Genome-wide assessment of population structure and genetic diversity of Chinese Lou onion using specific length amplified fragment (SLAF) sequencing

Population structure and genetic diversity of mango (Mangifera indica L.) germplasm resources as revealed by single-nucleotide polymorphism markers

Introduction

Mango is a vital horticultural fruit crop, and breeding is an essential strategy to enhance ongoing sustainability. Knowledge regarding population structure and genetic diversity in mango germplasm is essential for crop improvement.

Methods

A set of 284 mango accessions from different regions of the world were subjected to high-throughput sequencing and specific-locus amplified fragment (SLAF) library construction to generate genomic single-nucleotide polymorphism (SNP).

Results

After filtering, raw data containing 539.61 M reads were obtained. A total of 505,300 SLAFs were detected, of which, 205,299 were polymorphic. Finally, 29,136 SNPs were employed to dissect the population structure, genetic relationships, and genetic diversity. The 284 mango accessions were divided into two major groups: one group consisted mainly of mango accessions from Australia, the United States, Cuba, India, Caribbean, Israel, Pakistan, Guinea, Burma, China, and Sri Lanka, which belonged to the Indian type (P1); the other group contained mango accessions from the Philippines, Thailand, Indonesia, Vietnam, Cambodia, Malaysia, and Singapore, which belonged to Southeast Asian type (P2). Genetic diversity, principal component analysis (PCA), and population structure analyses revealed distinct accession clusters. Current results indicated that the proposed hybridization occurred widely between P1 and P2.

Discussion

Most of the accessions (80.99%) were of mixed ancestry, perhaps including multiple hybridization events and regional selection, which merits further investigation.

Deciphering genetic diversity phylogeny and assembly of Allium species through micro satellite markers on nuclear DNA

The genus Allium is the most diverse, with cultivated crops such as onion, garlic, bunching onion, chives, leeks, and shallots, and several wild and semi-domesticated Allium species utilized as minor vegetables. These minor species are the genetic resources for various abiotic and biotic stresses. To employ underutilized species in breeding programmes, the magnitude of the genetic background of cultivated and semi-domesticated alliums, the phylogeny and diversity of the population must be known. In this study, nineteen SSR markers were employed to study the divergence and population structure of 95 Allium accessions which includes species, varieties, and interspecific hybrids, yielded 92 polymorphic loci, averaging 4.84 loci per SSR. PIC values range between 0.24 (ACM 018) and 0.98 (ACM 099). The cross transferability of ACM markers among Allium species ranges from 1.33 to 10.53 per cent, which is relatively low. The genotypes investigated were clustered into four primary clusters A, B, C, and D with 13 sub clusters I-XIII, conferring to the clustering results. The population structure investigations also found that K is a peak at value 4, implying that the population is predominantly segregated into four distinct groups, which associates the clustering pattern. The employed SSR markers adeptly unravel the complexities of diversity within alliums, holding promise for refining future breeding programs targeting elite progenies.

Population Genomic Evidence for the Diversification of Bellamya aeruginosa in Different River Systems in China

Clarifying the genetic structure can facilitate the understanding of a species evolution history. It is crucial for the management of germplasm resources and providing useful guidance for effective selective breeding. Bellamya is an economically and ecologically important freshwater snail for fish, birds and even humans. Population genetic structures of the Bellamya species, however, were unknown in previous studies. Population genomics approaches with tens to hundreds of thousands of single nucleotide polymorphisms (SNPs) make it possible to detect previously unidentified structures. The population genomic study of seven populations of B. aeruginosa across three river systems (Yellow River, Yangtze River and Pearl River) in China was conducted by SLAF-seq. SLAF-seq obtained a total of 4737 polymorphisms SLAF-tags and 25,999 high-consistency genome-wide SNPs. The population genetic structure showed a clear division among populations from the Yellow River basin (YH and WL) and the Pearl River basin (QSH and LB), as well as population YC from the Yangtze River basin using the SNPs data. However, there existed no distinct population structure using the mitochondrial DNA (mtDNA). The anthropogenic translocation from the Yangtze River basin to the Pearl River basin and the passive dispersion from the Yangtze River basin to the Yellow River basin by flooding have weakened the phylogeographic pattern of B. aeruginosa. The divergence of B. aeruginosa in the three river systems suggests that the anthropogenic dispersal for aquaculture and breeding requires serious consideration of the population structure for the preservation of genetic diversity and effective utilization of germplasm resources.

