T. T. Efremova

Physics of seasonally ice-covered lakes: a review

Recently, the attention to the ice season in lakes has been growing remarkably amongst limnological communities, in particular, due to interest in the response of mid- and high-latitude lakes to global warming. We review the present advances in understanding the governing physical processes in seasonally ice-covered lakes. Emphasis is placed on the general description of the main physical mechanisms that distinguish the ice-covered season from open water conditions. Physical properties of both ice cover and ice-covered water column are considered. For the former, growth and decay of the seasonal ice, its structure, mechanical and optical properties are discussed. The latter subject deals with circulation and mixing under ice. The relative contribution of the two major circulation drivers, namely heat release from sediment and solar heating, is used for classifying the typical circulation and mixing patterns under ice. In order to provide a physical basis for lake ice phenology, the heat transfer processes related to formation and melting of the seasonal ice cover are discussed in a separate section. Since the ice-covered period in lakes remains poorly investigated to date, this review aims at elaborating an effective strategy for future research based on modern field and modeling methods.

The development of precise genetic stocks in two wheat cultivars and their use in genetic analysis.

SummaryThe results of genetic studies of common wheat that have been conducted in Novosibirsk, Russia, over the past 20 years by a research team are summarized. The research strategy was to develop a collection of aneuploids and substitution lines to be further used for chromosomal localization of genes and in the study of the genetic variability of wheat. On the basis of two cultivars, namely Saratovskaya 29 and Diamant, we have developed 6 sets of aneuploids with a complete set of monosomic lines for each, plus sets of lines ditelosomic and monotelosomic for “standard” arms. Exploiting the monotelosomics, 108 single chromosome intervarietal substitutions, 13 lines with alien substitutions (mono- and disomics) and 11 addition lines have been developed. A collection of lines isogenic for dominant marker genes of morphological characters has also been developed. The genetic collection was used in chromosomal localization of 15 genes, for many of which chromosome arms have been determined. Positively or negatively, the question of allelism within some loci has been answered.

Genetic analysis of glume colour in common wheat cultivars from the former USSR

Genotypes for the glume colour character have been studied in 27 cultivars of common wheat (Triticum aestivum L.) originated from old landraces, and 1 specimen of T. petropavlovskyi Udacz. et Migusch. by means of analysis of the F2 populations. The following tester lines have been used: white-glumed ‘Novosibirskaya 67’ ‘Diamant I’, and ‘Federation’, carrying the Rg1 gene alone; lines RL5405 and near-isogenic ‘Saratovskaya 29’ *5 (T. timopheevii Zhuk./T. tauschii (Coss.) Schmal.), carrying Rg2; line (1A ‘CS’ × ‘Strela’) with Rg3. The red glume colour in 21 cultivars of Triticum aestivum and in the accession of T. petropavlovskyi has been shown to be determined by the single gene Rg1, located on chromosome 1B. Five cultivars carrying the gene Rg3 for red glumes on chromosome 1A have been revealed. The cultivars ‘Zhnitsa’ and ‘Iskra’ carry the gene Rg3 alone. The red glume colour in the cultivars ‘Milturum 321’, ‘Milturum 2078’, ‘Sredneuralskaya’ is controlled by two genes, Rg1 and Rg3. In two common wheat cultivars, ‘Sarrubra’ and ‘Krasnoyarskaya 1103’ the red glume colour is determined by Rg1, inherited from local populations (‘Turka’ and ‘Kubanka’ respectively) of tetraploid wheat T. durum Desf. var. hordeiforme Host. Wide occurrence of the Rg1 gene in common wheat has been confirmed. On the contrary, none of the investigated varieties carries the gene Rg2.

Production of alloplasmic and euplasmic wheat-barley ditelosomic substitution lines 7H1Lmar(7D) and analysis of the 18S/5S mitochondrial repeat in these lines

