Complexing of Sulfur(IV) Oxide with Hexamethylenetetramine and Hexamethylenediamine in Aqueous Solutions

Interaction in the sulfur(IV) oxide–hexamethylenetetramine (hexamethylenediamine)–water systems was studied by pH-, redox-, and conductometric titration techniques. The structure and stability of the resulting molecular and ionic complexes were examined in relation to the nature and concentration of the components in solution, as well as to temperature

Cyclotron resonance of extremely conductive 2D holes in high Ge content strained heterostructures

Cyclotron resonance has been observed in steady and pulsed magnetic fields from high conductivity holes in Ge quantum wells. The resonance positions, splittings and linewidths are compared to calculations of the hole Landau levels

Temperature-dependent magnetospectroscopy of HgTe quantum wells

We report on magnetospectroscopy of HgTe quantum wells in magnetic fields up to 45 T in temperature range from 4.2 K up to 185 K. We observe intra- and inter-band transitions from zero-mode Landau levels, which split from the bottom conduction and upper valence subbands, and merge under the applied magnetic field. To describe experimental results, realistic temperature-dependent calculations of Landau levels have been performed. We show that although our samples are topological insulators at low temperatures only, the signature of such phase persists in optical transitions at high temperatures and high magnetic fields. Our results demonstrate that temperature-dependent magnetospectroscopy is a powerful tool to discriminate trivial and topological insulator phases in HgTe quantum wells

New genetic tools for plant defense against parasitic nematodes

Nematodes belong to economically important pests. Here we reviewed the recent data on molecular mechanisms of plant resistance to cyst and gall nematodes including the most devastating Globodera rostochiensis, G. pallida, Heterodera schachtii, Meloidogyne chitwoodi, and M. incognita. The Golden Potato Cyst Nematode (G. rostochiensis, GPCN) may be taken as an example of an economically important pest: in Russia, it occurs in 61 regions with a total area of 1.8 million ha and may cause the yield loss from 19 to 90 %. The biological characteristics of sedentary nematodes makes their agrotechnical control problematic, i.e. the GPCN cysts remain dormant in soil for many years until a susceptible host appears, whereas nematicides are either toxic or inefficient. Introgression of resistance genes (R-genes) from related cultivated or wild species is likely to be the most appropriate way for their biocontrol. The life cycle of sedentary nematodes is based on juveniles’ penetration into the host root where they reprogram plant cells into a syncytium or the so-called ‘giant cells’ and inhibit the plant defense response. Molecular mechanisms of plant-nematode interaction are unusual and this phenomenon provides a very interesting model for the investigation of plant morphogenesis control as well as for the development of new genetic instruments of biocontrol. Here we reviewed recent publications on plant parasitic nematode effectors used for hijacking of the plant immune system, data on R-genes and molecular mechanisms of their activities. In addition, host-induced gene silencing (HIGS) is discussed as a perspective mechanism for nematode biocontrol. HIGS is based on the RNA interference in the cells of the host plant addressed against the nematode genes important for their development and productivity. Several recent investigations demonstrated efficiency of HIGS against sedentary nematodes

Manganese catalysts to obtain olefins from C1-C4 alkanes

Oxidative transformations of C1-C4 alkanes into olefins on oxide manganese catalysts were under study. We also studied oxidative coupling of methane (OCM) into ethylene on deposited and applied on the silicon dioxide catalysts. We studied the influence of chemical composition of catalyst and promotors on the OCM. Adding a little amount of ethane and propane hydrocarbons to methane allows increasing the concentration of ethylene in gases and significantly increasing productivity in ethylene. The study also shows the impact of the amount of manganese and promotors applied on SiO2 on the yield of olefins during the conversion of C3-C4 alkanes

