Search Results (103)

Pumpkin (Cucurbita spp.) is a globally significant vegetable crop known for its high nutritional value and remarkable phenotypic diversity. Yet, the surge in new cultivar releases has overwhelmed traditional morphological descriptors, creating critical gaps in variety purity control and breeders’ rights enforcement. Despite the established utility of SNP markers as the gold standard for genetic analysis, a dedicated high-resolution molecular database for modern pumpkin cultivars remains unavailable. To address this gap, we conducted whole-genome resequencing (WGS) on 94 representative pumpkin cultivars (spanning C. moschata, C. maxima, and C. pepo). Clean reads were mapped to the Cucurbita maxima reference genome. We employed a stringent pipeline to identify genomic variants and utilized STRUCTURE software, Principal Component Analysis (PCA), and Neighbor-Joining (NJ) trees to evaluate population stratification. Linkage disequilibrium (LD) decay and DNA fingerprinting barcodes were also developed. A total of 8,873,150 high-quality variants were identified, including 7,345,007 SNPs and 1,528,143 InDels, with an average SNP density of 21,281.50 SNPs/Mb. Population analysis consistently categorized the 94 cultivars into two primary subpopulations (G1 and G2). The first two PCs accounted for 74.06% of the total genetic variance. Further analysis revealed that G1 possessed a more complex genetic architecture and slower LD decay compared to G2, suggesting distinct selection histories. Finally, we screened for highly informative biallelic SNPs to construct a DNA fingerprinting database, enabling precise sample discrimination through unique chromatic barcodes. This study fills a critical gap in pumpkin genomics by establishing a high-density SNP database and a robust fingerprinting system. These resources provide a definitive tool for variety certification, seed purity testing, and the advancement of molecular-assisted breeding in pumpkin. Full article

As a high-value horticultural crop, melon cultivation requires substantial labor input for plant architecture management. Dwarf architecture is a desirable trait for melon breeding, as it simplifies plant management and enables higher planting density. In this study, we identified a spontaneous dwarf mutant, HMN-d, derived from a cantalupensis melon HMN. Compared to HMN, HMN-d exhibited a 70% reduction in plant height with unchanged node number. BSA-seq mapped the mutation to a single 1.86 Mb interval on chromosome 7 containing CmER, a known regulator of melon height. A novel loss-of-function allele, Cmer-2, introducing a premature stop codon, was identified in this region of HMN-d. Linkage analysis using 1455 F₂ individuals via KASP marker developed from the Cmer-2 variant revealed complete co-segregation with the dwarf phenotype. Allelism analysis further demonstrated that Cmer-2 is allelic to Cmer-1, a previously identified loss-of-function allele of CmER. CmER knockout lines generated by gene editing recapitulated the dwarf phenotype, directly confirming that loss of CmER function is sufficient to cause dwarfism. Collectively, these findings establish Cmer-2 as the causal variant underlying the dwarf phenotype and provide valuable genetic resources for melon plant architecture improvement and for dissecting the mechanisms of height regulation. Full article

Sweetpotato (Ipomoea batatas (L.) Lam.) is an important multifunctional crop with great value in food supply, industrial processing and bioenergy utilization. Crude protein content (CPC) is a core target trait for sweetpotato quality breeding. To dissect the genetic basis of CPC and identify key candidate genes, we used an F₁ population of 212 individuals. CPC was measured by near-infrared reflectance spectroscopy (NIRS) in 2020 and 2021, and QTL mapping was performed using a high-density SNP genetic linkage map. Candidate genes were explored via a genome-wide association study (GWAS), multiple-database functional annotation, and quantitative real-time PCR (qPCR) validation. The results showed that: (1) CPC in the population exhibited a continuous normal distribution with high inter-year stability, and phenotypic variation was mainly controlled by genetic factors; (2) one stable minor-effect QTL for CPC, qCPC09-1, was mapped to Chr09: 7906895–8614924 bp, explaining 5.7% of phenotypic variation; (3) GWAS detected no significant SNP loci, suggesting that CPC is regulated by multiple minor-effect genes; (4) genes within the qCPC09-1 interval were significantly enriched in three protein synthesis-related KEGG pathways: ribosome, nitrogen metabolism and ubiquinone and other terpenoid–quinone biosynthesis; (5) qPCR verified that itf09g13420 and itf09g13230 were upregulated in the low-CPC parent Yushu 10 and negatively correlated with CPC, while itf09g13550 was upregulated in the high-CPC parent Xin 24 and positively correlated with CPC. These three genes exhibited expression patterns highly consistent with phenotypic differences. This study provides a theoretical basis and technical support for molecular marker-assisted breeding and elite germplasm innovation in sweetpotato. Full article

