Hybrid dwarfness in crosses between wheat (Triticum aestivum L.) and rye (Secale cereale L.): a new look at an old phenomenon.

The existence of hybrid dwarfs from intraspecific crosses in wheat (Triticum aestivum) was described 100 years ago, and the genetics underlying hybrid dwarfness are well understood. In this study, we report a dwarf phenotype in interspecific hybrids between wheat and rye (Secale cereale). We identified two rye lines that produce hybrid dwarfs with wheat and have none of the hitherto known hybrid dwarfing genes. Genetic analyses revealed that both rye lines carry a single allelic gene responsible for the dwarf phenotype. This gene was designated Hdw-R1 (Hybrid dwarf-R1). Application of gibberellic acid (GA3 ) to both intraspecific (wheat-wheat) and interspecific (wheat-rye) hybrids showed that hybrid dwarfness cannot be overcome by treatment with this phytohormone. Histological analysis of shoot apices showed that wheat-rye hybrids with the dwarf phenotype at 21 and 45 days after germination failed to develop further. Shoot apices of dwarf plants did not elongate, did not form new primordia and had a dome-shaped appearance in the seed. The possible relationship between hybrid dwarfness and the genes responsible for the transition from vegetative to generative growth stage is discussed.

[Genetics of postzygotic reproductive isolation in plants].

Postzygotic reproductive isolation, based on negative interactions of genes, is a key aspect of divergent speciation in plants and animals. The effect of the interaction manifests as a drastic reduction in fitness of hybrids of the first and subsequent generations, which is expressed as hybrid lethality, weakness or sterility. Both simple genetic control of genetic incompatibility, which includes interallelic negative complementation or epistatic interactions of a limited number of genes, and more complex control, based on epistatic interactions of many genes, have been described in plants. It is thought that genes for reproductive isolation are nonuniformly distributed over the genome and are related to differential adaptation. The mosaic organization of the genomes in this respect provides restoration of their structural and functional integrity upon interspecies hybridization in natural conditions. Many cultured and wild plant species, in contrast to animals, were found to be polymorphic at genes controlling interspecies incompatibility. This fact facilitates genetic analysis of incompatibility and broadens perspectives in studying the structure, functions, and molecular evolution of the genes controlling postzygotic reproductive isolation, in view of the possible leading role of these genes in adaptive speciation.

[Genetic control of embryo lethality in crosses between common wheat and rye].

The phenotypic manifestation and genetic control of embryo lethality observed in crosses between common wheat and rye were studied. It was found that crosses between common wheat and inbred self-fertile rye lines L2 and 535 gave rise to ungerminating grains, in which the development and differentiation of the hybrid embryo are arrested. Study of the degree of embryo development in the hybrid grains obtained by crossing common wheat varieties with inbred rye lines L2 and 535 showed that genotypes of the parents affected the ratio between undifferentiated embryos of various sizes. Analysis of this trait was performed by test crosses according to a novel pedigree program with the use of interlinear hybrids and a set of fourth-generation hybrid recombinant inbred lines. Rye line L2 was shown to bear the Eml (Embryo lethality) gene, which terminates the development of the hybrid embryo in amphihaploids. The suggestion of complementary interaction between wheat and rye genes during formation of a "n ew" character in wheat-rye F1 hybrids is discussed. A method of detecting an allele not complementary to the rye Eml allele in wheat is proposed. The proposed test program allows appropriate study of the system of wheat and rye genes involved in complementary interaction in the genotype of a distant hybrid.

[The effect of genotypes of parental rye lines on the development of quantitative traits in primary octoploid Triticale: spike fertility]. / Analiz vliianiia genotipa roditel'skikh linii rzhi na formirovanie kolichestvennykh priznakov u pervichnykh oktoploidnykh tritikale. Fertil'nost' kolosa.

The number of seeds and seed setting in the main spike were studied in primary octoploid triticale obtained from crosses between the common wheat cultivar Chinese Spring and 66 inbred rye lines. In some rye lines, the mutations of self-fertility were identified in the S, Z, or T incompatibility loci. The number of seeds was determined under controlled self-pollination of the main spike. In the set of triticale examined, each trait exhibited high variation. Hence, the rye lines were suggested to carry gene alleles both increasing and decreasing these traits in triticale. All the traits studied were significantly influenced by environmental conditions. Ten triticale lines were identified, which had the largest seed setting under self-pollination. Seven out of ten samples with the high number of seeds carried mutations in the T locus and in the three samples, the unidentified self-fertility mutations were present. The triticale lines with mutations in the S and Z loci displayed much lower self-fertility on average. The ways and means of identifying and mapping the rye gene responsible for distinctions between the triticale quantitative traits are discussed.

