Identifying SNPs associated with birth weight and days to 100 kg traits in Yorkshire pigs based on genotyping-by-sequencing

Birth weight(BW)and days to 100 kg(D100)are important economic traits that are both affected by polygenes.However,the genetic architecture of these quantitative traits is still elusive.Genotyping-by-sequencing(GBS)data containing a large number of single nucleotide polymorphisms(SNPs)have become a powerful tool in genomic analysis.To better understand their complex genetic structure,a total of 600 Yorkshire pigs were sequenced using GBS technology.After quality control,279787 SNPs were generated for subsequent genome-wide association study(GWAS).A total of 30 genome-wide SNPs(P<1.79 E–07)were identified for D100.Furthermore,a total of 22 and 2 suggestive SNPs(P<3.57 E–06)were detected for D100 and BW,respectively.Of these,one locus located on SSC12(position:46226512 bp)were evaluated to affect both BW and D100 in Yorkshire pigs,indicating the pleiotropism in different traits.Considering the function of candidate genes,two genes,NSRP1 and DOCK7,were suggested as the most promising candidate genes involved in growth traits.Thus,use of GBS is able to identify novel variants and potential candidate genes for BW and D100,and provide an opportunity for improving pig growth traits using genomic selection in pigs.

Reveal the Population Genetic Characteristics of Bombay Duck (Harpadon nehereus) in Coastal Waters of China with Genotyping-by-Sequencing Technique

Bombay duck(Harpadon nehereus)is an economically important species in the estuarine and coastal offshore waters of the Indo-West Pacific.This study aims to reveal the genome-wide genetic characteristics of five populations of H.nehereus from the coastal areas of China by using the genotyping-by-sequencing technique.After strict filtering,32088 high-quality single-nucleotide polymorphism markers were detected and analyzed.The average observed heterozygosity and expected heterozygosity ranged from 0.41651 to 0.56725 and from 0.30998 to 0.45531,respectively,indicating that heterozygosity excess occurred in H.nehereus populations.The nucleotide diversity ranged from 0.63664 to 0.74868,which was larger than those from other marine fishes.No obvious genetic structure was detected among H.nehereus populations,and the genetic variation originated within individuals.Extensive gene exchange caused by longshore currents in the reproductive season might be the primary reason for the weak genetic differentiation.Among various environmental factors,water temperature might be the key element affecting the genetic structure of H.nehereus.Due to the destruction and overfishing of spawning grounds,the fishery resources declined in recent years.This study could serve as a reference for the resource protection and rational utilization of H.nehereus.

Genomic location of Gb1, a unique gene conferring wheat resistance to greenbug biotype F

Greenbug(Schizaphis graminum, Rondani) is a serious insect pest in many wheat growing regions and has been infesting cereal crops in the USA for over a century. Continuous occurrence of new greenbug biotypes makes it essential to explore all greenbug resistant sources available to manage this pest. Gb1, a recessive greenbug resistance gene in DS28A, confers resistance to several economically important greenbug biotypes and is the only gene found to be resistant to greenbug biotype F. A set of 174 F_(2:3)lines from the cross DS28A × Custer was evaluated for resistance to greenbug biotype F in 2020 and 2022. Selective genotyping of the corresponding F_(2) population using single nucleotide polymorphism(SNP) markers generated by genotyping-by-sequencing(GBS) led to the identification of a candidate genomic region for Gb1. Thus, SSR markers previously mapped in this region were used to genotype the entire F2population,and kompetitive allele specific PCR(KASP) markers were also developed from SNPs in the target region.Gb1 was placed in the terminal region of the short arm of chromosome 1A, and its location was confirmed in a second population derived from the cross DS28A × PI 697274. The combined data analysis from the two mapping populations delimited Gb1 to a < 1 Mb interval between 13,328,200 and 14,241,426 bp on1AS.