Bougainvillea (Bougainvillea glabra) is a perennial woody species belonging to the Nyctaginaceae family, native to South America. It is widely recognized for its brightly colored bracts and strong adaptability, and is widely cultivated as a major ornamental plant in tropical and subtropical regions. However, QTL mapping studies on morphological traits remain limited in the genus Bougainvillea, and the genetic basis underlying its key ornamental traits is still largely unclear. In this study, an F₁ segregating population was constructed using the cultivars ‘Mrs Eva White’ and ‘Formosa’ as parents, and was used for high-density genetic map construction and quantitative trait locus analysis. Fourteen leaf and thorn-related traits were investigated, with coefficients of variation ranging from 8.16% to 64.54%. Based on specific-locus amplified fragment sequencing (SLAF-seq), a total of 1,133,206 SLAF markers were developed, among which 479,488 were polymorphic. Using the inclusive composite interval mapping (ICIM) algorithm in the GACD 1.2 software, a high-density genetic linkage map was constructed for B. glabra, consisting of 17 linkage groups and 3256 markers. The genetic map spanned 1797.64 cM, with an average marker interval of 0.55 cM. A total of 22 QTLs were detected for the measured leaf and thorn traits, including 16 major QTLs with a PVE ≥ 8%. Collectively, this study identified stable genetic loci for important morphological traits and provides a valuable theoretical foundation for marker-assisted selection and genetic improvement of ornamental traits in Bougainvillea. Full article

Plant architecture is a critical agronomic trait in watermelon (Citrullus lanatus), with vine length directly influencing planting density, light interception, and field management efficiency. Short-vine forms have become important agronomic targets in breeding due to their advantages of high-density planting, efficient light utilization, and simplified field management. In this study, a dwarf mutant, designated PKH207, was identified from an ethyl methanesulfonate (EMS)-mutagenized population of the watermelon inbred line G42. The mutant exhibited significantly reduced plant height and shortened internodes due to decreased cell expansion in stem tissues. Genetic analysis indicated that the dwarf phenotype in PKH207 is controlled by a single recessive gene, which was named Cldw2 (Citrullus lanatus dwarf mutant 2). Using a population of 558 F₂ plants, bulked segregant analysis sequencing (BSA-seq) and linkage mapping delimited the causal locus to a 540.6 kb region on chromosome 10. Within this interval, a single-nucleotide polymorphism (SNP) mutation was identified in the gene ClG42_10g0100600, encoding an α-tubulin, and this gene was determined to be the candidate gene for the dwarf phenotype. Transcriptome analysis revealed that this mutation significantly disrupts key biological processes, including cell wall biosynthesis, microtubule cytoskeleton organization, and auxin signaling pathways, contributing to the dwarfism phenotype. This study identifies a novel dwarfing allele in cucurbits and provides a direct molecular target for breeding compact watermelon cultivars suited to high-density production. Full article

Rapid Visco Analyzer (RVA) profile characteristics are important indicators of rice (Oryza sativa L.) eating quality. In this study, based on the high-density genetic linkage map constructed under the genetic background of Yuexianghzan (YXZ) and Shengbasimiao (SBSM), combined with the RVA profile characteristic data of recombinant inbred lines (RILs) grown in two environments, QTL scanning was performed using the ridge regression analysis method. A total of 59 QTLs associated with RVA profile characteristics were detected across 11 chromosomes in the two environments, with individual QTLs explaining 0.12% to 85.16% of the phenotypic variation. Moreover, 11 QTLs were repeatedly detected in two environments with large effects. The QTL located in the 1.44–1.85 Mb interval on chromosome 6 simultaneously controlled eight RVA profile characteristics and contained the cloned waxy (Wx) gene. Additionally, the intervals 20.58–20.70 Mb on chromosome 5 and 24.96–25.42 Mb on chromosome 8 were repeatedly mapped and influenced multiple RVA characteristics. Based on gene annotation information, a total of nine candidate genes (LOC_Os05g34730, LOC_Os05g34830, LOC_Os05g34854, LOC_Os06g03910, LOC_Os06g04200, LOC_Os06g42720, LOC_Os08g39830, LOC_Os08g39850, and LOC_Os08g39860) that directly or indirectly influence the starch synthesis pathway were identified. The results of this study lay a foundation for further map-based cloning of genes related to rice RVA profile characteristics and molecular design breeding. Full article

