Rapid vertebrate speciation via isolation, bottlenecks, and drift.

Speciation is often driven by selective processes like those associated with viability, mate choice, or local adaptation, and "speciation genes" have been identified in many eukaryotic lineages. In contrast, neutral processes are rarely considered as the primary drivers of speciation, especially over short evolutionary timeframes. Here, we describe a rapid vertebrate speciation event driven primarily by genetic drift. The White Sands pupfish (Cyprinodon tularosa) is endemic to New Mexico's Tularosa Basin where the species is currently managed as two Evolutionarily significant units (ESUs) and is of international conservation concern (Endangered). Whole-genome resequencing data from each ESU showed remarkably high and uniform levels of differentiation across the entire genome (global FST ≈ 0.40). Despite inhabiting ecologically dissimilar springs and streams, our whole-genome analysis revealed no discrete islands of divergence indicative of strong selection, even when we focused on an array of candidate genes. Demographic modeling of the joint allele frequency spectrum indicates the two ESUs split only ~4 to 5 kya and that both ESUs have undergone major bottlenecks within the last 2.5 millennia. Our results indicate the genome-wide disparities between the two ESUs are not driven by divergent selection but by neutral drift due to small population sizes, geographic isolation, and repeated bottlenecks. While rapid speciation is often driven by natural or sexual selection, here we show that isolation and drift have led to speciation within a few thousand generations. We discuss these evolutionary insights in light of the conservation management challenges they pose.

Microevolutionary change in wild stickleback: Using integrative time-series data to infer responses to selection.

A central goal in evolutionary biology is to understand how different evolutionary processes cause trait change in wild populations. However, quantifying evolutionary change in the wild requires linking trait change to shifts in allele frequencies at causal loci. Nevertheless, datasets that allow for such tests are extremely rare and existing theoretical approaches poorly account for the evolutionary dynamics that likely occur in ecological settings. Using a decade-long integrative phenome-to-genome time-series dataset on wild threespine stickleback (Gasterosteus aculeatus), we identified how different modes of selection (directional, episodic, and balancing) drive microevolutionary change in correlated traits over time. Most strikingly, we show that feeding traits changed by as much 25% across 10 generations which was driven by changes in the genetic architecture (i.e., in both genomic breeding values and allele frequencies at genetic loci for feeding traits). Importantly, allele frequencies at genetic loci related to feeding traits changed at a rate greater than expected under drift, suggesting that the observed change was a result of directional selection. Allele frequency dynamics of loci related to swimming traits appeared to be under fluctuating selection evident in periodic population crashes in this system. Our results show that microevolutionary change in a wild population is characterized by different modes of selection acting simultaneously on different traits, which likely has important consequences for the evolution of correlated traits. Our study provides one of the most thorough descriptions to date of how microevolutionary processes result in trait change in a natural population.

Standing genetic variation and chromosome differences drove rapid ecotype formation in a major malaria mosquito.

Species distributed across heterogeneous environments often evolve locally adapted ecotypes, but understanding of the genetic mechanisms involved in their formation and maintenance in the face of gene flow is incomplete. In Burkina Faso, the major African malaria mosquito Anopheles funestus comprises two strictly sympatric and morphologically indistinguishable yet karyotypically differentiated forms reported to differ in ecology and behavior. However, knowledge of the genetic basis and environmental determinants of An. funestus diversification was impeded by lack of modern genomic resources. Here, we applied deep whole-genome sequencing and analysis to test the hypothesis that these two forms are ecotypes differentially adapted to breeding in natural swamps versus irrigated rice fields. We demonstrate genome-wide differentiation despite extensive microsympatry, synchronicity, and ongoing hybridization. Demographic inference supports a split only ~1,300 y ago, closely following the massive expansion of domesticated African rice cultivation ~1,850 y ago. Regions of highest divergence, concentrated in chromosomal inversions, were under selection during lineage splitting, consistent with local adaptation. The origin of nearly all variations implicated in adaptation, including chromosomal inversions, substantially predates the ecotype split, suggesting that rapid adaptation was fueled mainly by standing genetic variation. Sharp inversion frequency differences likely facilitated adaptive divergence between ecotypes by suppressing recombination between opposing chromosomal orientations of the two ecotypes, while permitting free recombination within the structurally monomorphic rice ecotype. Our results align with growing evidence from diverse taxa that rapid ecological diversification can arise from evolutionarily old structural genetic variants that modify genetic recombination.