Alloplasmic lines of common wheat with disomic substitution of chromosome 7D for telocentric chromosome 7H1Lmar of barley H. marinum subsp. gussoneanum Hudson were isolated from the plants of generation BC3, produced as a result of backcrossing of barley-wheat hybrids H. marinum subsp. gussoneanum (2n = 28) × T. aestivum (2n = 42), Pyrotrix, cultivar, with 28 common wheat cultivars Pyrotrix 28 and Novosibirskaya 67. Chromosome substitution pattern was determined using SSR analysis and C-banding. In preliminary genomic in situ hybridization experiments, telocentric chromosomes were assigned to wild barley was established. In the BC3F8 generations of three alloplasmic lines with the 7H1Lmar(7D) substitution type the differences in fertility manifestation were observed: most of the L-32(1) plants were sterile, in line L-32(2) only sporadic plants were sterile, and line L-32(3) was fertile. Simultaneously with these experiments, using selfpollinated progeny of the hybrids obtained in crosses of common wheat cultivar Saratovskaya 29 (2n = 41), monosomic for chromosome 7D, with common wheat cultivar Pyrotrix 28 with addition of pair of telocentric chromosomes 7H1Lmar (7D) of barley H. marinum subsp. gussoneanum, euplasmic wheat-barley ditelosomic substitution 7H1Lmar (7D) lines were isolated. The lines obtained had normal fertility. PCR analysis of the 18S/5S mitochondrial repeat (hereafter, mtDNA sequence) in alloplasmic and euplasmic ditelosomic substitution lines 7H1Lmar(7D) was performed. In the plants from alloplasmic sterile line L-32(1), the sequences only of the barley (maternal) type were revealed, while the plants from alloplasmic fertile lines L-32(2) and L-32(3) demonstrated heteroplasmy (the presence of barley- and wheat-like sequences within one individual). In euplasmic ditelosomic substitution lines the presence of only wheat-like 18S/5S mitochondrial repeat sequences was observed. The results indicate that the presence of barley-like mtDNA sequences in alloplasmic substitution lines was not associated with the presence of barley chromosomes in their nuclear genomes.

Effect of alien 5R(5A) chromosome substitution on ear-emergence time and winter hardiness in wheat-rye substitution lines

Ear emergence time and response to vernalization were investigated in 12 alien substitution lines in which a pair of chromosomes 5A of recipient spring wheat cultivars was replaced by a pair of chromosomes 5R of Siberian spring rye ‘Onokhoiskaya’. The recipients were 12 spring cultivars of common wheat, each carrying different Vrn genes. Spring rye ‘Onokhoiskaya’ had the Sp1 (now called Vrn-R1) gene for spring growth habit located on chromosome 5R, but its expression was weaker. The Vrn-R1 gene had no effect on growth habit, ear emergence time and response to vernalization in wheat-rye substitution lines. Ears emerged significantly later in the 5R(5A) alien substitution lines than in the recipient wheat cultivars with the Vrn-A1/Vrn-B1/vrn-D1 or Vrn-A1/vrn-B1/Vrn-D1 genotypes. No difference in ear emergence time was found between most of the 5R(5A) alien substitution lines and the cultivars carrying the recessive vrn-A1 gene. The presence of the Vrn2a and Vrn2b alleles at the Vrn2 (now called Vrn-B1) locus located on wheat chromosome 5B was confirmed.The replacement of chromosome 5A by chromosome 5R in wheat cultivars ‘Rang’ and ‘Mironovskaya Krupnozernaya’, which carries the single dominant gene Vrn-A1, converted them to winter growth habit. In field studies near Novosibirsk the winter hardiness of 5R(5A) wheat–rye substitution lines of ‘Rang’ and ‘Mironovskaya Krupnozernaya’ was increased by 20–47% and 27–34%, respectively, over the recurrent parents.

Genetic Analysis of Anthocyanin Pigmentation of the Anthers and Culm in Common Wheat

Anthocyanin pigmentation of various organs develops during plant ontogeny in response to adverse and damaging abiotic and biotic stressors (environmental factors). Using the monosome method, the genes responsible for anther and culm anthocyanin pigmentation (Pan1 and Pc2, respectively) were localized to 7D chromosome in introgressive lines from crosses between common wheat Triticum aestivum L. and the species Triticum timopheevii Zhuk. Genetic analysis of ten common wheat genotypes using testers carrying genes Pan1, Pc1 and Pc2 showed that these genotypes contained Pan1 and Pc2 genes. Visual examination of plants from 70 and 76 varieties of respectively winter and spring common wheat revealed anthocyanin pigmentation of anthers and culms in 36 varieties. Pan1 and Pc2 genes were presumably introduced into common wheat from Aegilops tauschii (Eig.) Tzvel., a donor of the D genome.

