The study of inter-specific relationships of Bromus genus based on SCoT and ISSR molecular markers

Start codon targeted (SCoT) polymorphism marker in plant genome analysis: current status and prospects

The present review illustrates a comprehensive overview of the start codon targeted (SCoT) polymorphism marker and their utilization in various applications related to genetic and genomic studies. Start codon targeted (SCoT) polymorphism marker, a targeted fingerprinting marker technique, has gained considerable importance in plant genetics, genomics, and molecular breeding due to its many desirable features. SCoT marker targets the region flanking the start codon, a highly conserved region in plant genes. Therefore, it can distinguish genetic variations in a specific gene that link to a specific trait. It is a simple, novel, cost-effective, highly polymorphic, and reproducible molecular marker for which there is no need for prior sequence information. In the recent past, SCoT markers have been employed in many commercially important and underutilized plant species for a variety of applications, including genetic diversity analysis, interspecific/generic genetic relationships, cultivar/hybrid/species identification, sex determination, construction of linkage map, association mapping/analysis, differential gene expression, and genetic fidelity analysis of tissue culture-raised plants. The main aim of this review is to provide up-to-date information on SCoT markers and their application in many commercially important and underutilized plant species, mainly progress made in the last 8-10 years.

Genetic variability analysis of Russian cultivars of ryegrass (Lolium) based on SCoT markers

BACKGROUND

Ryegrass is a promising crop for the development of meadow farming in the world. More than 1000 cultivated varieties widely used in feed production have been developed, based on the main species - perennial ryegrass (Lolium perenne L.) and annual one (Lolium multiflorum Lam.). Development and implementation of the modern methods of plant varietal and species identification are of great importance. In recent years, molecular markers have been successfully used for these purposes, which increase the accuracy of the breeding material evaluation at a significant reduction of time and labor costs. The aim of this study was to assess the discriminatory potential of the new SCoT marking technique for the identification of Russian perennial (Lolium perenne L.) and annual (Lolium multiflorum Lam.) ryegrass varieties.

RESULTS

Out of the total number of the tested SCoT-primers, 8 polymorphic ones were selected, which demonstrates the high stability and reproducibly amplified DNA fragments. These primers generated 107 PCR products, where 37 were found to be polymorphic. The average number of amplicons per primer was 13. The size of the PCR products varied from 349 to 2718 bp (see Table 3). The polymorphic ratio of the tested markers was 30.8%. The marker SCoT-06 was characterized by the maximum number of PCR products and the highest level of polymorphism (50%). The effective number of alleles (ne) ranged from 1.35 to 1.58 with a mean of 1.48 per locus. The average value of the PIC and Shannon index (I) were 0.35 and 0.46, respectively. The unique PCR fragments were revealed for the identification of tested varieties. Analysis of molecular variance (AMOVA) showed that the level of genetic diversity between ryegrass species (59%) was more than between varieties within a species (41%). Based on binary matrix data, clustering and PCoA analysis (see Figs. 1 and 2) of the samples were carried out that divided them into two groups according to species.

CONCLUSIONS

We found a set of markers that can be useful tools for ryegrass varieties identification. The level of intravarietal polymorphism turned out to be higher than the differences between varieties because of the possible significant heterogeneity of the varietal material. The information obtained can be used in breeding programs to create improved ryegrass varieties adapted to Russian climatic conditions.

The complete chloroplast genome of Bromus biebersteinii

Bromus biebersteinii is a perennial gramineous grass, which is mainly distributed in Southwest Asia. In our study, we obtained the complete chloroplast genome of B. biebersteinii and found it is 137,189 bp in length. The GC content of its whole chloroplast genome is 38.37%. Among the 134 unique genes in the circular genome, 38 tRNA, 8 rRNA and 88 protein-coding genes were successfully annotated. We constructed the Maximum likelihood (ML) tree with 12 species, and found that B. biebersteinii was phylogenetically close to Bromus vulgaris of the genus Bromus.

A comparative assessment of morphological and molecular characterization among three Ziziphus species

Genetic variability of 84 accessions of three Ziziphus species including Z. spina-christi, Z. nummularia and Z. mauritiana were analyzed using a combination of morphological traits and translation initiation codon (ATG) polymorphism. Both morphological and molecular data revealed a high level of inter and intra specific variations among the accessions. Accordingly, 90.49% of amplified fragments were polymorphic among the accessions with the mean values of 0.37 for polymorphic information content (PIC), 3.31 for resolving power (RP), and 1.95 for marker index (MI). The phylogenetic clustering clearly delineated the entire germplasm into three well supported distinct clusters according to the species sources. According to the Nei's genetic identity, Z. spina-christi and Z. nummularia were the most similar species and had high differentiation with Z. mauritiana. Moreover, the highest values for Shannon's information index (I = 0.505) and gene diversity (h = 0.347) were recorded in Z. spina-christi indicating there is higher genetic diversity compared with two other species. Four private alleles were identified in two species which could be beneficial for accessions authentication in argumentative situations. Moreover, results of the Mantel test showed there were moderate correlation between molecular and morphological matrices. In addition, estimation of bivariate correlations revealed there were significant positive and negative correlations between different variables, which offer a practical application of this information during phenotype based selection in ber improvement programs. The results of this investigation highlight the efficiency of translation initiation codon polymorphism for genetic characterization and accurate authentication of Ziziphus accessions as well as detecting and tagging morphologically important traits in this genus that would be helpful for implementation of effective conservation strategies and even broaden current genetic diversity.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s12298-021-01000-7.

DNA Fingerprinting and Genetic Relationships Similarities Among the Accessions/Species of Ocimum Using SCoT and ISSR Markers System

Studies on genetic diversity could enhance taxonomic authentication and evolutionary relationship among the species of Ocimum. Therefore, diversity among 36 Ocimum accessions representing species from different regions of world were analyzed using Start Codon-Targeted Polymorphism (SCoT) and inter-simple sequences repeat (ISSR) marker. Marker systems used in this study was potentially targeted the different regions of the genome and included 18 SCoT and 15 ISSR primers, which showed successful amplification profile for Ocimum. Between these two, SCoT revealed the highest mean value of percentage of Polymorphism (84.6%), polymorphic information content (PIC, 0.65), and resolving power (Rp, 8.80), which were higher than ISSR. A total of 140 and 111 amplicons were obtained with SCoT and ISSR marker. The Mantel test indicted a significant correlation (r² = 0.44) between ISSR and SCoT, which suggested a common genetical background among the accessions. The principal coordinate study showed the selection of different Ocimum genotypes by the cluster analysis. This study will help and support identification, genetic mapping, and molecular ecology to enhance the breeding program's efficiency for developing elite varieties to meet industrial demand globally. The present study is the first report of the genetic diversity, and relationship determination with SCoT-based molecular marker among Ocimum accessions.