A large sequenced mutant library - valuable reverse genetic resource that covers 98% of sorghum genes.

Mutant populations are crucial for functional genomics and discovering novel traits for crop breeding. Sorghum, a drought and heat-tolerant C4 species, requires a vast, large-scale, annotated, and sequenced mutant resource to enhance crop improvement through functional genomics research. Here, we report a sorghum large-scale sequenced mutant population with 9.5 million ethyl methane sulfonate (EMS)-induced mutations that covered 98% of sorghum's annotated genes using inbred line BTx623. Remarkably, a total of 610 320 mutations within the promoter and enhancer regions of 18 000 and 11 790 genes, respectively, can be leveraged for novel research of cis-regulatory elements. A comparison of the distribution of mutations in the large-scale mutant library and sorghum association panel (SAP) provides insights into the influence of selection. EMS-induced mutations appeared to be random across different regions of the genome without significant enrichment in different sections of a gene, including the 5' UTR, gene body, and 3'-UTR. In contrast, there were low variation density in the coding and UTR regions in the SAP. Based on the Ka /Ks value, the mutant library (~1) experienced little selection, unlike the SAP (0.40), which has been strongly selected through breeding. All mutation data are publicly searchable through SorbMutDB (https://www.depts.ttu.edu/igcast/sorbmutdb.php) and SorghumBase (https://sorghumbase.org/). This current large-scale sequence-indexed sorghum mutant population is a crucial resource that enriched the sorghum gene pool with novel diversity and a highly valuable tool for the Poaceae family, that will advance plant biology research and crop breeding.

Whole-genome resequencing facilitates the development of a 50K single nucleotide polymorphism genotyping array for Scots pine (Pinus sylvestris L.) and its transferability to other pine species.

Scots pine (Pinus sylvestris L.) is one of the most widespread and economically important conifer species in the world. Applications like genomic selection and association studies, which could help accelerate breeding cycles, are challenging in Scots pine because of its large and repetitive genome. For this reason, genotyping tools for conifer species, and in particular for Scots pine, are commonly based on transcribed regions of the genome. In this article, we present the Axiom Psyl50K array, the first single nucleotide polymorphism (SNP) genotyping array for Scots pine based on whole-genome resequencing, that represents both genic and intergenic regions. This array was designed following a two-step procedure: first, 192 trees were sequenced, and a 430K SNP screening array was constructed. Then, 480 samples, including haploid megagametophytes, full-sib family trios, breeding population, and range-wide individuals from across Eurasia were genotyped with the screening array. The best 50K SNPs were selected based on quality, replicability, distribution across the draft genome assembly, balance between genic and intergenic regions, and genotype-environment and genotype-phenotype associations. Of the final 49 877 probes tiled in the array, 20 372 (40.84%) occur inside gene models, while the rest lie in intergenic regions. We also show that the Psyl50K array can yield enough high-confidence SNPs for genetic studies in pine species from North America and Eurasia. This new genotyping tool will be a valuable resource for high-throughput fundamental and applied research of Scots pine and other pine species.

Introgression drives adaptation to the plateau environment in a subterranean rodent.

BACKGROUND: Introgression has repeatedly been shown to play an important role in the adaptation of species to extreme environments, yet how introgression enables rodents with specialized subterranean lifestyle to acclimatize to high altitudes is still unclear. Myospalacinae is a group of subterranean rodents, among which the high-altitude plateau zokors (Eospalax baileyi) and the low-altitude Gansu zokors (E. cansus) are sympatrically distributed in the grassland ecosystems of the Qinghai-Tibet Plateau (QTP). Together, they provide a model for the study of the role of introgression in the adaptation of low-altitude subterranean rodents to high altitudes. RESULTS: Applying low-coverage whole-genome resequencing and population genetics analyses, we identified evidence of adaptive introgression from plateau zokors into Gansu zokors, which likely facilitated the adaptation of the latter to the high-altitude environment of the QTP. We identified positively selected genes with functions related to energy metabolism, cardiovascular system development, calcium ion transport, and response to hypoxia which likely made critical contributions to adaptation to the plateau environment in both plateau zokors and high-altitude populations of Gansu zokors. CONCLUSIONS: Introgression of genes associated with hypoxia adaptation from plateau zokors may have played a role in the adaptation of Gansu zokors to the plateau environment. Our study provides new insights into the understanding of adaptive evolution of species on the QTP and the importance of introgression in the adaptation of species to high-altitude environments.