Resistance to Fungal Diseases in Hybrid Progeny from Crosses between Common Wheat Variety Saratovskaya 29 and the Amphidiploid Triticum timopheevii/Triticum tauschii (AAGGDD)

The progeny of BC6F2–4–BC9F2–4 has been analyzed for resistance to brown rust (Lr genes) and powdery mildew (Pm genes). This progeny was obtained due to introgression of the alien material from the synthetic hexaploid wheat Triticum timopheevii/Aegilops squarrosa (= Triticum tauschiiaAGGDD, 2n = 42) into the common wheat variety Saratovskaya 29. Against the background of natural infection, the lines resistant to both diseases and to either of them were developed. The brown-rust and powdery-mildew resistance is controlled by one/two effective independent genes Lr and Pm.

A cytogenetic study of the blue-grain line of the common wheat cultivar Saratovskaya 29

The chromosome composition of the blue-grain line i:S29Ba of the cultivar Saratovskaya 29 was identified by cytological, GISH, and microsatellite analyses and C-banding. It was found that common wheat chromosome 4B of the cultivar Saratovskaya 29 was substituted with the Agropyron elongatum Host. chromosome carrying the gene for blue grain (s:S294Ag(4B)) during the construction of this nearly isogenic line. The blue-grain line was tested for productivity. The substitution of total chromosome 4B of the cultivar Saratovskaya 29 by Ag. elongatum chromosome 4 did not significantly affect the spike productivity parameters and grain quality with the exception of spike length (plus effect), spike density, and vitreousness (minus effects). The blue-grain line with s:S294Ag(4B) can be used in further studies associated with chromosome engineering in cereals and wheat breeding.

The influence of Vrn-B1a and Vrn-B1c alleles on the length of developmental phases of substitution and near-isogenic lines of common wheat

The influence of Vrn-B1a and Vrn-B1c alleles on the length of developmental phases in lines of winter cv. Sava with intervarietal substitution of chromosomes 5B and near-isogenic lines (NILs) with these loci in the genetic background of winter cv. Bezostaya 1 is studied. We have confirmed, that effects of Vrn genes appear on the tillering phase and that the response to vernalization and shortening of day length can change the duration of this phase. We have shown that after vernalization and under short-day conditions the Vrn-B1a allele has the strongest effect on the length of the tillering phase. After vernalization in late substitution line Sava (Diamant II 5B) with the Vrn-B1a allele length of the tillering had decreased 6 days stronger, than in the earlier line Sava(Saratovskaya 29 5B) with the Vrn-B1c allele. After shortening of the day length in late NIL i:Bez1Vrn-B1a the length of the tillering phase and of period “stem elongation—heading” had increased stronger, for 13 and 5 days, respectively, than in the early i:Bez1Vrn-B1c line. The study of F1 hybrids between substitution and isogenic lines, the growth habits of which are determined by both Vrn-B1a and Vrn-B1c alleles, had shown the dominance of the trait lateness, which is determined by the Vrn-B1a allele. In F1 hybrids between substitution lines, the length of tillering was similar to that of the line with Vrn-B1a allele, and in F1 hybrids between NILs, the length of tillering was intermediate between parental lines.

The role of chromosomes from homeologous group 5 in regulation of grain hardness and protein content in substitution lines of common wheat cultivar Saratovskaya 29

Genetic regulation of grain hardness and protein content in intervarietal substitution lines for chromosomes of homeologous group 5 was examined. Common wheat cultivar Saratovskaya 29 with high bread-backing properties served as the recipient. Donors of chromosomes 5A and 5D were 18 cultivars with variable traits examined, including high-protein cultivars (Atlas 66 and Diamant 2), and soft-grain cultivars (Ul’yanovka and Chinese Spring). Analysis of substitution lines pointed to a substantial effect of chromosome 5D on the regulation of both traits. It was demonstrated that as a result of intervarietal substitution for chromosome 5D from donor cultivars Ul’yanovka and Chinese Spring, the endosperm softness was increased compared to the recipient cultivar Saratovskaya 29. Substitution lines Saratovskaya 29/Atlas 66 5D and Saratovskaya 29/Diamant 2 5D were characterized by high grain protein content, as well as by high endosperm hardness. In addition, the line Saratovskaya 29/Novosibirskaya 67 5D, characterized by grain hardness higher than in Saratovskaya 29, was isolated. In the lines with intervarietal substitution of chromosome 5A, grain protein content was found to be lower than in recipient cultivar Saratovskaya 29.