[Epidemiological situation on tularemia in the regions of Stavropol Territory affected by flood]. / Epidemiologicheskaia situatsiia po tuliaremii v raionakh Stavropol'skogo Kraia, podvergshikhsia navodneniiu.

The data obtained in the analysis of the epidemiological situation in tularemia in the zone of inundation in the Stavropol Territory in 2002 are presented. The current systematic epidemiological surveillance, as well as the data of urgent epizootological and epidemiological survey in the zone of inundation permitted the objective prognostication of the situation in tularemia and formed the basis for the rational planning and realization of prophylactic measures.

[Gene typing of infectious tularemia strains isolated from the Stavropol and Krasnodar Territories]. / Genotipirovanie shtammov vozbutelia tuliaremii, vydelennykh na territoriiakh Stavropol'skogo i Krasnodarskogo Kraev.

The typing of F. tularensis strains by four variable number of tandem repeats (VNTR) loci has been carried out. Among the strains isolated in the Stavropol and Krasnodar Territories seven genotypes have been detected and their spread in different natural foci has been analyzed. The data thus obtained suggest that the VNTR analysis may become an important instrument for studying the structure of the natural foci of tularemia and evolutionary relationships between individual areas of these foci.

[Epizootic significance of white-toothed shrews in the natural focus of steppe type tularemia in the Stavropol' region]. / Epizooticheskoe znachenie zemleroek belozubok v prirodnom ochage tuliaremii stepnogo tipa v Stavropol'skom krae.

The observations indicate that anthropogenic activities cause structural changes with time among tularemia pathogen carriers in the microfocus. The epizootic and epidemic values of animal species, such as dwarf hamsters and house mice, decrease while those of insect-eating animals, namely white-toothed shrews that refer to Group II increase, in terms of tularemia infection susceptibility. In white-toothed shrews, tularemia infection rates are 4-6-times greater than those in other small mammals that refer to Group I.

[Role of some wild birds and mammals in the natural foci of Crimean haemorrhagic fever in Stavropol' region]. / Rol' nekotorykh dikikh ptits i mlekopitaiushchikh v prirodnoi ochagovosti krymskoi gemorragicheskoi likhoradki v Stavropol'skom krae.

The results of the study on the role of some wild mammals and birds as feeding sources of for ticks Hyalomma marginatum, the main vectors of Crimean haemorrhagic fever virus in the Stavropol Territory, in the preimago phases of their development are presented. These phases (larvae and nymphs) were found on rooks, hooded crows, partridges, European brown hares and eared hedgehogs. The examination of domestic fowl resulted in finding larvae and nymphs in small amounts on turkeys. According to the data of the epizootological survey carried out in summer and autumn of 2000 in the Stavropol Territory, rooks and, to a lesser extent, hares were found to be the main feeding sources for ticks in the preimago phases. Rodents seemed to be of minimal importance as feeding sources under the conditions of the Stavropol Territory. Of all animals, rooks must be the main object in the epizootological survey of the territory.

[Specialized epidemic brigade during extreme situation]. / Iz opyta raboty spetsializirovannoi protivoépidemicheskoi brigady v ekstremal'nykh usloviiakh.

Information on the main trends in the activity and on the organization of the work of the specialized antiepidemic brigade of the Stavropol Research Institute for Plague Control in Grozny in the first half of the year 2000 is presented. At the initial stage of this activity the specialists of the brigade were entrusted with all functions of the local state sanitary and epidemiological service which had lost its qualified personnel and material resources. At the initial stages of the work the main attention was drawn to the organization of the registration of patients with infectious diseases, to the control of drinking water and to the realization of immunoprophylactic measures, etc. The specialists of the brigade carried out their work in close cooperation with the medical service of the Territorial Head Office of the Ministry of Emergency Situations of the Russian Federation in the Chechen Republic.

