L. V. Khotyleva

Genetic Polymorphism Evaluation of Spring Triticale (×Triticosecale Wittmack) Samples with Use of RAPD and ISSR Markers

The molecular genetic heterogeneity of 20 spring triticale samples was studied. The use of ISSR and RAPD markers revealed a high polymorphism level of 80.2 and 89.9% on average, respectively, which allowed grouping the samples according to their genetic relations; it also became possible to select parental pairs for crossbreeding and acquisition of hybrids with heterotic vigor.

Association between Total Carotenoid Content of Maize Kernels ( Zea mays L.) and Polymorphic Site INDEL1 in PSY1 Gene

Maize is the only major cereal crop that can naturally accumulate appreciable levels of carotenoids which are the source of provitamin A. The association of the total carotenoid content in maize kernels with allelic variation PSY1 InDel1 was estimated. We used a collection of 54 maize genotypes of different ecogeographical origins, methods of PCR analysis, spectrophotometry, and statistical analysis in this study. The total carotenoid content of genotypes with a favorable allele of InDel1 is 0.60 mg/100 g, which is significantly higher than that of the samples with an unfavorable allele (0.43 mg/100 g). Thus, the use of PCR-based markers for PSY1 InDell polymorphism is a reliable method for identifying genotypes with high carotenoid accumulation in maize kernels.

Features of chromosome behavior in meiosis in common wheat lines containing genetic material of tetraploid wheat species

The study of meiotic chromosome behavior in hybrid lines obtained by crossing common wheat with tetraploid wheat species shows that the introgression of alien genetic material into the common wheat genome does not have a negative effect on its meiotic stability. Aberrant cells are few not only in the metaphase but also at the final stage of the tetrads. The variation in the level of cytological stability between the studied lines stems from differences in the number and localization of tetraploid wheat genome fragments in the hybrid genome. The influence of the cytoplasm on the formation of the karyotype of wheat introgression lines has been detected.

Theoretical aspects of heterosis

The phenomenon of heterosis, known as the superior performance of hybrid organisms over their parents, has been exploited by agricultural practices in the production of various crops since the beginning of the last century; however, its genetic basis has remained obscure. With the experimental data obtained from the study of maize hybrids and mathematical calculations, some genetic models have been proposed to explain heterosis in terms of various types of gene interaction, such as dominance, overdominance, and epistasis. However, each of the proposed concepts has weak points, which impose limitations on the possibility of the overall interpretation of the heterotic response in F1. This review provides a critical assessment of the theoretical concepts of heterosis from the perspective of the currently accumulated data of genetics and molecular biology, which are focused on specific mechanisms acting for specific traits. In particular, the role of lethal and semi-lethal mutations in the formation of a heterotic phenotype in plants is shown. The issues of the interpretation of genetic effects in case of gene linkage, which are referred to as pseudo-overdominance, are considered. Particular attention is paid to nonallelic interactions of genes, which add new nuances when discussing the effects of dominance and overdominance. Information on combining ability and its practical use in the context of the concept of heterotic groups is presented. Some aspects of the genotype–environment interaction are shown. The analysis of the theoretical concepts of heterosis from the perspective of modern genetic data testifies to the important role of various types of gene action in the formation of an outstanding phenotype and confirms the need for a systematic approach to this complex and unique phenomenon.

Marker-assisted identification of maize genotypes with improved protein quality

Currently, more than 70% of maize is used for food and fodder; therefore, an improvement in grain quality can increase its nutritive and energy value. A deficiency of two essential amino acids (lysine and tryptophan) significantly reduces the nutritional quality of maize proteins. However, in comparison to conventional maize varieties, opaque2 (o2) mutants have greater contents of lysine and tryptophan in their endosperm proteins and their bioavailability is better. The aim of the study was to identify the maize accessions with high-quality protein. A collection of maize accessions of various ecogeographical origins was studied by molecular methods. This approach was expected to improve the maize’s breeding efficiency. We collected 54 maize genotypes differing in grain quality performance. Amplification with three specific markers for the opaque-2 gene (phi057, phi112, and umc1066) revealed homozygous recessive o2 genotypes associated with an improved nutritional quality of the protein. UREA-PAG electrophoresis of zein proteins was used for Quality Protein Maize (QPM) identification. In addition to the mutant o2 allele, QPM contains genetic modifiers that convert the starchy endosperm of the o2 mutant to the hard vitreous phenotype. The selected QPM accessions are of interest for maize breeding programs aimed at improving grain quality. The use of the markers for o2 and modifier genes accelerates the development of QPM varieties and significantly reduces the labor and financial costs of their production.

Molecular cytogenetic analysis of triticale and wheat lines with introgressions of the genetic material of triticeae tribe species

A number of problems associated with the necessity of creating forms that are characterized by resistance to diseases, pests, and unfavorable environmental conditions exist in the selection of cultivated cereals. The expansion of the genetic diversity by the genes for resistance to biotic and abiotic stresses is reached by the use of the gene pool of wild and cultural common wheat relatives. In order to improve cereals by a number of economically valuable traits, the hybrid lines of the common wheat (T. aestivum/T. durum and T. aestivum/T. dicoccoides), as well as the triticale lines from the crossing between hexaploid triticale varieties and genome-substituted common wheat forms (in which the D genome is substituted for diploid Aegilops genomes), were obtained by the remote hybridization method. The aim of the study was to identify the lines of common wheat and hexaploid triticale with alien introgressions and to estimate their cytological stability by means of cytological and molecular genetic analyses. The use of the comparative analysis of the chromosome structure by the GISH and FISH methods, microsatellite and chromosome-specific markers for the triticale line genotyping allowed us to establish that the genome reorganization, which includes both introgression of the alien material and the common wheat chromosome rearrangement (resulting in new combinations of the genetic loci), occurs in the process of triticale hybridization with genome-substituted common wheat forms. The efficiency of using microsatellite markers developed on the base of the common wheat genome was demonstrated for the characterization of the T. aestivum/T. durum and T. aestivum/T. dicoccum lines created as a result of interspecific hybridization. From 4 to 12 translocations of different length from the T. durum, T. dicoccum were found in the chromosomes of the A and B genomes of the studied hybrid lines. The meiotic stability was detected in the studied hybrid triticale and wheat material; this created the preconditions for the preservation of alien introgressions in a number of the following generations.

The impact of parental genetic divergence on the heterosis of F1-hybrids of spring triticale

Molecular heterogeneity was studied in 20 spring triticale accessions using ISSR- and RAPD-markers, which allowed the studied material to be grouped according to the degree of genetic relationship and to choose genetically distant parental pairs for crosses to obtain heterotic hybrids. Expression of the heterosis of F1 triticale hybrids was studied. Evaluation of the degree of parental genetic divergence on the heterosis level of the F1-hybrids revealed that increased genetic distance values between parental components leads to a higher probability of obtaining heterotic hybrids.