Development of Kompetitive Allele Specific PCR markers for identification of persimmon varieties using genotyping-by-sequencing

Low-density SNP marker sets for genetic variation analysis and variety identification in cultivated citrus

BACKGROUND

The Citrus species are major fruit crops cultivated in the world and have complex genetic relationships due to sexual comparability between Citrus and related genera. Of these, satsuma mandarin (C. unshiu (Mak.) Marc.) and sweet orange (C. sinensis (L.) Osb.) are widely grown diploid species. In this study, genotyping by sequencing (GBS) was conducted to identify single nucleotide polymorphisms (SNPs) for investigating genetic variation in a citrus collection.

RESULTS

A total of 26,903 high-quality SNPs were detected across nine chromosomes in the 144 citrus varieties, consisting of 70 C. unshiu, 40 C. sinensis, 22 interspecific hybrids, and 12 others. Of these, a core set of 481 SNPs was filtered based on polymorphism information content and genome distribution. Both principal component analysis (PCA) and model-based clustering showed genetic differentiation between C. unshiu and C. sinensis. For interspecific hybrids, these were separated from two species in PCA, but were mixed with each species in model-based clustering. Significant genetic differentiations between three populations were also found using the pairwise Fst. In addition, interspecific hybrids showed higher level of genetic diversity relative to the C. unshiu and C. sinensis populations. With the 481 SNPs, four subsets (192, 96, 48, and 24 SNPs) were generated to evaluate their performance for variety identification. Both 192 and 96 SNP sets distinguished all 144 varieties, while the 48 and 24 SNP sets separated 134 (93.1%) and 110 (76.4%), respectively.

CONCLUSIONS

The GBS-based SNP discovery led to robust and cost-effective molecular marker sets to assess genetic variation in the cultivated citrus species with narrow genetic bases. The resulting SNP sets are a resource to enhance the phenotype-based DUS testing by developing a DNA barcode system and thus facilitate new variety breeding and protection in citrus.

Assessment of phylogenetic relationships and genetic diversity of Sagittaria trifolia using phenotypic traits and SNP markers

The aquatic perennial herb Sagittaria trifolia L. commonly known as arrowhead, has been utilized in China both as a culinary vegetable and in traditional medicines. Characterizing the phylogenetic relationships and genetic diversity of arrowheads is crucial for improved management, conservation, and efficient utilization of the germplasm resources associated with this species. Herein, we presented the phenotypic traits and genome-wide DNA marker-based analyses of 111 arrowhead accessions, most of which were from China. Cluster analysis revealed that arrowhead could be categorized into two clusters based on 11 phenotypic traits, with Cluster 1 comprising two subclusters. All accessions were clustered into three sub-clusters based primarily on leaf shape and tuber weight. A set of 759,237 high-quality single-nucleotide polymorphisms was identified and used to assess the phylogenetic relationships. Population structure and phylogenetic tree analyses suggested that the accessions could be classified into two major groups, Group I was further subdivided into two subgroups, aligning with the clusters identified through morphological classification. By employing Sagittaria lichuanensis as an outgroup, the rooted tree revealed that the evolutionary relationships within the three groups followed a progression from Group I-1 to Group I-2 and finally to Group II. The landraces were clustered into one group along with the remaining wild accessions. The level of genetic diversity for Group I (π = 0.26) was slightly lower than that which was estimated for Group II (π = 0.29). The lowest pairwise differentiation levels (Fst, 0.008) were obtained from the comparison between groups I-2 and II, indicating that the two groups were the most closely related. This study provides novel insights into germplasm classification, evolutionary relationships, genomics and arrowhead breeding.

Population Genetic Analysis in Persimmons (Diospyros kaki Thunb.) Based on Genome-Wide Single-Nucleotide Polymorphisms

This study investigated the genetic diversity and population structure of a persimmon (Diospyros kaki Thunb., 2n = 6x = 90) collection in South Korea by evaluating 9751 genome-wide single-nucleotide polymorphisms (SNPs) detected using genotyping-by-sequencing in 93 cultivars. The results of neighbor-joining clustering, principal component analysis, and STRUCTURE analysis based on SNPs indicated clear separation between cultivar groups (pollination-constant nonastringent (PCNA, 40 cultivars), pollination-constant astringent (PCA, 19), pollination-variant nonastringent (PVNA, 23), and the pollination-variant astringent type (PVA, 9)) based on the astringency types, while separation between PVA and PVNA-type cultivars was unclear. Population genetic diversity based on SNPs showed that the proportions of polymorphic SNPs within each group ranged from 99.01% (PVNA) to 94.08% (PVA), and the PVNA group exhibited the highest genetic diversity (He = 3.86 and uHe = 0.397). F (fixation index) values were low ranging from -0.024 (PVA) to 0.176 (PCA) with an average of 0.089, indicating a deficiency of heterozygosity. Analysis of molecular variance (AMOVA) and Fst among cultivar groups indicated that variation within individuals was higher than that among the groups. Pairwise Fst values among the groups ranged from 0.01566 (between PVA and PVNA) to 0.09416 (between PCA and PCNA), indicating a low level of cultivar type differentiation. These findings highlight the potential application of biallelic SNPs in population genetics studies of allopolyploids species and provide valuable insights that may have significant implications for breeding and cultivar identification in persimmon.

