Perennial grasses are the main plants in natural meadow phytocenoses of the middle, north, and steppes of Russia, and are also used to create seeded meadows and pastures in modern agriculture. The widespread distribution of cereal grasses is due to their valuable biological properties — ecological plasticity, high productivity, longevity, winter hardiness, and vegetative regeneration. When grown in single-species crops and in grass mixtures with a legume component, they provide low-cost and high-quality forage (green and conserved in the form of silage and hay) and are used for landscaping, recultivation, and soil protection from water and wind erosion [1].
Two of the most promising crops in the worldwide practice of grassland culture are perennial (Lolium perenne L.) and annual (Lolium multiflorum Lam.) ryegrass. On the basis of these species, more than 1000 cultivars have been created that are of great importance for fodder production and the development of animal husbandry in many countries [2].
In Russia, the share of perennial ryegrass within the total crop structure of perennial grasses is about 6% [3]. Most cultivars were obtained using methods of population genetics, in particular, methods of creating synthetic hybrid populations and polyploidy. Russian ryegrass cultivars are distinguished by longevity (up to 6 years with 4–5-fold mowing), winter hardiness, increased shoots, short vegetative shoots, high productivity of dry matter (up to 11 t/ha), seeds (up to 0.8 t/ha), Intensive breeding work is being carried out with the aim of increasing productive longevity, resistance to fungal diseases, and creating specialized cultivars that allow for growing in mixtures with legumes [4].
Different ryegrass species usually have a diploid set of chromosomes (2n = 2x = 14), however, improved tetraploid cultivars are common [2, 5]. The cross-pollination system results in high heterogeneity within species and in individual populations and cultivars [6]. In this regard, research on the study of the genetic diversity of a crop is of particular importance, as a result of which it is possible to identify promising material for breeding, significantly reduce the time for breeding new cultivars and ensure copyright protection of breeders.
With the introduction of modern DNA technologies, new opportunities have emerged to improve the accuracy of source evaluation and selection efficiency. Various types of PCR-based molecular markers are widely used to study representatives of the genus Lolium L. In particular, Bolaric et al. [6] analyzed 22 European cultivars of pasture ryegrass using RAPD markers and found a higher degree of genetic polymorphism within cultivars compared to the level of intervarietal differences. High intravarietal genetic variability (81.99%) was characteristic of 6 Chinese annual ryegrass cultivars when analyzed using microsatellites [7]. ISSR markers were found to be effective in assessing the genetic variability of 50 samples of different ryegrass species [8]. Using SRAP markers, the genetic polymorphism of annual ryegrass cultivars from the USA, China, and Denmark was studied with an average value of over 89% [9].
In recent years, the SCoT (start codon targeted polymorphism) technology has been successfully used to differentiate and identify species and cultivars of cereal grasses. The high variability of markers provides a special structure of 18-nucleotide primers designed to amplify sequences in the genome flanking the ATG start codon [10]. The main advantages of this technique are that the synthesis of primers does not require prior information about the sequence being investigated, markers are aimed at the functional regions of the genome, and the results are highly reproducible [11]. Using markers of this type, the genetic diversity of cat grass was studied (Dactylis glomerata L.) [12], as well as the phylogenetic relationships between 19 species of the genus Bromus L. [13]. Also, these markers were used for genotyping hybrids of reed fescue and Italian ryegrass [14].
In Russia, at the moment, forage grasses remain a poorly studied area of molecular genetic research. The breeding of this group of plants is based, in most cases, on the phenotypic labeling of natural genetic variations between and within ecotypes. This approach causes certain difficulties due to the great variability of traits and properties, the complexity of the genetic system, and a high degree of plasticity in the interaction of the genotype and environmental conditions. Until now, Russian ryegrass cultivars are distinguished exclusively by morphological characteristics, which are often similar, despite the high genetic heterogeneity of culture. As a result, the accuracy of assessing the purity of varietal material is reduced, and the breeding process is laborious and time-consuming. The widespread introduction of molecular labeling methods will make it possible to choose the most suitable breeding strategy for the development of cultivars for various purposes, adapted to certain environmental conditions.
The aim of this study was to assess the potential of the new SCoT marking technique for the identification of Russian cultivars of perennial (Lolium perenne L.) and annual (Lolium multiflorum Lam.) ryegrass.