The large yellow croaker (Larimichthys crocea) is a key mariculture species in China, however, its industry is threatened by visceral white nodules disease (VWND) caused by the bacterium Pseudomonas plecoglossicida. A significant challenge in breeding is the potential genetic trade-off between growth and disease resistance. To investigate their genetic relationship, we constructed a high-density SNP-based genetic linkage map for L. crocea using a F1 full-sib family (n = 150). The map comprised 24 linkage groups with 32,429 bin markers and an average interval of 0.051 cM. Based on this map, we conducted QTL mapping for one yield trait (body weight), eight morphological traits, and three VWND-resistance traits (survival time, AT; spleen and liver pathogen loads). Phenotypic analysis revealed strong integration among growth traits and a moderate positive correlation between growth traits and AT. QTL mapping identified 53 QTLs for growth (PVE = 0.14–5.83%) and 20 for resistance (PVE = 0.78–8.93%). Notably, only two genomic intervals exhibited co-localization between a morphological trait (AL or BL) and AT, each explaining a modest phenotypic variance (0.66–5.99%). The largest-effect QTLs for growth and resistance were mapped to distinct linkage groups, and candidate genes within the co-localized intervals (Unc5d, SCN5A, HUS1) are involved in fundamental cellular processes rather than core growth or immune pathways. These results suggest that yield, morphological, and VWND-resistance traits in L. crocea are largely under independent genetic control within the studied family, indicating that simultaneous improvement of growth and disease resistance is feasible. This study provides a molecular basis for breeding strategies aimed at overcoming the trait trade-off bottleneck in this economically vital species. Full article

While striped catfish (Pangasianodon hypophthalmus) is an economically important aquaculture species, its genomic resources remain limited. To date, linkage maps, QTL (quantitative trait loci) analyses, and the identification of candidate genes associated with disease resistance traits are very limited. Therefore, the present study aimed to construct a high-density linkage map and identify candidate genes for this species. Our analysis was conducted on a pedigree population consisting of 560 individuals (490 offspring and 70 parents for 40 families), whose genomes were analyzed using a genotyping-by-sequencing platform. After stringent filtering, 9882 high-quality SNPs were retained for linkage analysis. Linkage analysis placed 8786 markers onto 30 linkage groups (LGs), with an average density of 0.43 SNPs per cM. Recombination rates varied across the 30 linkage groups (LGs), averaging of 3.6 cM/Mb in males, 6.7 cM/Mb in females, and 5.1 cM/Mb when sex-averaged. Using the linkage map, our QTL analysis identified three significant QTLs for disease resistance to Edwardsiella ictaluri, the causative agent of Bacillary Necrosis of Pangasius (BNP). The QTLs were located on LG1, LG9 and LG29, and their peak markers explained 17.03% of the phenotypic variance. An LD-based interval of approximately ±25 kb surrounding the QTL peak was identified as the putative candidate region. However, subsequent genome-wide association analysis did not identify significant SNP effects within these regions, suggesting that the QTLs may represent polygenic or small-effect loci that are detectable only in linkage-based analyses. In summary, this study presents the first high-density SNP-based linkage map for striped catfish and reports significant QTL and associated candidate genes related to disease resistance and growth traits. These findings provide valuable insights into the genetic architecture of economically important traits in P. hypophthalmus. Nevertheless, further validation in independent populations is required before incorporating these markers into selective breeding programs. Full article

Sweet corn is widely cultivated and valued for its palatability and nutritional quality, with kernels accumulating substantial carotenoids, which serve as essential antioxidants and vitamin A precursors. This study elucidated the genetic basis of carotenoid variation in sweet corn kernels by integrating quantitative trait loci (QTL) mapping with a candidate region association study. Seven carotenoid-related traits were quantified in a recombinant inbred line (RIL) population and its parental lines. QTL mapping based on a high-density genotyping-by-target sequencing (GBTS) map and BLUE values across two environments identified 15 loci on chromosomes 5, 6, 7, 8, and 9, explaining 3.83–17.25% of the phenotypic variance. Notably, chromosome 6 harbored a cluster of major-effect QTLs regulating β-cryptoxanthin, zeaxanthin, lutein, total carotenoids, and provitamin A contents. A regional association study within these linkage-defined intervals detected 71 significant SNPs (Bonferroni p < 1/n) and identified Zm00001d036238, encoding a GDSL esterase/lipase, as a strong candidate gene associated with β-cryptoxanthin accumulation. This gene exhibited kernel-specific expression in the endosperm and harbored a downstream cis-variant (Chr6: 78,466,427) correlated with increased carotenoid content. Allelic effect analysis indicated that the A/A genotype conferred markedly higher β-cryptoxanthin levels than other genotypes. Collectively, these findings provide valuable genetic resources for marker-assisted selection and biofortification breeding to enhance the nutritional quality of sweet corn. Full article

