Theoretical aspects of heterosis

The phenomenon of heterosis, known as superior performance of hybrid organism compared with either of 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 experimental data obtained from the study of maize hybrids, and mathematical calculations, some genetic models have been proposed to explain heterosis from various types of gene interaction, such as dominance, over-dominance and epistasis. However, any of the proposed concepts has weak points, which place limitations on the possibility of overall interpretation of heterotic response in F1. In this review we gather a brief account of findings from various studies for critical evaluation of the main theoretical concepts based on the information accumulated to date by genetics and molecular biology and focused on particular mechanisms acting for specific traits. We discussed some aspects concerning the role of mutation loads in the formation of heterotic phenotype. Also, we gathered a brief account of findings for interpretation of genetic effects due to linkage and non-allelic genes’ interactions that make nuances to analysis of dominance and over-dominance. We have provided information about combining ability, its practical application in the context of the concept of heterotic groups. Here we also discussed some aspects of “genotype–environment” interaction. Recent advancements in genetics and molecular biology indicate the importance of various types of gene action for heterosis and confirm the necessity of systemlevel approaches to understanding this unique phenomenon

Mineral composition of bread wheat lines with introgressions of alien genetic material

Background. Modern bread wheat (Triticum aestivum L.) cultivars developed mainly to increase productivity often contain low concentrations of minerals in their grain. Wild and primitive wheats demonstrate rich genetic diversity, including the content of minerals in the grain, and can be used to improve the wheat gene pool for this trait. The aim of this work was to study the mineral composition in the grain of bread wheat lines with introgressions of the genetic material from Triticum L. spp.Materials and methods. We studied parental spring bread wheat cultivars, accessions of tetraploid and hexaploid Triticum spp., and 20 introgressive lines obtained on their basis in 2018 and 2020. Concentrations of macro- (K, P, Ca, and Mg) and micronutrients (Zn, Fe, Cu, and Mn) were measured using atomic emission spectrometry with inductively coupled plasma, and total protein content in wheat grain according to GOST 10846-91. The data were processed using the Statistica 10.0 and MS Excel software packages.Results and conclusion. The content of minerals in the grain of Triticum spp. was higher than in T. aestivum cultivars (the twoyear average difference was 1,02 to 2,13-fold, depending on the studied mineral). Most of the lines with alien genetic material exceeded their parent bread wheat cultivars in Zn, Fe, Cu and Mn content and came close to them in the levels of N, P, Mg and K. ANOVA established a statistically significant impact of the genotype, environment, and genotype × environment interaction on the variation of the grain macro- and micronutrient content. Lines with a consistently high concentration of grain minerals and high productivity were identified. These lines are of interest for wheat breeding for grain quality

SSR loci potentially associated with high amylopectine content in maize kernel endosperm

As a component of functional nutrition, maize cultivars with “non-traditional” kernel composition (waxy, oilbearing, sugar, opaque, etc. phenotypic variants) are promising. Mutations in the waxy gene, which break down the structure and function of the enzyme for amylose biosynthesis, lead to a waxy (with a high content of amylopectin) endosperm formation. High variability of the waxy gene limits the use of microsatellite loci in marker associated selection of waxy maize genotypes. The increased frequency of gene rearrangements within the waxy locus facilitated the origination of many high-amylopectin corn lines carrying different SSR allelic variants. The purpose of this study was to evaluate the effectiveness of using waxy locus microsatellite sequences for identification and labeling of waxy maize genotypes. To this end, a complex of biochemical (calorimetry, bichromate method), molecular-genetic (SSR-PCR, capillary gel electrophoresis with fluorescent detection of fragments) and statistical (descriptive statistics, cluster analysis, χ2) analysis methods was used. Plant material used were 33 samples of corn kernels including mutant forms with a high content of amylose, amylopectin, short-chain starches, were kindly provided by VIR genetic collection (Russian Federation) and Maize Genetics Cooperation Stock Center (USA). The contents of starch, short-chain soluble carbohydrates, amylose, amylopectin in the grain of 33 maize samples were evaluated. Compositionally similar (to endosperm carbohydrates content) groups of samples were identified. They include 13 high-amylopectin samples carriers of waxy (wx) gene mutations and 20 samples with wild-type character (Wx). Molecular genetic screening of the collection included an analysis of the polymorphism of the microsatellite loci phi022, phi027, phi061 associated with the waxy gene sequence. Allelic composition of individual loci and their combinations were analyzed in relation to the accumulation of reserve carbohydrates in the kernel endosperm. Only the analysis of the phi022/phi027 combination or all three markers in the complex allows differentiating the wild Wx and mutant wx phenotypes of maize. It was shown that not the individual allelic polymorphisms of the phi022, phi027, phi061 loci are efficient for the markerassociated selection of high-amylopectin maize, but their unique combinations