Population genetics analysis of Tolai hares (Lepus tolai) in Xinjiang, China using genome-wide SNPs from SLAF-seq and mitochondrial markers

The main topic of population genetics and evolutionary biology is the influence of the ecological environment, geographical isolation, and climatic factors on population structure and history. Here, we estimated the genetic diversity, genetic structure, and population history of two subspecies of Tolai hares (Lepus tolai Pallas, 1778), L. t. lehmanni inhabiting Northern and Northwest Xinjiang and L. t. centrasiaticus inhabiting Central and Eastern Xinjiang using SNP of specific-length amplified fragment sequencing (SLAF-seq) and four mitochondrial DNA (mtDNA). Our results showed a relatively high degree of genetic diversity for Tolai hares, and the diversity of L. t. lehmanni was slightly higher than that of L. t. centrasiaticus, likely due to the more favorable ecological environment, such as woodlands and plains. Phylogenetic analysis from SNP and mtDNA indicated a rough phylogeographical distribution pattern among Tolai hares. Strong differentiation was found between the two subspecies and the two geographical groups in L. t. centrasiaticus, possibly due to the geographical isolation of mountains, basins, and deserts. However, gene flow was also detected between the two subspecies, which might be attributed to the Tianshan Corridor and the strong migration ability of hares. Tolai hare population differentiation occurred at approximately 1.2377 MYA. Population history analysis based on SNP and mtDNA showed that the Tolai hare population has a complex history and L. t. lehmanni was less affected by the glacial event, possibly because its geographic location and terrain conditions weaken the drastic climate fluctuations. In conclusion, our results indicated that the joint effect of ecological environment, geographic events, and climatic factors might play important roles in the evolutionary process of L. t. lehmanni and L. t. centrasiaticus, thus resulting in differentiation, gene exchange, and different population history.

Development of SLAF-Sequence and Multiplex SNaPshot Panels for Population Genetic Diversity Analysis and Construction of DNA Fingerprints for Sugarcane

A genetic diversity analysis and identification of plant germplasms and varieties are important and necessary for plant breeding. Deoxyribonucleotide (DNA) fingerprints based on genomic molecular markers play an important role in accurate germplasm identification. In this study, Specific-Locus Amplified Fragment Sequencing (SLAF-seq) was conducted for a sugarcane population with 103 cultivated and wild accessions. In total, 105,325 genomic single nucleotide polymorphisms (SNPs) were called successfully to analyze population components and genetic diversity. The genetic diversity of the population was complex and clustered into two major subpopulations. A principal component analysis (PCA) showed that these accessions could not be completely classified based on geographical origin. After filtration, screening, and comparison, 192 uniformly-distributed SNP loci were selected for the 32 chromosomes of sugarcane. An SNP complex genotyping detection system was established using the SNaPshot typing method and used for the precise genotyping and identification of 180 sugarcane germplasm samples. According to the stability and polymorphism of the SNPs, 32 high-quality SNP markers were obtained and successfully used to construct the first SNP fingerprinting and quick response codes (QR codes) for sugarcane. The results provide new insights for genotyping, classifying, and identifying germplasm and resources for sugarcane breeding

The Genetic Diversity of Bletilla spp. Based on SLAF-seq and Oligo-FISH

Bletilla spp. Rchb. F. is a traditional Chinese medicinal material. In this study, Bletilla striata (Thunb. ex A. Murray) Rchb F, Bletilla formosana (Hayata) Schltr, and Bletilla ochracea Schltr were collected to analyze the genetic diversity of 16 materials using specific site-amplified fragment sequencing (SLAF-seq) and fluorescence in situ hybridization (FISH). The results showed that the phylogenetic tree of the single-nucleotide polymorphism (SNP) data rendering system was correlated with the shape and geographical distribution of the material. The results of the population structural analysis showed that all the materials containing yellow labellum came from the same ancestor. The results of the principal component analysis were able to preliminarily judge the genetic distance and provided a reference for the selection of hybrid parents. The FISH analysis showed that the chromosomes of B. striata were 2n = 32 and the chromosomes of the B. striata (safflower) mutant were 2n = 34 and the chromosomes of B. ochracea and B. formosana were 2n = 34–36. The (AG₃T₃)₃ non-terminal signal was different from the 5S rDNA signal. These results revealed that the 16 materials had rich genetic diversity, which can provide molecular and cytogenetic data for the study of the genus and its relatives and serve as a reference for the breeding of new genus varieties and improve breeding efficiency and cost.