Genetic structure analysis of yak breeds and their response to adaptive evolution.

Yaks are crucial genetic resources in the Tibetan Plateau and surrounding regions. Throughout the long process of domestication, natural and artificial selection pressures have enabled yaks to demonstrate adaptive characteristics to the environment in terms of physiological structure and genetic molecules, but no systematic cell analysis has been carried out on this phenomenon of yaks. Here, the population structure and genetic diversity of yak were studied by WGRS, and the genes related to yak adaptability were excavated. Combined with scRNA-seq method, the transcription map of yak lung tissue and skin tissue was constructed, which provided a new comprehensive insight into yak adaptability. The analysis of yak population structure showed that there was obvious genetic differentiation between TZ _ yak and other seven yak populations, while there was significant genetic exchange between PL _ yak and SB _ yak at high altitude. WGRS and scRNA-seq analysis revealed that the gene HIF1A related to high altitude adaptation was expressed in various cell types, while EPAS1 was predominantly expressed in epithelial and endothelial cells of yak lung tissue. Endothelial cells play a critical role in hypoxia-adapted VEGF signaling, which correlates closely with the high expression of KDR and VEGFA genes in endothelial cells and monocytes. Furthermore, in the selection signal of High _ yak vs Low _ yak, 19.8 % of the genes overlapped with the genes screened by skin scRNA-seq, including genes related to coat color such as RORA, BNC2, and KIT. Notably, BNC2 is a gene associated with melanin deposition and shows high expression levels in HS cells. Additionally, GRN in melanocytes and SORT1 in IRS play an important role in cell communication between melanocytes and IRS. These findings offer new insights into the natural polymorphism of yaks and provide a valuable reference for future research on high-altitude mammals, and potentially even human genetics.

Deepening genomic sequences of 1081 Gossypium hirsutum accessions reveals novel SNPs and haplotypes relevant for practical breeding utility.

Fiber quality is a major breeding goal in cotton, but phenotypically direct selection is often hindered. In this study, we identified fiber quality and yield related loci using GWAS based on 2.97 million SNPs obtained from 10.65× resequencing data of 1081 accessions. The results showed that 585 novel fiber loci, including two novel stable SNP peaks associated with fiber length on chromosomes At12 and Dt05 and one novel genome regions linked with fiber strength on chromosome Dt12 were identified. Furthermore, by means of gene expression analysis, GhM_A12G0090, GhM_D05G1692, GhM_D12G3135 were identified and GhM_D11G2208 function was identified in Arabidopsis. Additionally, 14 consistent and stable superior haplotypes were identified, and 25 accessions were detected as possessing these 14 superior haplotype in breeding. This study providing fundamental insight relevant to identification of genes associated with fiber quality and yield will enhance future efforts toward improvement of upland cotton.

Whole-genome resequencing and RNA-seq analysis implicates GPR75 as a potential genetic basis related to retarded growth in South China carp (Cyprinus carpio rubrofuscus).

The south China carp (Cyprinus carpio rubrofuscus) is an indigenous and important fish species, widely cultured in south China. However, part of individuals experienced retarded growth, the genetic basis of which has yet to be elucidated. In this study, whole-genome resequencing of 35 fast-growing and 35 retarded-growing south China carp were conducted to identify promising genes associated with retarded growth. Twelve candidate SNPs were detected and annotated to the Gpr75 gene, which has been reported to be related with body weight through regulating insulin homeostasis. RNA-seq analysis of muscle suggested that differentially expressed genes were significantly enriched in the insulin signaling pathway. Additionally, the fasting serum insulin level was significantly lower while the blood glucose level was significantly higher in the retarded-growing group. Our preliminary study provides insights into the genetic basis underlying the retarded growth and may facilitate further genetic improvement of south China carp.

A common resequencing-based genetic marker data set for global maize diversity.

