Genome Resequencing Research Articles

Four new genome sequences of the Pallas’s cat (Otocolobus manul): an insight into the patterns of within-species variability

Manul (Otocolobus manul) is the only representative of the genus Otocolobus, which makes up the Leopard Cat lineage along with the genus Prionailurus. Their habitat is characterized by harsh environmental conditions. Although their populations are probably more stable than previously thought, it is still the case that their population size is declining. Conservation programs exist to protect manuls, but those based on captive breeding are often unsuccessful due to their increased susceptibility to diseases. The manul is therefore a suitable model species for evolutionary and diversity studies as well as for studying mechanisms of adaptation to harsh environment and mechanisms of susceptibility to diseases. Recently, the genome of the O. manul based on nanopore long-range sequencing has been published. Aiming to better understand inter- and intraspecific variation of the species, we obtained information on genome sequences of four other manuls, based on whole genome resequencing via the Illumina platform. On average, we detected a total of 3,636,571 polymorphic variants. Information on different types of structural variants and on the extent of SNP homozygosity, not available from the reference genome, was retrieved. The average whole-genome heterozygosity was almost identical to that found in the O. manul reference genome. In this context, we performed a more detailed analysis of the candidate gene EPAS1 potentially related to adaptation to the hypoxic environment. This analysis revealed both inter- and intraspecific variation, confirmed the presence of a previously described non-synonymous substitution in exon 15 unique to manuls and identified three additional unique non-synonymous substitutions located in so far not analyzed EPAS1 exonic sequences. The analysis of lncRNA located in the intron 7 of EPAS1 revealed interspecific variability and monomorphic nature of the sequence among analyzed manuls. The data obtained will allow more detailed analyses of the manul genome, focusing on genes and pathways involved in their adaptation to the environment and in susceptibility to diseases. This information can be helpful for optimizing conservation programs for this understudied species.

Thwarting the Blight: A Comprehensive Review of Traditional and Molecular Germplasm Screening Techniques for Black Spot Resistance in Roses

Diplocarpon rosae causing rose black spot disease, is one of the most devastating pathogens, that affect the quality of roses, and is responsible for huge yield losses, worldwide. Many approaches have been applied to control this disease including developing resistance variety. However, this review widely evaluates different screening germplasm methods to control the black-spot disease in rose. Additionally, in this review, many major issues influencing the black-spot disease resistance, including environmental factors, plant-pathogen interaction and genetic diversity, providing a complete thoughtful of the multifaceted nature of this disease. Moreover, the variety of screening technique ranging from conventional field assessment to contemporary molecular approaches, emphasizing their respective benefits and restrictions. But, the finding and employing new resistance genes is very difficult due to highly genetic diversity of this pathogen, especially, when their interaction of this pathogen to plant are not completely understood. Because, various isolates and strains of pathogen can relate in diverse ways with different germplasm, making it challenging to identify uniform resistance among all strains. Furthermore, many environmental factors including light, temperature and humidity support to increase the disease development, leading reduce the resistance and tolerance of plant against pathogen. Whereas, developing resistance germplasm might be helpful to control this disease and reduce pathogen infection in plants. In this regard, many plant-omics studies such as transcriptome, genome re-sequencing and proteomics have been widely studied to find out candidate resistance (R) protein and genes, which related to the black-spot disease. This review seeks to provide researchers as well as growers and breeders with a through recourse that combine recent information on the assessment of rose germplasm against black spot disease resistance. By employing newly approaches, we aimed to accelerate the growth of rose varieties, that are beautifully attractive and strong in the appearance on this determined blight. In the last, our collective finding to addresses the issues could be increase the sustainability and visual attractiveness of rose cultivation for future generations.