Helianthus annuus L. is one of the major oilseed crops worldwide, and its production is seriously affected by a highly destructive necrotrophic pathogen, Sclerotinia sclerotiorum (S. sclerotiorum). The use of resistant cultivars is the best control measure via molecular breeding; however, the gene action underlying resistance to this stress is not well-established. Here, we conducted QTL analysis for S. sclerotiorum resistance in a recombinant inbred line (RIL) population that were developed from parents with resistant (C6) and susceptible (B728) to the disease. A high-density genetic linkage map with 6059 single nucleotide polymorphism (SNP) markers and a total length of 2763 cM was developed. The lesion length (LL) and the lesion area (LA) in the field, under climate chamber conditions or greenhouse conditions, were assessed following standardized inoculation protocols. A total of 16 major QTL for LL and 12 for LA were detected across three experimental environments, explaining 1.58–32.86% of the phenotypic variation. Of these, a major-effect QTL, qSCL2.4 on chromosome 2, could explain 30.22% of phenotypic variance with alleles from parent C6 which had more increased resistance to S. sclerotiorum. Fine-mapping in the BC₁F₃ population narrowed the locus to a 226.7 kb interval. HaWRKY48, which encodes a WRKY transcription factor located in this region, was prioritized as the prime candidate gene. Polymorphism analysis of HaWRKY48 in 138 sunflower accessions revealed eight SNPs defining six haplotypes. Resistance was associated with Hap3 and susceptibility to Hap1/Hap6. These findings advance our understanding of the genetic mechanisms governing sunflower resistance to S. sclerotiorum and provide valuable genetic markers for molecular breeding of resistant cultivars. Full article

A genetic linkage map of Grifola albicans f. huishuhua (Maitake) is an important resource for chromosome analysis and the genetic basis of phenotypic variation determination. A total of 92 monokaryotic isolates were selected from the F1 generation of Q3-8 × Y1-18 in this study. Restriction site-associated DNA sequencing, as well as identification of single nucleotide polymorphisms (SNPs), was performed, aiming to illustrate a high-density genetic linkage map. A total of 1122 high-quality SNP markers were located on a map with a length of 1473.60 centimorgan (cM) by screening 589534 SNPs. This map covers 12 linkage groups (LGs) with an average genetic distance of 122.80 cM. Three quantitative trait loci (QTLs) related to the growth rate of G. albicans f. huishuhua strains were identified using the composite interval mapping method. These QTLs were mapped to linkage groups (LGs) as follows: LG3 (qmgv), LG4 (qmb), LG5 (qmd), LG8 (qrdm1, qrdm2), and LG10 (qmgrc1, qmgrc2, qmgrc3). The genes associated with mycelial growth rate and biomass production of these strains were identified. This information could be used for molecular marker-assisted selective breeding in G. albicans f. huishuhua. Full article

Spinach is a beloved vegetable crop and widely cultivated worldwide. It is dioecious with male and female plants, although monoecious mutations exist. Female spinach exhibits two distinct sepal morphologies—thorn-shaped and round-shaped determine seed shape and strongly influence seed handling, mechanized sowing, and cultivar classification. To dissect the genetic basis of this trait, we developed an F₂ population from contrasting parental lines and constructed a high-density linkage map with ~1615 bin markers spanning ~994.04 cm. A major 4.31 Mb genomic interval on chromosome 4, flanked by tightly linked markers, was consistently associated with sepal morphology. Transcriptome profiling across early and mature sepal developmental stages revealed significant enrichment of cell cycle-related pathways, including DNA replication, repair, mitosis, and cytokinesis. By integrating differential expression analysis with weighted gene co-expression network analysis, we identified 25 DEGs within the mapped interval, 11 of which showed strong co-expression with hub genes in trait-associated modules. Structural variation analysis further uncovered promoter and coding sequence polymorphisms in a subset of candidate genes. This study highlights 11 promising candidate genes potentially regulating sepal-derived seed morphology in spinach, rather than confirming definitive causal genes, providing valuable targets for functional validation and new insights into the genetic regulation of sepal development. Full article