基于GBS技术的籼稻种质资源SNPs和Haplotype分析

利用GBS技术(NlaⅢ和MseⅠ分别酶切)对198份(112份恢复系,49份保持系和37份不明恢保关系材料)陕西省主要籼稻种质资源进行测序,MAF 0.05过滤,获得91421 SNPs,构建6981个Haplotype。采用MEGA5、PLINKv 1.07、TASSEL 5.0等生物学主流软件和R语言,进行籼稻群体的SNPs和Haplotype在全基因组的分布特点、群体遗传结构及全基因组KEGG分析。分布在籼稻12个连锁群上的SNPs和Haplotype的多态性及密度都不同。主成分、UPGMA及K聚类都表明198个籼稻的遗传基础较单一,样本间的遗传距离为0.01~0.60,平均遗传距离为0.28。籼稻全基因组注释基因主要参与核糖体、植物激素信号转导和内质网蛋白质加工信号通路。平均每4374 bp有1个SNP。198个籼稻组成的自然群体分层不明显,可以作为后续QTLs的定位群体。不同连锁群上编码的基因行使的主要生物学功能差异明显。

Meta-analysis of QTL for Fusarium head blight resistance in Chinese wheat landraces

Epidemics of Fusarium head blight(FHB), incited by Fusarium graminearum Schwabe, in wheat cause significant reductions in grain yield and quality. Numerous quantitative trait loci(QTL) for FHB resistance have been reported from Chinese sources. However, the relationships among QTL from different landraces have not been characterized. We earlier mapped QTL for FHB resistance using low-density maps developed from five recombinant inbred line(RIL) populations involving Chinese landraces ‘Haiyanzhong’(HYZ),‘Wangshuibai’(WSB), ‘Baishanyuehuang’(BSYH), ‘Huangfangzhu’(HFZ), and‘Huangcandou’(HCD) as FHB resistant parents. In this study, we used maps of single nucleotide polymorphisms(SNP) developed from the five populations and identified 31 QTL on 16 chromosomes;10 QTL were new. We constructed a consensus map and identified six meta-QTL(MQTL) and SNP within the MQTL regions using meta-analysis. Two of the MQTL were on chromosome 3 BS(3 BSd and 3 BSc), and one on each of chromosomes 3A, 2D, 3D,and 4D. Twenty-two SNP closely linked to MQTL were converted into breeder friendly Kompetitive Allele Specific Polymerase Chain Reaction(KASP) assays, which should be useful for marker-assisted selection in breeding programs.

Construction of high-density SNP genetic maps and QTL mapping for dwarf-related traits in Litchi chinensis Sonn

Litchi chinensis Sonn is widely cultivated in subtropical regions and has an important economic value.A high-density genetic map is a valuable tool for mapping quantitative trait loci(QTL)and marker-assisted breeding programs.In this study,a single nucleotide polymorphism(SNP)-based high-density linkage map was constructed by a genotyping-by-sequencing(GBS)protocol using an F1 population of 178 progenies between two commercial litchi cultivars,‘Ziniangxi’(dwarf)and‘Feizixiao’(vigorous).The genetic map consisted of 3027 SNP markers with a total length of 1711.97 cM in 15 linkage groups(LGs)and an average marker distance of 0.57 cM.Based on this high-density linkage map and three years of phenotyping,a total of 37 QTLs were detected for eight dwarf-related traits,including length of new branch(LNB),diameter of new branch(DNB),length of common petiole(LCP),diameter of common petiole(DCP),length of internode(LI),length of single leaf(LSL),width of single leaf(WSL),and plant height(PH).These QTLs could explain 8.0 to 14.7%(mean=9.7%)of the phenotypic variation.Among them,several QTL clusters were observed,particularly on LG04 and LG11,which might show enrichment for genes regulating the dwarf-related traits in litchi.There were 126 candidate genes identified within the QTL regions,55 of which are differentially expressed genes by RNA-seq analysis between‘Ziniangxi’and‘Feizixiao’.These DEGs were found to participate in the regulation of cell development,material transportation,signal transduction,and plant morphogenesis,so they might play important roles in regulating plant dwarf-related traits.The high-density genetic map and QTLs identification related to dwarf traits can provide a valuable genetic resource and a basis for marker-assisted selection and genomic studies of litchi.

Crop Breeding Chips and Genotyping Platforms： Progress, Challenges, and Perspectives