Long-term preservation of modern Russian potato cultivars in the VIR cryobank

Cryopreservation of shoot-tips (apexes) excised from in vitro plants is used for long-term preservation of potato cultivars. The most widely used method for creating potato cryo-collections is droplet-vitrification of shoot-tips which, together with its numerous modifications, is widely used in genebanks. A modified protocol of droplet vitrification method is used at VIR for cryopreservation of shoot tips from in vitro potato plants. This paper presents the results of cryopreservation of modern cultivars which were released by seven Russian breeding centers. In vitro clones used in the cryopreservation experiments were genetically identical to the cultivars’ nomenclatural standards and herbarium vouchers.The frequency of post-thaw regeneration in control experiments after short-term cryopreservation varied from 23.3 to 53.3%, depending on the genotype. Five out of 16 accessions (‘Varâg’, ‘Gusar’, ‘Evpatij’, ‘Solnečnyj’, ‘Tango’)* had low post-cryogenic regenerative capacity from 20 to 30%; the regeneration rate exceeded 30% in 11 accessions, and 8 cultivars (‘Grand’, ‘Zlatka’, ‘Lina’, ‘Safo’, ‘Siverskij’, ‘Signal’, ‘Utro’, ‘Ûna’) and ‘Аlyj Parus’ breeding clone had regeneration rate above 40%. The regeneration rate in the studied subset was genotype independent according to the ANOVA results (p=0.711). Viability and regeneration rate were significantly correlated (r=0.86). As a result of the experiments, explants of 14 modern cultivars and two breeding clones with the known post-thaw regeneration rate were successfully cryopreserved in the VIR cryobank. Four cultivars (‘Grand’, ‘Gusar’, ‘Signal’, ‘Utro’) were monitored for their regeneration capacity after the long-term (seven months) preservation in the VIR cryobank. On an average, these four cultivars demonstrated a post-thaw regeneration capacity of 41.8%. It can be concluded that the use of the modified method of droplet vitrification is relevant for increasing the VIR potato cryo-collection

Resistance to causal agents of late blight and golden potato nematode of the modern cultivars of seed potatoes and their phytosanitary status in various agroclimatic zones of the European part of Russia

The active expansion of foreign potato cultivars on the territory of the Russian Federation has led to a change in the dominant pathogen species and to the emergence of new pathotypes of causal agents of harmful potato diseases. The aim of the study was to evaluate resistance to Phytophthora infestans and Globodera rostochiensis of modern potato cultivars and determine the distribution of fungal and oomycetic diseases on potato cultivars in various agroclimatic zones of Russia. The resistance of 41 foreign cultivars was evaluated to pathotype Ro1 G. rostochiensis and to isolate VZR17 P. infestans with virulence genes 1.2.3.4.5.6.7.8.9.10.11. Resistant to G. rostochiensis were 38 cultivars. 57R marker of the H1 gene conferring resistance to the Ro1 pathotype of G. rostochiensis was detected in 96.6 % of the nematode resistant cultivars studied; susceptible varieties did not possess this marker. Absolute resistance to the causative agent of late blight was demonstrated by the cultivars Alouette and Sarpo Mira (score 9); high levels of resistance (score 6 and 7) were determined for the cultivars Evolution, Red Fantasy and Ricarda. The cultivars Baltic Rose, Damaris, Desiree, Gala, Labella, Laperla, Mia, Sanibel, Zekura, Queen Anne, Red Lady and ‘7 for 7’ were classified as susceptible, although the characteristics of originators indicated average resistance to late blight. A phytopathological test was conducted on 92 samples of 39 varieties of seed potatoes from four federal districts of the Russian Federation: Volga, NorthWest, Central and North Caucasus. Rhizoctonia solani, Fusarium spp. and Helminthosporium solani are most common on all varieties. 100 % defeat of tubers by H. solani was recorded in various regions on the cultivars Red Scarlett, Evolution, Labella, Colombo, Gala and Nevsky. Widespread Colletotrichum coccodes on tubers of the elite and 2nd reproductions of the potato cultivar Red Scarlett (50.0–71.4 %) was recorded in the Central District

Potato resistance to quarantine diseases

The casual agent of potato wart Synchytrium endobioticum (Schilb.) Perc. and potato golden nematode (PGN) Globodera rostochiensis (Wollenweber) Behrens are the quarantine species causing the most widespread and destructive diseases of potato in the Russian Federation and other countries of the world. The potato pale nematode Globodera pallida (Stone) Behrens is not found in Russia, although in the European Union it is found everywhere. The review provides information on the harmfulness of S. endobioticum and PGN. To date, 43 pathotypes of S. endobioticum and 5 pathotypes of PGN have been revealed in the world. In the Russian Federation, only the first (D1) pathotype of potato wart and pathotype Ro1 of PGN have been found. Modern sets of differentials for S. endobioticum and PGN and methods of pathotype composition determination, including efforts to develop molecular markers (SSR) to determine the race of S. endobioticum, are presented. Data on the resistance of commercial potato cultivars to these quarantine diseases and methods for resistance determination are reviewed. Modern data on the genetics of potato resistance to S. endobioticum, G. rostochiensis and G. pallida, including mapping and cloning of R-genes, are presented. Available literature data on molecular markers of R-genes for marker assisted selection and the evaluation of their effectiveness are presented. The use of multiplex systems allows the presence of several genes for resistance to one or more pathogens to be analyzed at once. Mechanisms of potato quantitative resistance to S. endobioticum and PGN and adaptation processes in pathogens populations resulting in overcoming resistance of host are discussed. Cultivation of cultivars poorly susceptible to PGN can stimulate the adaptive variability of the pathogen and induce virulent pathotypes for 2–3 pathogen generations