Maize (Zea mays ssp. mays) populations exhibit vast ranges of genetic and phenotypic diversity. As sequencing costs have declined, an increasing number of projects have sought to measure genetic differences between and within maize populations using whole-genome resequencing strategies, identifying millions of segregating single-nucleotide polymorphisms (SNPs) and insertions/deletions (InDels). Unlike older genotyping strategies like microarrays and genotyping by sequencing, resequencing should, in principle, frequently identify and score common genetic variants. However, in practice, different projects frequently employ different analytical pipelines, often employ different reference genome assemblies and consistently filter for minor allele frequency within the study population. This constrains the potential to reuse and remix data on genetic diversity generated from different projects to address new biological questions in new ways. Here, we employ resequencing data from 1276 previously published maize samples and 239 newly resequenced maize samples to generate a single unified marker set of approximately 366 million segregating variants and approximately 46 million high-confidence variants scored across crop wild relatives, landraces as well as tropical and temperate lines from different breeding eras. We demonstrate that the new variant set provides increased power to identify known causal flowering-time genes using previously published trait data sets, as well as the potential to track changes in the frequency of functionally distinct alleles across the global distribution of modern maize.

Genome-wide association studies of body size traits in Tibetan sheep.

BACKGROUND: Elucidating the genetic variation underlying phenotypic diversity will facilitate improving production performance in livestock species. The Tibetan sheep breed in China holds significant historical importance, serving as a fundamental pillar of Qinghai's animal husbandry sector. The Plateau-type Tibetan sheep, comprising 90% of the province's population, are characterized by their tall stature and serve as the primary breed among Tibetan sheep. In contrast, Zhashijia sheep exhibit larger size and superior meat quality. These two species provide an excellent model for elucidating the genetic basis of body size variation. Therefore, this study aims to conduct a comprehensive genome-wide association study on these two Tibetan sheep breeds to identify single nucleotide polymorphism loci and regulatory genes that influence body size traits in Tibetan sheep. RESULT: In this study, the phenotypic traits of body weight, body length, body height, chest circumference, chest depth, chest width, waist angle width, and pipe circumference were evaluated in two Tibetan sheep breeds: Plateau-type sheep and Zhashijia Tibetan sheep. Whole genome sequencing generated 48,215,130 high-quality SNPs for genome-wide association study. Four methods were applied and identified 623 SNPs significantly associated with body size traits. The significantly associated single nucleotide polymorphisms identified in this study are located near or within 111 candidate genes. These genes exhibit enrichment in the cAMP and Rap1 signaling pathways, significantly affecting animal growth, and body size. Specifically, the following genes were associated: ASAP1, CDK6, FRYL, NAV2, PTPRM, GPC6, PTPRG, KANK1, NTRK2 and ADCY8. CONCLUSION: By genome-wide association study, we identified 16 SNPs and 10 candidate genes associated with body size traits in Tibetan sheep, which hold potential for application in genomic selection breeding programs in sheep. Identifying these candidate genes will establish a solid foundation for applying molecular marker-assisted selection in sheep breeding and improve our understanding of body size control in farmed animals.

Comparative whole-genome resequencing to uncover selection signatures linked to litter size in Hu Sheep and five other breeds.

Hu sheep (HS), a breed of sheep carrying the FecB mutation gene, is known for its "year-round estrus and multiple births" and is an ideal model for studying the high fecundity mechanisms of livestock. Through analyzing and comparing the genomic selection features of Hu sheep and other sheep breeds, we identified a series of candidate genes that may play a role in Hu sheep's high fecundity mechanisms. In this study, we conducted whole-genome resequencing on six breeds and screened key mutations significantly correlated with high reproductive traits in sheep. Notably, the CC2D1B gene was selected by the fixation index (FST) and the cross-population composite likelihood ratio (XP-CLR) methods in HS and other five breeds. It was worth noting that the CC2D1B gene in HS was different from that in other sheep breeds, and seven missense mutations have been identified. Furthermore, the linkage disequilibrium (LD) analysis revealed a strong linkage disequilibrium in this specific gene region. Subsequently, by performing different grouping based on FecB genotypes in Hu sheep, genome-wide selective signal analysis screened several genes related to reproduction, such as BMPR1B and PPM1K. Besides, FST analysis identified functional genes related to reproductive traits, including RHEB, HSPA2, PPP1CC, HVCN1, and CCDC63. Additionally, a missense mutation was found in the CCDC63 gene and the haplotype was different between the high reproduction (HR) group and low reproduction (LR) group in HS. In summary, we discovered genetic differentiation among six distinct breeding sheep breeds at the whole genome level. Additionally, we identified a set of genes which were associated with reproductive performance in Hu sheep and visualized how these genes differed in different breeds. These findings laid a theoretical foundation for understanding genetic mechanisms behind high prolific traits in sheep.