Genome-wide association analysis of eggshell pore traits based on whole genome resequencing

Eggshell pores can be subdivided into micrometer-scale gas pores, submicroscopic bubble pores, and nanoscale mesopores. All are important indicators of eggshell quality ensuring gas exchange between the inside and outside of the eggshell and preventing invasion by external bacteria. Although previous studies on eggshell pores focused on gas pores, recent studies have shown that bubble pores may play an more important role in regulating gas exchange. In order to investigated the relationship between gas and bubble pores and the mechanisms of genetic regulation. In this study, 40-week-old Brown-Egg Dwarf Layers (DWL) eggs were selected, and the quantity of gas pores (QGP), quantity of mammillary (QM), and quantity of bubble pores (QBP), area sum of bubble pores (ASBP), and other bubble pore-related indexes were determined. The correlation between each index was calculated, and genome-wide association analysis (GWAS) was performed based on whole genome resequencing (WGR). The results showed that the CVs of QGP and QM were 15.69% and 15.49%, respectively, and the CVs of the related pore indices, such as QBP and ASBP, were 29.22%-44.82%. The correlation coefficient between QGP and QM was 0.59 (P< 0.01), and there was no correlation between QGP, QM, and the bubble pore-related indicators (P > 0.05). These results above suggest that the gas and bubble pores may be two independent pore systems. A total of 32 single nucleotide polymorphisms (SNPs) associated with the suggestively significant level of bubble pore correlation indexes were detected in GWAS, and the corresponding genes were ANXA10, CDH10, AADAT, RXFP1, FNIP2, DDX60, PCDH10, RAPGEF2, FSTL5 and SPOCK3. KEGG enrichment analysis showed that these genes were mainly expressed in the calcium ion binding pathway, indicating that the genes and pathways may play a regulatory role in forming bubble pores during eggshell calcification. This study provides a basis for revealing the genetic regulatory mechanism of eggshell pores and a reference and direction for further improvement in eggshell quality.

Genome-wide association and transcriptomic analysis and the identification of growth-related genes in Macrobrachium nipponense

Macrobrachium nipponense is a commercially important freshwater species of prawn that is widely distributed across Asian countries. In order to investigate the molecular mechanisms of growth in M. nipponense, and to provide a foundation for molecular breeding, we used genome-wide association analysis (GWAS) and transcriptomic analysis to screen polymorphisms and genes related to growth traits. We recorded the growth traits of 100 adult M. nipponense at the same growth stage, and each individual genotype was evaluated by whole genome resequencing. GWAS of growth traits detected 12 growth-related single-nucleotide polymorphisms (SNPs) and eight growth-related genes from 49 chromosomes. Of the 100 individuals, we sampled muscle tissue from a total of 18 female and male M. nipponense exhibiting large differences in growth rate for RNA-seq. Transcriptome analysis revealed a total of 27,996 unigenes; of these, 33 and 60 differentially expressed genes were identified from males and females, respectively. Of these, 12 genes associated with energy metabolism and cytoskeletal pathways were identified as growth-related genes. Notably, genes from the actin family and the ubiquitin C-terminal hydrolase 2 (UCH2) gene were identified by both GWAS and transcriptomic analysis. Two growth-related SNPs, S40_12327385 and S40_12327391, were found to be mapped to the ACTB gene. The ACTA1 gene, also from the actin family, was up-regulated in fast-growing males and females, while the ACT57B was down-regulated. In addition, the growth associated SNP S7_35313774 was located in the UCH2 gene; transcriptomics analysis revealed that the UCH2 gene was up-regulated in female individuals exhibiting high growth rates. Overall, our results provided a set of markers and candidate genes related to the growth of M. nipponense. These findings could facilitate the breeding management of this species and help us to further understand the genetic mechanisms of growth in crustaceans.

Dissection of major QTLs and candidate genes for seedling stage salt/drought tolerance in tomato

BackgroundAs two of the most impactful abiotic stresses, salt and drought strongly affect tomato growth and development, especially at the seedling stage. However, dissection of the genetic basis underlying salt/drought tolerance at seedling stage in tomato remains limited in scope.ResultsHere, we reported an analysis of major quantitative trait locus (QTL) and potential causal genetic variations in seedling stage salt/drought tolerance in recombinant inbred lines (n = 201) of S. pimpinellifolium and S. lycopersicum parents by whole genome resequencing. A total of 5 QTLs on chromosome 1, 3, 5, 7 and 12 for salt tolerance (ST) and 15 QTLs on chromosome 1, 3, 4, 8, 9, 10, 12 for drought tolerance (DT) were identified by linkage mapping. The proportion of phenotypic variation explained (PVE%) by these QTLs ranged from 4.91 to 15.86. Two major QTLs qST7 and qDT1-3 were detected in both two years, for which two candidate genes (methionine sulfoxide reductase SlMSRB1 and brassinosteroid insensitive 1-like receptor SlBRL1) and the potential functional variations were further analyzed. Taking advantage of the tomato population resequencing data, the frequency changes of the potential favorable QTL allele for seedling stage ST/DT during tomato breeding were explored.ConclusionsThese results will be beneficial for the exploration of salt/drought tolerance genes at seedling stages, laying a foundation for marker-assisted breeding for seedling stage salt/drought tolerance.