[On the sanitary-hygienic state of the drinking water supply facility and the organization of the sanitary and bacteriological control of the water supply of the population of Grozny in recent years]. / O sanitarno-gigienicheskom sostoianii ob"ektov pit'evogo vodosnabzheniia i organizatsii sanitarnogo i bakteriologicheskogo kontrolia vodosnabzheniia naseleniia g.Groznyi v poslednie gody.

Information on the state of water supply in Grozny in the time of peace, during the armed conflict of 1994-1996 and at the period of the antiterrorist operation in the year 2000 is presented. In the year 2000 the centralized water supply of the population proved to be completely paralyzed. The quality of water brought to the city and water from the sources of decentralized water supply considerably deviated from the norm by its bacteriological characteristics. The control of the quality of drinking water supplied to the population was carried out only by the bacteriological laboratory of the specialized antiepidemic brigade.

[Comparative characterization of Vibrio cholerae O1, isolated from surface water reservoirs in Grozny in 1995 and 2000]. / Sravnitel'naia kharakteristika shtammov Vibrio cholerae O1, vydelennykh iz poverkhnostnykh vodoemov g. Groznyi v 1995 g. i 2000 g.

The results of complete identification revealed the phenotypical similarity of V. cholerae strains isolated from surface water reservoirs im Grozny in 1995 and 2000. The strains under study proved to be atoxigenic, hemolysis-positive and phage resistant. The modified method of subculturing from peptone water 1 to peptone water 2 was more labor-consuming, but it was used in the bacteriological laboratory of the specialized antiepidemic brigade with the aim of more profound study of open reservoirs for the presence of V. cholerae with the positive result.

[Outbreak of tularemia in the Republic of Dagestan]. / Vspyshka tuliaremii v Respublike Dagestan.

In Daghestan in the focus of the flood-plain swamp type 64 persons fell ill with tularemia in 1999. During the epizootological survey 8 Francisella tularensis strains were isolated from vectors and carriers and in 7 samples taken from open water reservoirs, as well as in 1 sample obtained from Ixodes ticks, tularemia antigen was detected. Humans were infected mainly by the transmissive route, as found in 71.8% of patients. 28% of patients were infected through contacts. The disease took mainly a mild course, registered in 95.6% of patients. The disease affected those persons who had not been immunized against tularemia.

[Taxonomic position and ecology of the causative agent of brucellosis isolated from murine rodents in regions of the northern foothills of the Greater Caucasus. II. The ecological and pathogenetic characteristics of Brucella strains isolated from murine rodents]. / Taksonomicheskoe polozhenie i ékologiia vozbuditelia brutselleza, vydeliaemogo ot myshevidnykh gryzunov v raionakh severnykh predgorii Bol'shogo Kavkaza. Soobshchenie II. Ekologicheskie i patogeneticheskie osobennosti shtammov brutsell, vydeliaemykh ot myshevidnykh gryzunov.

To establish the possibility of the circulation of brucellae among the population of myomorphous rodents, the mass survey of these rodents was carried out in the mountainous and foothill regions of the Caucasus. In the area of the northern foothills of the Caucasian Mountains 23 Brucella cultures were isolated from 2715 rodents under examination; these cultures proved to be similar to B. suis 1330 in respect to their pathogenicity and the character of pathomorphological changes induced in guinea pigs. Experiments on white mice demonstrated the possibility of brucellar contamination through sexual route and through feces.

[Comparative evaluation of the spectrum of lytic effects of bacteriophages TB, Wb, Fi, BK 2 and R on various Brucella species]. / Sravnitel'noe izuchenie spektra liticheskogo deistviia bakteriofagov TB, Wb, Fi, BK 2 i R na razlichnye vidy roda Brucella.

The lytic activity of Brucella phages TB, Wb, Fi, BK2 and R on various Brucella species has been studied. Phage TB has been found to lyse B. abortus, B. suis and B. neotoma, phage Fi has proved to be no different from phage TB, while phage Wb has shown higher activity in respect of B. suis; phage BK2 has been found to lyse B. abortus and, to a lesser extent, B. suis and B. melitensis; phage R has shown low activity, while splitting out phages capable of lysing B. abortus cultures in the S-form. All these phages multiply well in the corresponding indicator strains grown in Martin's broth. The Brucella cultures isolated from myomorphous rodents in the northern foothills of the Caucasus have been found to be similar to B. suis in respect to their spectrum of phage sensitivity, differing from B. suis only by forming smaller negative colonies in the presence of phage Wb.