Selection signatures of wool color in Gangba sheep revealed by genome-wide SNP discovery.

BACKGROUND: Gangba sheep as a famous breed of Tibetan sheep, its wool color is mainly white and black. Gangba wool is economically important as a high-quality raw material for Tibetan blankets and Tibetan serge. However, relatively few studies have been conducted on the wool color of Tibetan sheep. RESULTS: To fill this research gap, this study conducted an in-depth analysis of two populations of Gangba sheep (black and white wool color) using whole genome resequencing to identify genetic variation associated with wool color. Utilizing PCA, Genetic Admixture, and N-J Tree analyses, the present study revealed a consistent genetic relationship and structure between black and white wool colored Gangba sheep populations, which is consistent with their breed history. Analysis of selection signatures using multiple methods (FST, π ratio, Tajima's D), 370 candidate genes were screened in the black wool group (GBB vs GBW); among them, MC1R, MLPH, SPIRE2, RAB17, SMARCA4, IRF4, CAV1, USP7, TP53, MYO6, MITF, MC2R, TET2, NF1, JAK1, GABRR1 genes are mainly associated with melanin synthesis, melanin delivery, and distribution. The enrichment results of the candidate genes identified 35 GO entries and 19 KEGG pathways associated with the formation of the black phenotype. 311 candidate genes were screened in the white wool group (GBW vs GBB); among them, REST, POU2F1, ADCY10, CCNB1, EP300, BRD4, GLI3, and SDHA genes were mainly associated with interfering with the differentiation of neural crest cells into melanocytes, affecting the proliferation of melanocytes, and inhibiting melanin synthesis. 31 GO entries and 22 KEGG pathways were associated with the formation of the white phenotype. CONCLUSIONS: This study provides important information for understanding the genetic mechanism of wool color in Gangba, and provides genetic knowledge for improving and optimizing the wool color of Tibetan sheep. Genetic improvement and selective breeding to produce wool of specific colors can meet the demand for a diversity of wool products in the Tibetan wool textile market.

Population structure and adaptability analysis of Schizothorax o'connori based on whole-genome resequencing.

BACKGROUND: Schizothorax o'connori is an endemic fish distributed in the upper and lower reaches of the Yarlung Zangbo River in China. It has experienced a fourth round of whole gene replication events and is a good model for exploring the genetic differentiation and environmental adaptability of fish in the Qinghai-Tibet Plateau. The uplift of the Qinghai-Tibet Plateau has led to changes in the river system, thereby affecting gene exchange and population differentiation between fish populations. With the release of fish whole genome data, whole genome resequencing has been widely used in genetic evolutionary analysis and screening of selected genes in fish, which can better elucidate the genetic basis and molecular environmental adaptation mechanisms of fish. Therefore, our purpose of this study was to understand the population structure and adaptive characteristics of S. o'connori using the whole-genome resequencing method. RESULTS: The results showed that 23,602,746 SNPs were identified from seven populations, mostly distributed on chromosomes 2 and 23. There was no significant genetic differentiation between the populations, and the genetic diversity was relatively low. However, the Zangga population could be separated from the Bomi, Linzhi, and Milin populations in the cluster analysis. Based on historical dynamics analysis of the population, the size of the ancestral population of S. o'connori was affected by the late accelerated uplift of the Qinghai Tibet Plateau and the Fourth Glacial Age. The selected sites were mostly enriched in pathways related to DNA repair and energy metabolism. CONCLUSION: Overall, the whole-genome resequencing analysis provides valuable insights into the population structure and adaptive characteristics of S. o'connori. There was no obvious genetic differentiation at the genome level between the S. o'connori populations upstream and downstream of the Yarlung Zangbo River. The current distribution pattern and genetic diversity are influenced by the late accelerated uplift of the Qinghai Tibet Plateau and the Fourth Ice Age. The selected sites of S. o'connori are enriched in the energy metabolism and DNA repair pathways to adapt to the low temperature and strong ultraviolet radiation environment at high altitude.