There is a rapidly rising trend in the development and application of molecular marker assays for gene map- ping and discovery in field crops and trees. Thus far, more than 50 SNP arrays and 15 different types of genotyping-by-sequencing （GBS） platforms have been developed in over 25 crop species and perennial trees. However, much less effort has been made on developing ultra-high-throughput and cost-effective genotyping platforms for applied breeding programs. In this review, we discuss the scientific bottlenecks in existing SNP arrays and GBS technologies and the strategies to develop targeted platforms for crop mo- lecular breeding. We propose that future practical breeding platforms should adopt automated genotyping technologies, either array or sequencing based, target functional polymorphisms underpinning economic traits, and provide desirable prediction accuracy for quantitative traits, with universal applications under wide genetic backgrounds in crops. The development of such platforms faces serious challenges at both the technological level due to cost ineffectiveness, and the knowledge level due to large genotype- phenotype gaps in crop plants. It is expected that such genotyping platforms will be achieved in the next ten years in major crops in consideration of （a） rapid development in gene discovery of important traits, （b） deepened understanding of quantitative traits through new analytical models and population designs, （c） integration of multi-layer -omics data leading to identification of genes and pathways responsible for important breeding traits, and （d） improvement in cost effectiveness of large-scale genotyping. Crop breeding chips and genotyping platforms will provide unprecedented opportunities to accelerate the development of cultivars with desired yield potential, quality, and enhanced adaptation to mitigate the effects of climate change.

Bulbosum to Go： A Toolbox to Utilize Hordeum vulgarelbulbosum Introgressions for Breeding and Beyond

Hordeum bulbosum L., a wild relative of barley （Hordeum vulgare L.）, has been considered as a valuable source of genetic diversity for barley improvement. Since the 1990s, a considerable number of barley/H, bulbosum introgression lines （IL）s has been generated, with segments introgressed from H. bulbosum harboring a diverse set of desirable traits. However, the efficient utilization of these ILs has been hampered, largely due to the lack of suitable molecular tools for their genetic characterization and highly reduced interspecific recombination frequencies in the region of the introgression. In the present study, we utilized genotyping-by-sequencing for the detailed molecular characterization of 145 ILs. Genotypic information allows the genetic diversity within the set of ILs to be determined and a strategy was outlined to tackle the obstacle of reduced recombination frequencies. Furthermore, we compiled exome capture re-sequencing information of barley and H. bulbosum and designed an integrated barley/ H. bulbosum sequence resource with polymorphism information on interspecific and intraspecific sequence variations of both species. The integrated sequence will be valuable for marker development in barley/H, bulbosum ILs derived from any barley and H. bulbosum donors. This study provides the tools for the widespread utilization of barley/H, bulbosum ILs in applied barley breeding and academic research.

Regulation of root secondary metabolites by partial root-associated microbiotas under the shaping of licorice ecotypic differentiation in northwest China

Interactions between plant hosts and their microbiotas are becoming increasingly evident,while the effects of plant communities on microbial communities in different geographic environments are poorly understood.Here,the differentiation of licorice plant ecotypes and the distribution of rootassociated microbiotas were investigated across five sampling sites in northwest China.The interactions between the environment,plant and microbial communities,and their effects on licorice root secondary metabolites,were elucidated.The plant community was clearly differentiated into distinct ecotypes based on genotyping-by-sequencing and was primarily driven by geographic distance and available soil nitrogen.The bulk soil and rootassociated microbiotas(rhizosphere soil and root endosphere)partially correlated with plant community,but all were significantly discriminated by plant clade.Moreover,these microbiotas were explained to different extents by distinct combinations of environment,geography,and plant community.Similarly,three structural equation models showed that licorice root secondary metabolites were complicatedly modulated by multiple abiotic and biotic factors,and were mostly explained by these factors in the rhizosphere model.Collectively,the results provide novel insights into the role of environment–plant–microbiota interactions in regulating root secondary metabolites.That should be accounted for when selecting appropriate licorice planting sites and management measures.

Genome-wide association study identifies loci for body shape in the large yellow croaker(Larimichthys crocea)

The large yellow croaker(Larimichthys crocea)is an important maricultured fish species in southeast China.Body shape is an important economic trait for this species,because consumers prefer to purchase fish that have a slender shape.Furthermore,investigating the genetic basis of this trait may be useful for understanding the evolution of fish body shape in general.This study randomly selected 500 large yellow croakers to perform genome-wide association study of this trait.We used Genotyping-By-Sequencing technology combined with a genome-wide prediction model(BayesC)to identify and test QTLs.We also compared the association results using BayesC and single-marker analysis,and found that BayesC outperformed single-marker analysis in detecting significant SNPs explaining a proportion of the total genetic variance in this experiment.Using 124,419 SNP markers,10 candidate genes,correspond to 4 QTL regions located around 3.5,1.8,23.9 and 10.8 Mb on chromosomes 2,4,8 and 22 respectively,were suggested to be relevant to the trait.All of these genes may directly or indirectly participate in bone development.These genes may provide a valuable reference for marker-assisted selective breeding and investigating the genetic basis of the evolution of fish body shape.