Marker-assisted identification of maize genotypes with improved protein quality

Currently, more than 70 % of maize is used for food and fodder; therefore, grain quality improvement can increase its nutritive and energy value. 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 identification of 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 maize breeding efficiency. We collected 54 maize genotypes differing in grain quality performance. Amplification with three specific markers to the opaque-2 gene (phi057, phi112 and umc1066) revealed homozygous recessive o2 genotypes, associated with 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 starchy endosperm of o2 mutant to the hard vitreous phenotype. The selected QPM accessions are of interest for maize breeding programs aimed at grain quality improvement. The use of the markers to o2 and modifier genes accelerates the development of QPM varieties and significantly reduces the labor and financial costs of their production

Some aspects of gene association with high sport achievements

Most papers on sport genetics identify differences between genotypes of athletes and a control group. It is obvious that the genetic differences should also be among sportsmen with different qualifications. Additionally, athletes’ performance depends not only on their genotypes, but also on the gene activities, which can be different during the training process in various athletes.The aim of the study was to compare genotypes of athletes with different qualifications and to analyze the change in expression of some genes responsible for the physical performance. Genotypes of 143 elite sportsmen of 18 national teams were analyzed by PCR method. A comparison of the genotypes of Masters of Sports, International Masters of Sports and Honored Masters of Sports showed that the frequencies of favorable gene variants were higher in the genotypes of more qualified athletes; it proves an appropriate genetic potential necessity for high achievements in sports. The analysis of UCP2, HIF1A and MTHFR gene expression changes in response to two-week hypoxiс training was performed on 15 skaters of high qualification. We found that average UCP2 and MTHFR mRNA levels had significantly increased after the training but the expression of the HIF1A gene had reduced. At the same time, individual athlete variability in UCP2, HIF1A and MTHFR gene expression was revealed. Genotype influence on gene expression was shown with the help of the UCP2 gene – its activity was higher in sportsmen with Val/Val than with Val/Ala or Ala/Ala genotypes. Consequently, genotyping and analysis of gene expression is very important for athlete selection and training

Molecular-genetic mechanisms underlying fruit and seed coloration in plants

Diverse patterns of plant fruit and seed coloration are determined by the presence of two main types of pigment, carotenoids (red, orange and yellow color) and anthocyanins (purple, blue, red). Thеy belong to two groups of secondary metabolites, isoprenoids and flavonoids. Interest towards the genetic mechanisms that control coloration in plants has recently increased due to the antioxidant and antimicrobial properties of some pigments and their colorless precursors consumed with plant-derived food. The genes encoding enzymes involved in step-bystep conversion of initial organic molecules to final pigmented compounds are referred to as structural genes, while regulatory genes are responsible for activation of the expression of structural genes and control the synthesis of pigments at certain times and in proper tissue. The data in plant genetics accumulated to date show that the inter- and intraspecies phenotypic diversity in coloration is mainly related with regulatory genes. Previously developed rich gene collections and precise genetic models for coloration traits in dicots and monocots as well as the rapid development of molecular genetic methods for studying plants allowed for studying genetic regulation of pigment synthesis at a molecular level. The peculiarities of the regulation of carotenoid biosynthesis are exemplified with Solanaceae fruits. The genetic mechanisms underlying the synthesis of various flavonoid pigments are exemplified with a study of seed color in Poaceae plants. In summary, prospects for the practical use of regulatory genes that control pigment synthesis are discussed and examples of their practical use in vegetable and cereal crop breeding are given

ОЦЕНКА ЭФФЕКТИВНОСТИ ДНК-МАРКЕРОВ В СЕЛЕКЦИИ ПО БИОХИМИЧЕСКИМ ПРИЗНАКАМ КАЧЕСТВА КЛУБНЕЙ КАРТОФЕЛЯ

Validation of 8 allele-specific markers associated with potato tuber quality traits (starch content and chip quality) was performed in tetraploid breeding populations of the Belarusian selection. The possibility of the DNA-based marker application for selection of genotypes with better tuber quality traits is shown.На примере тетраплоидных межвидовых гибридов белорусской селекции рассмотрена возможность применения восьми ДНК-маркеров в селекции картофеля по биохимическим признакам качества (содержанию крахмала и качеству хрустящего картофеля). Показана возможность отбора ценных генотипов на основе применения ДНК- маркеров, ассоциированных с высокой крахмалистостью и качеством хрустящего картофеля

Качество зерна у линий мягкой пшеницы T. aestivum с интрогрессией генетического материала T. dicoccoides и T. dicoccum