Identification of the genetic characteristics of copy number variations in experimental specific pathogen-free ducks using whole-genome resequencing.

BACKGROUND: Specific pathogen-free ducks are a valuable laboratory resource for waterfowl disease research and poultry vaccine development. High throughput sequencing allows the systematic identification of structural variants in genomes. Copy number variation (CNV) can explain the variation of important duck genetic traits. Herein, the genome-wide CNVs of the three experimental duck species in China (Jinding ducks (JD), Shaoxing ducks (SX), and Fujian Shanma ducks (SM)) were characterized using resequencing to determine their genetic characteristics and selection signatures. RESULTS: We obtained 4,810 CNV regions (CNVRs) by merging 73,012 CNVs, covering 4.2% of the duck genome. Functional analysis revealed that the shared CNVR-harbored genes were significantly enriched for 31 gene ontology terms and 16 Kyoto Encyclopedia of Genes and Genomes pathways (e.g., olfactory transduction and immune system). Based on the genome-wide fixation index for each CNVR, growth (SPAG17 and PTH1R), disease resistance (CATHL3 and DMBT1), and thermoregulation (TRPC4 and SLIT3) candidate genes were identified in strongly selected signatures specific to JD, SM, and SX, respectively. CONCLUSIONS: In conclusion, we investigated the genome-wide distribution of experimental duck CNVs, providing a reference to establish the genetic basis of different phenotypic traits, thus contributing to the management of experimental animal genetic resources.

Distinct structural variants and repeat landscape shape the genomes of the ancient grapes Aglianico and Falanghina.

Mounting evidence recognizes structural variations (SVs) and repetitive DNA sequences as crucial players in shaping the existing grape phenotypic diversity at intra- and inter-species levels. To deepen our understanding on the abundance, diversity, and distribution of SVs and repetitive DNAs, including transposable elements (TEs) and tandemly repeated satellite DNA (satDNAs), we re-sequenced the genomes of the ancient grapes Aglianico and Falanghina. The analysis of large copy number variants (CNVs) detected candidate polymorphic genes that are involved in the enological features of these varieties. In a comparative analysis of Aglianico and Falanghina sequences with 21 publicly available genomes of cultivated grapes, we provided a genome-wide annotation of grape TEs at the lineage level. We disclosed that at least two main clusters of grape cultivars could be identified based on the TEs content. Multiple TEs families appeared either significantly enriched or depleted. In addition, in silico and cytological analyses provided evidence for a diverse chromosomal distribution of several satellite repeats between Aglianico, Falanghina, and other grapes. Overall, our data further improved our understanding of the intricate grape diversity held by two Italian traditional varieties, unveiling a pool of unique candidate genes never so far exploited in breeding for improved fruit quality.

Genome-wide association study and development of molecular markers for yield and quality traits in peanut (Arachis hypogaea L.).

BACKGROUND: This study aims to decipher the genetic basis governing yield components and quality attributes of peanuts, a critical aspect for advancing molecular breeding techniques. Integrating genotype re-sequencing and phenotypic evaluations of seven yield components and two grain quality traits across four distinct environments allowed for the execution of a genome-wide association study (GWAS). RESULTS: The nine phenotypic traits were all continuous and followed a normal distribution. The broad heritability ranged from 88.09 to 98.08%, and the genotype-environment interaction effects were all significant. There was a highly significant negative correlation between protein content (PC) and oil content (OC). The 10× genome re-sequencing of 199 peanut accessions yielded a total of 631,988 high-quality single nucleotide polymorphisms (SNPs), with 374 significant SNP loci identified in association with the nine traits of interest. Notably, 66 of these pertinent SNPs were detected in multiple environments, and 48 of them were linked to multiple traits of interest. Five loci situated on chromosome 16 (Chr16) exhibited pleiotropic effects on yield traits, accounting for 17.64-32.61% of the observed phenotypic variation. Two loci on Chr08 were found to be strongly associated with protein and oil contents, accounting for 12.86% and 14.06% of their respective phenotypic variations, respectively. Linkage disequilibrium (LD) block analysis of these seven loci unraveled five nonsynonymous variants, leading to the identification of one yield-related candidate gene and two quality-related candidate genes. The correlation between phenotypic variation and SNP loci in these candidate genes was validated by Kompetitive allele-specific PCR (KASP) marker analysis. CONCLUSIONS: Overall, molecular markers were developed for genetic loci associated with yield and quality traits through a GWAS investigation of 199 peanut accessions across four distinct environments. These molecular tools can aid in the development of desirable peanut germplasm with an equilibrium of yield and quality through marker-assisted breeding.