Quarantine nematode species and pathotypes potentially dangerous for domestic potato production: populations diversity and the genetics of potato resistance

The review considers quarantine species and nematode pathotypes potentially dangerous for domestic potato production. Potatoes are affected by more than 30 types of parasitic nematodes, but the review focuses on the most harmful representatives of genera that cause great damage to potato production: Globodera, Ditylenchus, Nacob bus and Meloidogyne. Phytopathological and molecular methods of identification of species and pathotypes and the main achievements in studying the population variability of parasitic potato nematodes were analyzed. It was shown that due to the peculiarities of the life cycle of nematodes and lability of their genomes, the genetic variability of these organisms is very high, which creates a threat of forming new pathogenic genotypes of the parasites. The information about the intra- and interpopulation variability of nematodes is important for studying the ways of introduction and distribution of separate species, as well as for searching for the correlations of molecular markers with the pathotype. Phylogenetic studies based on modern data on genetic variability of populations have allowed to reveal species complexes in Globodera pallida (Stone) Behrens and Nacobbus aberrans (Thorne) Thorne & Allen (sensu lato), including cryptic species. The main components of successful protection preventing a wide distribution of parasitic nematodes are quarantine measures, agricultural techniques, biological methods of protection and cultivation of resistant cultivars. Special attention in the review is paid to the breeding of potato cultivars with durable resistance to various nematode pathotypes, because the cultivation of such varieties is the most ecologically safe and economically advantageous way to prevent epiphytoties. Currently, significant progress has been made in the genetic protection of potato cultivars, especially against cyst-forming nematodes. The review provides data on sources of potato resistance to parasitic nematodes identified in collections of wild and cultivated species. Data on identified R-gens and QTL of resistance that have been introduced into breeding varieties using different methods and approaches are analyzed. The literature data on the study of structural and functional organization of genes for resistance to potato cyst nematodes are given. The results of molecular research on revealing the polymorphisms of loci involved in the control of resistance to cyst and gall nematodes, the development of molecular markers of certain genes and their use in marker-assisted selection for developing of new resistant cultivars, including those with group resistance, are considered

New approaches to registration and conservation of domestic cultivars of berry crops in the VIR Genebank on the example of red raspberry and black currant

A collection of nomenclatural standards is being created at VIR for domestic cultivars of various crops in accordance with the International Code of Nomenclature for Cultivated Plants (ICNCP). A new complex strategy was proposed for vegetatively propagated crops for registering domestic cultivars received from their authors in the VIR genebank. In addition to the creation of nomenclature standards, the strategy includes the development of a genetic passport of a cultivar and the use of biotechnological methods to preserve explants (buds, meristems) isolated from plant material transferred by breeders to the VIR Herbarium. This approach can be used for any vegetatively propagated crop applying a protocol developed specifically for an individual crop. For raspberry and black currant varieties, the collecting of plant material, its preparation for the registration of nomenclature standards and the preservation of viable samples under controlled in vitro conditions have specific features. This article provides detailed protocols for performing the mentioned work for raspberry and black currant varieties. In addition, the article summarizes the first results of the implementation of our proposed strategy on the example of domestic raspberry and black currant varieties created in various breeding centers of Russia. Three years of joint work of VIR researchers and breeders from four breeding centers in five regions of the country have resulted in creation of nomenclature standards for 20 raspberry varieties, as well as for five black currant varieties bred at VIR. Thirteen samples of raspberry varieties and four of black currant varieties, genetically identical to nomenclature standards, were introduced into in vitro culture; four raspberry cultivars have been placed in the VIR cryobank for the long-term cryopreservation