Related wild and cultural wheat species are regularly involved for expanding T. aestivum genetic diversity because they contain many valuable genes. We evaluated the effect of the genetic material of tetraploid species of the genus Triticum (T. dicoccoides, T. dicoccum) on the grain quality of introgression lines of spring bread wheat. The composition of the high molecular weight glutenin subunits which play an essential role in the formation of wheat baking properties was identified in the introgression lines of bread wheat and their parental forms. The traits of grain quality (hardness, protein and gluten content, gluten quality) were also evaluated. The lines with Glu-1 loci alleles from wheat relatives T. dicoccoides and Т. dicoccum were selected. It was found that the introgression of alien genetic material into the common wheat genome had a positive effect on the parameters of grain quality such as hardness, protein and gluten content. The lines with Glu-A1 loci alleles from T. dicoccoides and Glu-B1 from T. dicoccum were at the level of a parent wheat variety or of a higher gluten quality. As a result of the research, the new lines of bread soft wheat with high grain quality were found and can be used in the crop breeding.Дикорастущие и культурные сородичи T. aestivum, которые являются источниками многих хозяйственно ценных генов, часто привлекаются для расширения генофонда пшеницы. Оценено влияние генетического материала тетраплоидных видов рода Triticum (T. dicoccum и T. dicoccoides) на качество зерна интрогрессивных линий яровой мягкой пшеницы. У линий с генетическим материалом T. dicoccum и T. dicoccoides в сравнении с родительскими формами проведена идентификация состава высокомолекулярных субъединиц глютенина, связанных с хлебопекарными свойствами зерна, с одновременной оценкой качества зерна по показателям: стекловидность, содержание белка, массовая доля и качество клейковины. Выделены линии с аллелями локусов Glu-1 от тетраплоидных сородичей пшеницы T. dicoccoides и Т. dicoccum. Установлено, что интрогрессия чужеродного генетического материала в геном мягкой пшеницы оказала положительный эффект на такие признаки качества зерна, как стекловидность, содержание белка и клейковины. Линии с аллелями локусов Glu-А1 от T. dicoccoides и Glu-В1 от Т. dicoccum были на уровне исходного сорта пшеницы или превосходили его по качеству клейковины. В результате проведенных исследований выделены новые линии яровой мягкой пшеницы с высоким качеством зерна, которые могут использоваться для селекции данной культуры

ИСПОЛЬЗОВАНИЕ МОЛЕКУЛЯРНЫХ МАРКЕРОВ ДЛЯ СОЗДАНИЯ ЛЕЖКИХ ГИБРИДОВ ТОМАТА С ВЫСОКИМ СОДЕРЖАНИЕМ КАРОТИНОИДОВ

A collection of tomato genotypes was tested by functional PCR markers for the genes determining a carotenoid content and a period of fruit preservation. Identified as a result of DNA-typing sources of breeding the valuable genes were used for high carotene content line crossing and long-storage testers according to the top-cross scheme. The combining ability of lines and testers on the basis of “mass concentration of β-carotene” features was studied and the specimens with a high concentration of β-carotene and lycopene were selected.Протестирована коллекция томата с применением функциональных ПЦР маркеров к генам, детерминирующим содержание каротиноидов и период сохранности плодов. Выделенные в результате ДНК-типирования источники селекционно-ценных генов использовались в  скрещивании высококаротиновых линий и лежких тестеров по схеме топкроссов. Изучена комбинационная способность линий и тестеров по признаку «массовая концентрация β- каротина», выделены образцы с высоким содержанием β-каротина и ликопина

ОЦЕНКА ПОЛИМОРФИЗМОВ ГЕНОВ LcyE И CrtRB1, АССОЦИИРОВАННЫХ С ПОВЫШЕННЫМ УРОВНЕМ ПРОВИТАМИНА А В ЗЕРНЕ КУКУРУЗЫ (ZEA MAYS L.), В КОЛЛЕКЦИИ ОБРАЗЦОВ РАЗЛИЧНОГО ЭКОЛОГО-ГЕОГРАФИЧЕСКОГО ПРОИСХОЖДЕНИЯ

The collection of 54 maize samples of different eco-geographical origin was evaluated for the key polymorphisms of the LcyE and CrtRB1 genes (LcyE 5′TE, LcyE 3′Indel and CrtRB1 3′TE) associated with the provitamin A content in maize grain. Favorable alleles of LcyE were not detected in the studied material. Selected genotypes with favorable allele 1 of СrtRB1 3′TE functional marker (35 % of the samples) are of interest for maize breeding programs aimed at improving the grain quality.Проведена оценка ключевых полиморфизмов генов LcyE и CrtRB1, ассоциированных с повышенным уровнем провитамина А в зерне кукурузы (LcyE 5′TE, LcyE 3′Indel и CrtRB1 3′TE), в коллекции из 54 образцов различного эколого-географического происхождения. В изученном материале не выявлено присутствия благоприятных аллелей гена LcyE. Выделены генотипы (35 % образцов), несущие благоприятный аллель 1 функционального маркера СrtRB1 3′TE, которые представляют интерес для селекционных программ кукурузы, направленных на повышение качества зерна