Multi-omics identification of a key glycosyl hydrolase gene FtGH1 involved in rutin hydrolysis in Tartary buckwheat (Fagopyrum tataricum).

Rutin, a flavonoid rich in buckwheat, is important for human health and plant resistance to external stresses. The hydrolysis of rutin to quercetin underlies the bitter taste of Tartary buckwheat. In order to identify rutin hydrolysis genes, a 200 genotypes mini-core Tartary buckwheat germplasm resource was re-sequenced with 30-fold coverage depth. By combining the content of the intermediate metabolites of rutin metabolism with genome resequencing data, metabolite genome-wide association analyses (GWAS) eventually identified a glycosyl hydrolase gene FtGH1, which could hydrolyse rutin to quercetin. This function was validated both in Tartary buckwheat overexpression hairy roots and in vitro enzyme activity assays. Mutation of the two key active sites, which were determined by molecular docking and experimentally verified via overexpression in hairy roots and transient expression in tobacco leaves, exhibited abnormal subcellular localization, suggesting functional changes. Sequence analysis revealed that mutation of the FtGH1 promoter in accessions of two haplotypes might be necessary for enzymatic activity. Co-expression analysis and GWAS revealed that FtbHLH165 not only repressed FtGH1 expression, but also increased seed length. This work reveals a potential mechanism behind rutin metabolism, which should provide both theoretical support in the study of flavonoid metabolism and in the molecular breeding of Tartary buckwheat.

Evolutionary relationship of moso bamboo forms and a multihormone regulatory cascade involving culm shape variation.

Moso bamboo (Phyllostachys edulis) known as Mao Zhu (MZ) in Chinese exhibits various forms with distinct morphological characteristics. However, the evolutionary relationship among MZ forms and the mechanisms of culm shape variation are still lacking. Here, the main differences among MZ forms were identified as culm shape variation, which were confirmed by analysing MZ forms (799 bamboo culms) and MZ (458 bamboo culms) populations. To unravel the genetic basis underlying the morphological variations, 20 MZ forms were subjected to whole-genome resequencing. Further analysis yielded 3 230 107 high-quality SNPs and uncovered low genetic diversity and high genotype heterozygosity associated with MZ forms' formation. By integrating the SNP data of 427 MZ individuals representing 15 geographic regions, the origins of eight MZ forms were successfully traced using the phylogenetic tree and the identified common heterozygous loci. Meanwhile, transcriptomic analysis was performed using shoots from MZ and its two forms with culm shape variation. The results, combined with genomic analyses, demonstrated that hormone signalling related genes played crucial roles in culm variation. Co-expression network analysis uncovered genes associated with multiple plant hormone signal transduction, especially auxin and cytokinin were involved in culm shape variation. Furthermore, the regulatory relationships of a specific transcription factor and their target genes associated with auxin and ethylene signalling were validated by yeast one-hybrid, electrophoretic mobility shift assays, and dual-luciferase reporter. Overall, this study provides important insights into the culm shape variation formation in bamboo, which facilitates to breed new varieties with novel culms.

The genomes of Darwin's primroses reveal chromosome-scale adaptive introgression and differential permeability of species boundaries.

Introgression is an important source of genetic variation that can determine species adaptation to environmental conditions. Yet, definitive evidence of the genomic and adaptive implications of introgression in nature remains scarce. The widespread hybrid zones of Darwin's primroses (Primula elatior, Primula veris, and Primula vulgaris) provide a unique natural laboratory for studying introgression in flowering plants and the varying permeability of species boundaries. Through analysis of 650 genomes, we provide evidence of an introgressed genomic region likely to confer adaptive advantage in conditions of soil toxicity. We also document unequivocal evidence of chloroplast introgression, an important precursor to species-wide chloroplast capture. Finally, we provide the first evidence that the S-locus supergene, which controls heterostyly in primroses, does not introgress in this clade. Our results contribute novel insights into the adaptive role of introgression and demonstrate the importance of extensive genomic and geographical sampling for illuminating the complex nature of species boundaries.