Extensive cytonuclear discordance revealed by phylogenomic analyses suggests complex evolutionary history in the holly genus Ilex (Aquifoliaceae)

Ilex L., the exclusive genus of Aquifoliaceae, encompasses over 600 dioecious wood species with a highly irregular distribution, predominantly found in South America and Asia. The phylogeny and classification of this genus remain enigmatic due to significant early extinctions, constrained morphological diversity, recent hybridization/introgression, and conflicting signals from previously utilized markers. This study presents phylogenetic reconstructions based on complete chloroplast genome sequences and single nucleotide polymorphisms (SNPs) derived from genome resequencing data. A total of 116 accessions of Ilex, representing approximately 108 taxa, were included as the ingroup, with five accessions of two species serving as outgroups. Analysis of the chloroplast genome and nuclear SNP data individually resulted in two robust phylogenetic trees, revealing substantial discrepancies between the chloroplast genome and nuclear SNP phylogenies at both the species and clade levels. The chloroplast genome sequences successfully resolved relationships within this genus into eight strongly supported major clades, while the nuclear SNPs resolved relationships into seven highly supported major clades. Our nuclear SNP phylogenetic tree, in comparison to the chloroplast genome tree, aligns more closely with the recently updated classification of Ilex in multiple instances. The extensive cytonuclear discordance identified may be attributed to recent hybridization events and incomplete lineage sorting (ILS).

A chromosome-level reference genome for the common bed bug, Cimex lectularius, with identification of sex chromosomes.

The common bed bug, Cimex lectularius, is a globally distributed pest insect of medical, veterinary, and economic importance. Previous reference genome assemblies for this species were generated from short read sequencing data, resulting in a ~650Mb composed of thousands of contigs. Here, we present a haplotype-resolved, chromosome-level reference genome, generated from an adult Harlen strain female specimen. Using PacBio long read and Omni-C proximity sequencing, we generated a 540Mb genome with 15 chromosomes (13 autosomes and 2 sex chromosomes - X1X2) with an N50 > 30Mb and BUSCO > 90%. Previous karyotyping efforts indicate an XY sex chromosome system, with 2n=26 and X1X1X2X2 females and X1X2Y males; however significant fragmentation of the X chromosome has also been reported. We further use whole genome resequencing data from males and females to identify the X1 and X2 chromosomes based on sex biases in coverage. This highly contiguous reference genome assembly provides a much-improved resource for identifying chromosomal genome architecture, and for interpreting patterns of urban outbreaks and signatures of selection linked to insecticide resistance.

Adaptive evolution and mechanism elucidation for ethanol tolerant Saccharomyces cerevisiae used in starch based biorefinery

Ethanol tolerant Saccharomyces cerevisiae is compulsory for ethanol production in starch based biorefinery, especially during high-gravity fermentation. In this study, adaptive evolution with increased initial ethanol concentrations as a driving force was harnessed for achieving ethanol tolerant S. cerevisiae. After evolution, an outstanding ethanol tolerant strain was screened, which contributed to significant improvements in glucose consumption and ethanol production in scenarios of 300 g/L initial glucose, high solid loadings (30 wt%, 33 wt%, 35 wt% and 40 wt%) of corn, and high solid loadings (30 wt% and 33 wt%) of cassava, compared with the original strain. Genome re-sequencing was applied for the evolved strain, and 504 sense mutations in 205 genes were detected, among which PAM1 gene was demonstrated related to the elevated ethanol tolerance. In sum, this study provided a practical approach for obtaining ethanol tolerant strain and the identified PAM1 gene enhanced our understanding on ethanol tolerant mechanism, as well as provided a target basis for rational metabolic engineering.