Kernel row number (KRN) is a pivotal determinant for yield in maize breeding programs. However, the genetic basis underlying KRN remains largely elusive. To identify candidate genes regulating KRN, a population of 318 BC₄F₄ chromosomal segment substitution lines (CSSLs) was developed via backcrossing, with Baimaya (BMY) as the donor parent and B73 as the recurrent parent. Furthermore, a high-density genetic linkage map containing 2859 high-quality single-nucleotide polymorphism (SNP) markers was constructed for quantitative trait locus (QTL) mapping of KRN. Notably, 19 QTLs controlling KRN were detected across three environments and in the Best Linear Unbiased Prediction (BLUP) values; among these, a major-effect QTL (qKRN4.09-1) was consistently identified across all three environments and BLUP. Then, the integration of linkage mapping and transcriptome analysis of 5 mm immature ears from near-isogenic lines (NILs) uncovered a candidate gene, Zm00001eb205550. This gene exhibited significant downregulation in qKRN4.09-1^BMY, and two missense variants were detected between qKRN4.09-1^BMY and qKRN4.09-1^B73. Zm00001eb205550 exhibited preferential expression in developing ears. Moreover, the pyramiding of favorable alleles from the five stable QTLs significantly increased KRN in maize. These findings advance our genetic understanding of maize ear development and provide valuable genetic targets for improving KRN in maize breeding. Full article

Yellow rust (YR), caused by Puccinia striiformis f. sp. tritici (Pst), is a global disease infecting wheat that seriously affects the yield and the quality of grains. Wheat breeding line C855 is immune to the mixed Pst isolates CYR32 + CYR33 + CYR34 under field conditions. To identify the Yr-loci carried by C855, in this study, an F₂ population derived from the crossing of C855 with Yannong 999, a YR-sensitive cultivar, was established, and the infection type (IT) of each F₂ individual was estimated. The correlation analysis results show that YR resistance was significantly positively correlated with grain weight and grain size. Using a 120K single-nucleotide polymorphism (SNP) array, the F₂ population was genotyped, and a high-density genetic map covering 21 wheat chromosomes and consisting of 5362 SNP markers was built. Then, five Yr-QTLs on chromosomes 1B, 2A, 2B, and 2D were identified. Of these, the QTL on chromosome 2A, temporarily named QYr.sxau-2A.1, is a major-effect QTL explaining 15.62% of the phenotypic variance. One PCR-based marker SSR2A-14 for QYr.sxau-2A.1 was developed, and the C855 allele of SSR2A-14 corresponded to the stronger Yr resistance. QYr.sxau-2A.1, located in the 228.02~241.58 Mbp physical interval, is different from all the known Yr loci on chromosomes 2A. Within the interval, there are 30 annotated genes, including a nucleotide-binding site and a leucine-rich repeat (NBS-LRR)-encoding gene with the linkage marker NRM2A-16 of QYr.sxau-2A.1. Our results reveal a novel major-effect QYr.sxau-2A.1, which provided resistance to YR and is a molecular marker for wheat breeding. Full article

Background/Objectives: The Chinese dwarf cherry (Cerasus humilis) is an endemic shrub fruit tree species in China. Its fruit is flavorful, nutrient-rich, and has considerable research and utilization potential. However, most currently cultivated varieties of C. humilis are highly acidic and primarily used for processing. Consumer-preferred, low-acid, fresh-eating varieties are scarce, limiting industrial development. We used 208 F₁ individuals derived from a cross between high-acid “Nongda 4” and the low-acid “DS-1”. Methods: Restriction site-associated DNA sequencing (RAD-seq) was used to develop single-nucleotide polymorphism (SNP) markers and construct a high-density genetic linkage map. Using two years of fruit titratable acidity phenotypic data, quantitative trait locus (QTL) mapping and candidate gene screening were performed. Results: The genetic map contained 2491 SNP markers, assigned to eight linkage groups. The total genetic distance was 672.71 cm, with an average distance of 0.27 cm between markers, indicating high map quality. QTL mapping identified 18 loci associated with fruit titratable acidity, including 11 major-effect QTLs (logarithm of odds, LOD ≥ 3.5). These major-effect QTLs were concentrated on linkage groups LG2 and LG5, with an explained phenotypic variation of 8.6–31.13%. Two candidate genes were identified within QTL intervals: phosphoester phosphatase and MATE transmembrane transporter. The phosphatase gene’s expression showed a strong correlation with titratable acid content (p < 0.01, correlation coefficient 0.93), suggesting that it plays an important role regulating fruit acidity in C. humilis. Conclusions: This study supports marker-assisted breeding of low-acid, fresh-eating varieties, aiding commercial promotion of C. humilis. Full article