated lands

ALLELIC DIVERSITY OF THE <i> Ppd </i> AND <i> VRN </i> GENES INVOLVED IN CONTROL OF THE DURATION OF SHOOTING-EARING STAGE IN DAGESTANIAN BARLEY ACCESSIONS

The period between shooting and earing stages was investigated in a group of 265 barley accessions from Dagestan. The accessions k-15008 and k-15013 were characterized by the highest development rate in South Dagestan. In Northwest Russia the early accession k-15027 was revealed. In 207 barley accessions the dominant and recessive alleles of the Ppd and VRN genes involved in control of the period between shooting and earing stages were identified with the use of allele-specific molecular markers. Twenty two groups with different allelic combinations of the loci were revealed. The most numerous groups possessed the Ppd-H1Ppd-H2vrn-H1 Vrn-H2vrnH3 and ppd-H1Ppd-H2vrn-H1Vrn-H2vrnH3 allelic combinations and included 59 and 91 accessions correspondingly

Synthesis and Testing of Abscisic Acid with Predominant Replacement of Protium Atoms by Tritium in the Cyclohexene Moiety

© 2018, Pleiades Publishing, Inc. Abstract: A procedure for tritiation of predominantly the cyclohexene moiety of abscisic acid was developed. Tritium was introduced by isotope exchange reaction with 100% tritiated water at 220°C in the presence of diisopropylethylamine. The yield of abscisic acid was 50%, and the specific activity was 30.5 Ci/mmol. The labeled product was tested. It was shown that tritiated abscisic acid synthesized by the proposed method did not differ from the unlabeled precursor and could be used for biological assays