Preliminary exploration of the mechanisms underlying morphology engineering of Monascus purpureus during submerged fermentation via multi-omics approaches

Herein, multi-omics approaches were employed to investigate the relationship between mycelia morphology and biosynthesis of Monascus pigments (MPs) during submerged fermentation of Monascus purpureus. Through heavy ion beam irradiation, eleven mutants with diverse mycelial morphologies and MPs productions were generated. Genome resequencing analysis revealed that the autologous genes of these mutants were primarily enriched in pathways associated with histone ubiquitination and methylation. Among them, M. purpureus ZS exhibited a 2.49-fold increase in MPs production and distinct mycelia morphology compared to the parent strain, thus it was selected for transcriptomic and metabolomic analyses. The results revealed showed significant alterations in lysine metabolism, lipid metabolism, as well as cell wall and membrane components. Additionally, upregulated CoA biosynthesis along with type I polyketide structures and the genetic cluster responsible for MPs biosynthesis facilitated accumulation of MPs. These findings provide a theoretical foundation for morphological engineering of Monascus while offering novel strategies to achieve higher levels of MPs production during submerged fermentation.

A draft genome assembly and resequencing analysis of Chinese cherry (Cerasus pseudocerasus) reveal structural variants associated with fruit traits

A draft genome assembly and resequencing analysis of Chinese cherry (Cerasus pseudocerasus) reveal structural variants associated with fruit traits

Investigation of genetic diversity in the loach Misgurnus anguillicaudatus revealed by whole-genome resequencing

BackgroundThe loach (Misgurnus anguillicaudatus) is a significant freshwater economic fish in China, renowned for its tender meat, delicious taste, and high nutritional value. It is widely distributed across the country, except for the western plateau. However, the loach is currently at risk of population decline and degradation of wildlife resources. Research on genetic diversity provides a crucial foundation for the conservation and development of these fish resources. To enhance the protection and utilization of wild loach germplasm resources, we analyzed the genetic structure and diversity of 60 wild loach populations from Xiangtan City (XT), Shaoyang City (SY), and Yueyang City (XY) in Hunan, Guilin City (GL) and Guiping City (GP) in Guangxi, and Wuhan City (WH) in Hubei. Additionally, we mapped the DNA fingerprints of these 60 wild loaches using 12 high-quality SNP sites.ResultsWhole genome resequencing (WGRS) was conducted on 60 loaches from six regions, yielding a total of 1047.17 Gb of raw data and 1046.98 Gb of clean data. From this 2,812,906 high-quality single nucleotide polymorphisms (SNPs) were identified, of which 10,022 core SNPs were selected to analyze the population genetic structure, and 12 core SNPs were used to assess the genetic diversity and DNA fingerprint. The analysis revealed that the 60 loach samples could be grouped into three clusters: Cluster A comprised the XT, SY, and XY groups; Cluster B included the WH group; and Cluster C consisted of the GL and GP groups. The mean nucleic acid diversity (Pi), heterozygosity (Ho), and expected heterozygosity (He) of SNP markers were 0.130, 0.140, and 0.123, respectively. The average inbreeding coefficient was 0.552, indicating high levels of inbreeding.ConclusionsWhole genome resequencing is an effective high-throughput approach for identifying SNP information in loach germplasm and describing genetic relationships within this genus. DNA fingerprinting based on SNP marker technology can accurately assess the genetic structure and variation within natural loach populations, making it a valuable tool for strain and variation identification. Our findings provide a scientific basis for the conservation, development, and optimal breeding of native loach germplasm resources and contribute to expanding the genetic diversity database of wild loach populations.

Cold Plasma Treatment Facilitated the Conversion of Lignin-Derived Aldehyde for Pseudomonas putida.

Syringaldehyde derived from lignin is one of the essential intermediates for the production of basic chemicals. However, it was poorly understood for the direct microbial conversion of syringaldehyde. Here, this study tried to use cold plasma technique to enhance syringaldehyde conversion for the bacterium Pseudomonas putida. It illustrated that cell growth and syringaldehyde conversion were separately increased by 1.49 times at 3 h and 1.60 times at 6 h for 35 s, 1.16 and 3.44 times for 140 W, and 1.63 and 4.02 times for 105 Pa for P. putida through single factor assays of cold plasma treatment. To be sure, cell growth and syringaldehyde conversion were enhanced by 1.14 and 5.54 times at 3 h under the optimum parameters (35s, 140 W, and 105Pa) for P. putida. Furthermore, genome re-sequencing further discovered single-nucleotide polymorphisms of P. putida, such as PP_2589 (A428V), PP_5651 (V82F), and PP_0545 (W335R), and thus indicated that the potential genetic changes derived from cold plasma treatment would be responsible for the acceleration of syringaldehyde conversion. This work would provide a robust strain catalyst and the potential candidate mutation sites for genetic manipulation for microbial bioconversion of the value-added and lignin-based biochemicals.