Discrimination of Panax ginseng from counterfeits using single nucleotide polymorphism: A focused review

Discrimination of plant species, cultivars, and landraces is challenging because plants have high phenotypic and genotypic resemblance. Panax ginseng is commonly referred to as Korean ginseng, which contains saponins with high efficacy on cells, and has been reported to be worth billions in agroeconomic value. Korean ginseng's increasing global agroeconomic value includes additional species and cultivars that are not Korean ginseng but have physical characteristics close to it. This almost unidentifiable physical characteristic of Korean ginseng-like species is discriminated via molecular markers. Single nucleotide polymorphism (SNP), found across the plant species in abundance, is a valuable tool in the molecular mapping of genes and distinguishing a plant species from adulterants. Differentiating the composition of genes in species is quite evident, but the varieties and landraces have fewer differences in addition to single nucleotide mismatch. Especially in the exon region, there exist both favorable and adverse effects on species. With the aforementioned ideas in discriminating ginseng based on molecular markers, SNP has proven reliable and convenient, with advanced markers available. This article provides the simplest cost-effective guidelines for experiments in a traditional laboratory setting to get hands-on SNP marker analysis. Hence, the current review provides detailed up-to-date information about the discrimination of Panax ginseng exclusively based on SNP adding with a straightforward method explained which can be followed to perform the analysis.

Application of Allele Specific PCR in Identifying Offspring Genotypes of Bi-Allelic SbeIIb Mutant Lines in Rice

Bi-allelic mutant lines induced by clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR associated (Cas) systems are important genetic materials. It is very important to establish a rapid and cheap method in identifying homozygous mutant plants from offspring segregation populations of bi-allelic mutant lines. In this study, the offspring genotypes of rice bi-allelic starch branching enzyme IIb mutant lines were identified using the allele specific PCR (AS-PCR) method. The target sequences of two alleles were aligned from their 5′ to 3′ ends, and the first different bases were used as the 3′ ends of mismatch primers. Another mismatched base was introduced at the third nucleotide from the 3′ end of mismatch primer. The PCR reaction mixture and amplification program were optimized according to the differences of mutation target sequence and mismatch primers. The offspring plant genotypes of bi-allelic mutant lines could be accurately identified using the amplified DNA fragments by agarose gel electrophoresis. This study could provide a method reference for the rapid screening of homozygous mutant plants from offspring segregation population of heterozygous and bi-allelic mutant lines.

Transcriptome analysis and genetic diversity of Allium victorialis germplasms from the Changbai Mountains

The Changbai Mountains comprise one of the main distribution areas of A. victorialis in China, and this species is endangered owing to habitat changes and overexploitation. However, A. victorialis germplasms have not been systematically collected and studied. The aims of this study were to obtain some detailed genetic information, analyze the genetic diversity, and further promote the protection of A. victorialis germplasms from the Changbai Mountains. Transcriptomic analysis was performed with six A. victorialis samples collected from the Changbai Mountains. At least 146,759 genes for each sample were obtained after performing de novo assembly of the RNA-seq data, and at least 92% of these genes were found to have only one mRNA isoform. These sequences and their functional annotations provided a large-scale genetic resource of this species. Phylogenetic analysis showed that A. victorialis was genetically distant from some related species, e.g. Allium sativum, Allium fistulosum, and Allium cepa, but genetically close to Allium tuberosum. The two A. victorialis var. listera samples were phylogenetically separated from the other four samples, and these two samples should be regarded as Allium listera. In addition, two KASP markers for discriminating the Dongfeng samples from the other four A. victorialis samples were successfully developed. This study lays the foundation for future studies on the genetic diversity and evolution of Allium species, as well as for the conservation of A. victorialis germplasms from the Changbai Mountains and other populations of this species.

Genetic Diversity in Diospyros Germplasm in the Western Caucasus Based on SSR and ISSR Polymorphism

Simple Summary

Persimmon is an edible fruit consisting of several species in the genus Diospyros. The most widely cultivated and most commercially important species is the Oriental persimmon, Diospyros kaki. However, the inter- and intra-specific genetic diversity of the genus Diospyros remains largely unclear and is of great interest both for conservation and breeding purposes. This study describes the genetic diversity and genetic admixture of Diospyros germplasm in the Western Caucasus. The information can be used to support conservation measures and the breeding of persimmon.

Abstract

Persimmon germplasm in the Western Caucasus represent one of the most northerly collections. In our study, 51 commercial cultivars of D. kaki, 3 accessions of D. virginiana and 57 D. lotus accessions from six geographically distant populations were investigated using 19 microsatellite and 10 inter simple sequence repeat (ISSR) markers. After STRUCTURE analysis, the single accessions of Diospyros were allocated to three genetic clusters. Genetic admixtures in the important genotypes of D. kaki were revealed, whereas D. lotus accessions showed no admixture with other genetic clusters. The correspondence of genetic data and phenotypical traits was estimated in the D. kaki collection. The most frost tolerant genotypes of the collection, such as “Mountain Rogers”, “Nikitskaya Bordovaya”, “Rossiyanka”, “MVG Omarova”, “Meader”, “Costata”, “BBG”, and “Jiro”, showed a high percentage of genetic admixtures and were grouped close to D. virginiana. Some of these genotypes are known to be interspecific hybrids with D. virginiana. A low level of genetic diversity between the distant D. lotus populations was revealed and it can be speculated that D. lotus was introduced to the Western Caucasus from a single germplasm source. These results are an important basis for the implementation of conservation measures, developing breeding strategies, and improving breeding efficiency.