Characterization of the sex determining region and development of a molecular sex identification method in a Salangid fish

BackgroundThe short-snout icefish, Neosalanx brevirostris, a member of the Salangidae family, is an economically important fishery species in China. Understanding the mechanisms underlying sex determination in this species has crucial implications for conservation, ecology and evolution. Meanwhile, there is a shortage of rapid and cost-effective genetic methods for sex identification, which poses challenges in identifying the sex of immature individuals in sex determination mechanism studies and aquaculture breeding applications.ResultsBased on whole genome resequencing data, sex-specific loci and regions were found to be concentrated in a region on chromosome 2. All sex-specific loci exhibited excess heterozygosity in females and complete homozygosity in males. This sex determining region contains seven genes, including cytochrome P450 aromatase CYP19B, which is involved in steroidogenesis and is associated with 24 sex-specific loci and two W-deletions. A haploid female-specific sequence was identified as paralogous to a diploid sequence with a significant length difference, making it suitable for rapid and cost-effective genetic sex identification by traditional PCR and agarose gel electrophoresis, which were further validated in 24 females and 24 males with known phenotypic sexes.ConclusionsOur results confirm that N.brevirostris exhibits a female heterogametic sex determination system (ZZ/ZW), with chromosome 2 identified as the putative sex chromosome containing a relatively small sex determining region (~ 48 Kb). The gene CYP19B is proposed as a candidate sex determining gene. Moreover, the development of PCR based method enables genetic sex identification at any developmental stage, thereby facilitating further studies on sex determination mechanisms and advancing aquaculture breeding applications for this species.

Synthetic communities derived from the core endophytic microbiome of hyperaccumulators and their role in cadmium phytoremediation

BackgroundAlthough numerous endophytic bacteria have been isolated and characterized from cadmium (Cd) hyperaccumulators, the contribution and potential application of the core endophytic microbiomes on facilitating phytoremediation were still lack of intensive recognition. Therefore, a 2-year field sampling in different location were firstly conducted to identify the unique core microbiome in Cd hyperaccumulators, among which the representative cultivable bacteria of different genera were then selected to construct synthetic communities (SynComs). Finally, the effects and mechanisms of the optimized SynCom in regulating Cd accumulation in different ecotypes of Sedum alfredii were studied to declare the potential application of the bacterial agents based on core microbiome.ResultsThrough an innovative network analysis workflow, 97 core bacterial taxa unique to hyperaccumulator Sedum was identified based on a 2-year field 16S rRNA sequencing data. A SynCom comprising 13 selected strains belonging to 6 different genera was then constructed. Under the combined selection pressure of the plant and Cd contamination, Alcaligenes sp. exhibited antagonistic relationships with other genera and plant Cd concentration. Five representative strains of the other five genera were further conducted genome resequencing and developed six SynComs, whose effects on Cd phytoremediation were compared with single strains by hydroponic experiments. The results showed that SynCom-NS comprising four strains (including Leifsonia shinshuensis, Novosphingobium lindaniclasticum, Ochrobactrum anthropi, and Pseudomonas izuensis) had the greatest potential to enhance Cd phytoremediation. After inoculation with SynCom-NS, genes related to Cd transport, antioxidative defense, and phytohormone signaling pathways were significantly upregulated in both ecotypes of S. alfredii, so as to promote plant growth, Cd uptake, and translocation.ConclusionIn this study, we designed an innovative network analysis workflow to identify the core endophytic microbiome in hyperaccumulator. Based on the cultivable core bacteria, an optimized SynCom-NS was constructed and verified to have great potential in enhancing phytoremediation. This work not only provided a framework for identifying core microbiomes associated with specific features but also paved the way for the construction of functional synthetic communities derived from core microbiomes to develop high efficient agricultural agents.5KavnCJpVp3k2g6uQCMsTeVideo

Parental Reconstruction from a Half-Sib Population of Stoneless Jujube Ziziphus jujuba Mill. Based on Individual Specific SNP Markers Using Multiplex PCR.

The selection of unique and individual-specific SNPs is important as compared with universal SNPs for individual identification. Therefore, the main significance of this research is the selection of specific SNPs in male parent and the identification of offspring with these specific SNPs in their genome by multiplex PCR, which is utilized for genotyping of 332 half-sib plants of Ziziphus jujuba.This cost-effective method makes as much as possible to utilize the same amount of each pair of various targeted loci primers. After PCR amplification of targeted genome parts, the mixed products can be directly used in a next-generation sequencing platform. We concomitantly amplified 10 unique SNP loci at 10 different chromosomes of male JingZao 39 plants in 332 half-sib plants and sequenced them on the Illumina Novaseq 6000 platform. Analysis of SNP genotyping accuracy of 332 half-sib plants showed that all 10 unique SNPs in all 332 plants were correctly amplified in this multiplex PCR method. Furthermore, based on Mendelian inheritance, we identified 124 full-sib plants that have 10 unique SNPs in their genomes. These results were further confirmed by whole genome resequencing of 82 randomly selected half-sib plants, and the identity-by-descent values of all full-sib plants were between 0.4399 to 0.5652. This study displayed a cost-effective multiplex PCR method and proper identification of pollen parent through specific SNPs in half-sib progenies and firstly obtained a full-sib population between 'Wuhezao' and 'JingZao 39', segregating for stone and stoneless fruit.

Genomic Comparisons Revealed the Key Genotypes of Streptomyces sp. CB03234-GS26 to Optimize Its Growth and Relevant Production of Tiancimycins.

Strain robustness and titer improvement are major challenges faced in the industrial development of natural products from Streptomyces. Tiancimycins (TNMs) produced by Streptomyces sp. CB03234 are promising anticancer payloads for antibody-drug conjugates, but further development is severely limited by the low titer of TNMs. Despite many efforts to generate various TNMs overproducers, the mechanisms underlying high TNMs production remain to be explored. Herein, genome resequencing and genomic comparisons of different TNMs overproducers were conducted to explore the unique genotypes in CB03234-GS26. Four target genes were selected for further bioinformatic analyses and genetic validations. The results indicated that the inactivation of histidine ammonia-lyase (HAL) showed the most significant effect by blocking the intracellular degradation of histidine to facilitate relevant enzymatic catalysis and thus improve the production of TNMs. Additionally, the potassium/proton antiporter (P/PA) was crucial for intracellular pH homeostasis, and its deficiency severely impaired the alkaline tolerance of the cells. Subsequent pan-genomic analysis suggested that HAL and P/PA are core enzymes that are highly conserved in Streptomyces. Therefore, HAL and P/PA represented novel targets to regulate secondary metabolism and enhance strain robustness and could become potential synthetic biological modules to facilitate development of natural products and strain improvement in Streptomyces.

Genetic Variation Study of Several Romanian Pepper (Capsicum annuum L.) Varieties Revealed by Molecular Markers and Whole Genome Resequencing.

Numerous varieties of Capsicum annuum L. with multiple valuable traits, such as adaptation to biotic and abiotic stress factors, can be found in south-east Romania, well known for vegetable cultivation and an important area of biodiversity conservation. To obtain useful information about sustainable agriculture, management, and conservation of local pepper varieties, we analyzed the genetic diversity and conducted deep molecular characterization using whole genome resequencing (WGS) for variant/mutation detection. The pepper varieties used in the present study were registered by VRDS in the ISTIS catalog between 1974 and 2019 and maintained in conservative selection; however, no studies have been published yet using WGS analysis in order to characterize this specific germplasm. The genome sequences, annotation, and alignments provided in this study offer essential resources for genomic research as well as for future breeding efforts using the C. annuum local varieties.

Identifying low-density, ancestry-informative SNP markers through whole genome resequencing in Indian, Chinese, and wild yak

The current investigation was undertaken to elucidate the population-stratifying and ancestry-informative markers in Indian, Chinese, and wild yak populations using whole genome resequencing (WGS) analysis while employing various selection strategies (Delta, Pairwise Wright’s Fixation Index-FST, and Informativeness of Assignment) and marker densities (5–25 thousand). The study used WGS data on 105 individuals from three separate yak cohorts i.e., Indian yak (n = 29), Chinese yak (n = 61), and wild yak (n = 15). Variant calling in the GATK program with strict quality control resulted in 1,002,970 high-quality and independent (LD-pruned) SNP markers across the yak autosomes. Analysis was undertaken in toolbox for ranking and evaluation of SNPs (TRES) program wherein three different criteria i.e., Delta, Pairwise Wright’s Fixation Index-FST, and Informativeness of Assignment were employed to identify population-stratifying and ancestry-informative markers across various datasets. The top-ranked 5,000 (5K), 10,000 (10K), 15,000 (15K), 20,000 (20K), and 25,000 (25K) SNPs were identified from each dataset while their composition and performance was assessed using different criteria. The average genomic breed clustering of Indian, Chinese, and wild yak cohorts with full density dataset (105 individuals with 1,002,970 markers) was 81.74%, 80.02%, and 83.62%, respectively. Informativeness of Assignment criterion with 10K density emerged as the best combination for three yak cohorts with 86.94%, 96.46%, and 98.20% clustering for Indian, Chinese, and wild yak, respectively. There was an average increase of 7.56%, 22.72%, and 30.35% in genomic breed clustering scores of Indian, Chinese, and wild yak cohorts over the estimates of the original dataset. The selected markers showed overlap multiple protein-coding genes within a 10 kb window including ADGRB3, ANK1, CACNG7, CALN1, CHCHD2, CREBBP, GLI3, KHDRBS2, and OSBPL10. This is the first report ever on elucidating low-density SNP marker sets with population-stratifying and ancestry-informative properties in three yak groups using WGS data. The results gain significance for application of genomic selection using cost-effective low-density SNP panels in global yak species.

Research note: Whole-genome sequencing revealed genomic diversity dynamics in duck conserved populations

The purpose of this study was to comprehensively analyze the genetic diversity of the Pekin duck conserved population with five generations and to evaluate the effectiveness of the current conservation strategy. In total, 277 Pekin duck conserved individuals and 40 Mallards as ancestral controls were collected. Each duck was sequenced at about 10X whole-genome coverage, while over 7.4 million single nucleotide polymorphisms (SNPs) in total were detected for genetic diversity analysis. Both the expected heterozygosity and observed heterozygosity values exceeded 0.3. The genetic differentiation (FST) values ranged from 0.007 to 0.039, and the Polymorphism information content (PIC) values ranged from 0.29 to 0.34. These results indicate no significant differentiation between generations, and the genetic diversity remains high. In particular, the inbreeding coefficient has been strictly controlled and has not increased rapidly during the conservation. Overall, the inbreeding coefficient of the conserved Pekin duck population was higher than that of its wild ancestors, indicating that domestication has resulted in reduced genetic diversity. This is the first report using whole genome resequencing data to systematically evaluate the genomic dynamics across several generations in ducks. The results show that the strategy of free mating and random seed retention within sire families is effective for maintaining the genetic diversity of the conserved Pekin duck population.

Cleaved Amplified Polymorphic Sequence Markers in Horticultural Crops: Current Status and Future Perspectives

DNA markers have broad applications, including marker-assisted selection (MAS) for breeding new cultivars. Currently, single nucleotide polymorphisms (SNPs) have become a preferred choice of markers for molecular geneticists and breeders. They offer many advantages, such as high abundance and coverage in the genome, codominant inheritance, locus specificity, and flexibility for high-throughput genotyping/detection formats, and they are relatively inexpensive. The availability of reference genome sequences enables precise identification of candidate genes and SNPs associated with a trait of interest through quantitative trait loci (QTL) mapping and genome-wide association studies (GWAS). Such SNPs can be converted into markers for their application in MAS in crop breeding programs. Cleaved amplified polymorphic sequence (CAPS) markers amplify short genomic sequences around the polymorphic endonuclease restriction site. This review provides insight into the recent advancements made in the development and application of CAPS markers in several horticultural plants. We discussed many new tools that aid faster and more accurate design of CAPS markers from the whole genome resequencing (WGRS) data. The developed CAPS markers offer immense application in germplasm screening and field trials, genomic loci mapping, identifying candidate genes, and MAS of important horticultural traits such as disease resistance, fruit quality and morphology, and genetic purity.