Search Results (1,251)

The raspberry (Rubus idaeus L.), an economically important crop, is affected by the crumbly fruit disorder, a malformation that leads to fruit disintegration at harvest due to poor drupelet cohesion. Despite previous efforts to identify genetic determinants of this phenotype, its complex inheritance and strong environmental component have limited the development of robust predictive markers. This study assessed the behavior and transferability of previously reported SSR and SNP markers associated with crumbly fruit across plants from a diverse panel of 34 R. idaeus cultivars, including in adjacent genomic regions not screened previously. Phenotyping was based on multi-season fruit performance and drupelet cohesion, and genetic variation was analysed using PCR-based genotyping within a multilocus approach. Consistent clustering patterns were observed across multiple SSR and SNP loci, suggesting a reproducible association between these genomic regions and the crumbly phenotype. Overall, the results support a multilocus genetic architecture underlying crumbly fruit, but also demonstrate that previously reported markers are not universally transferable across genetic backgrounds. These findings highlight the importance of integrated, population-aware marker validation to enable more reliable implementation of marker-assisted strategies in raspberry breeding programs. Full article

Disease resistance breeding is an important direction for the genetic improvement of Chinese cabbage. The traditional elite variety ‘Yutian Baojian’ Chinese cabbage is highly regarded for its tall cylindrical head with a pointed tip, tightly twisted wrapper leaves, and sweet taste. However, long-term cultivation has led to a significant decline in its resistance to clubroot caused by Plasmodiophora brassicae. To restore clubroot resistance while maintaining its desirable horticultural traits, this study used the clubroot-susceptible ‘Yutian Baojian’ as the recurrent parent and the resistant donor ‘Shaocai’, which carries the CRd resistance gene, to develop backcross populations. Using marker-assisted selection (MAS), plants were comprehensively screened based on foreground selection with markers tightly linked to the CRd gene, background selection with 73 genome-wide polymorphic markers, and phenotypic evaluation of horticultural traits, including plant height, plant spread, head shape, and soluble solids content. In the BC₁ population, three individuals showing high genetic similarity were selected. From the BC₂ population, four elite individuals were obtained, exhibiting 99.32% genetic similarity, stable clubroot resistance, and typical horticultural characteristics. Furthermore, three homozygous resistant inbred lines (BC₂S₂) with the ‘Yutian Baojian’ phenotype were developed. These results enrich the clubroot-resistant germplasm resources of Chinese cabbage and provide an effective MAS-based strategy for the precise improvement and germplasm innovation of local cultivars. Full article

Background/Objectives: Downy mildew, caused by Peronosclerospora and Sclerophthora species, is a major constraint to maize production in tropical and subtropical regions, with yield losses of 30–100%. This systematic review synthesised evidence on methods used to screen maize for downy mildew resistance and assessed their effectiveness, reliability, and associated markers. Methods: PubMed, Google Scholar, ScienceDirect, and CAB Abstracts were searched (last searched 22 October 2025) for English-language studies (1990–2025) evaluating phenotypic or molecular screening methods. Risk of bias was assessed using the RoB 2 framework. Narrative synthesis was conducted following a protocol registered on the Open Science Framework. Results: Twelve studies met the inclusion criteria, predominantly from India and Cambodia. Spreader row systems (seven studies) and conidial spray inoculation (six studies) were the most common field methods, while the glasshouse sandwich technique generated the highest disease pressure. Cross-method correlations were strong (r = 0.92–0.99), and heritability estimates ranged from 0.50 to 0.97. QTL mapping identified resistance loci on chromosomes 2, 3, and 6, with chromosome 6 stable across multiple pathogen species. Evidence certainty was moderate for method effectiveness and low for molecular markers. Conclusions: Established phenotypic screening methods reliably discriminate resistant germplasm; however, standardised protocols, broader geographic validation, and independent molecular marker confirmation are needed. Full article

Soybean (Glycine max L. Merr.) is a globally significant oilseed crop. The number of four-seeded pods in the lower part (FSPL) serves as a critical yield component under high-density planting. To date, numerous crop-specific traits have been investigated in multiple breeding studies of soybean; however, little attention has been paid to studies on FSPL. Hence, in this study, we investigated the genetic basis of FSPL using a recombinant inbred line population (RIL3613) across four environments. The segregated genetic mapping population was cultivated during the field experiments, and the collected phenotypic dataset of FSPL exhibited quantitative genetics and high broad-sense heritability (0.724), indicating stable genetic control. Further, we performed quantitative trait locus (QTL) mapping using raw means in each environment and identified 10 QTL, explaining phenotypic variations (PVE) ranging from 0.10% to 2.94%. Among the identified environmentally stable QTL, qFSPL-15-1 was consistently detected across all environments. Two candidate genes [Glyma.15G034100 (encoding lysophosphatidic acid acyltransferase 2) and Glyma.15G034200 (encoding an RNA-binding protein)] were predicted within the flanking genomic interval. The allele frequencies of haplotype combinations of Hap1: Pro2 + CDS1 for Glyma.15G034100 and Hap3: Pro3 + CDS1 for Glyma.15G034200 in wild soybeans (26.6–30.0%) were larger than improved cultivars (52.6–53.4%). We believe that our current findings elucidate the molecular mechanisms regulating lower-pod formation and provide precise genetic targets for marker-assisted selection in high-yield soybean breeding. Full article

Addressing principal challenges in common bean (Phaseolus vulgaris L.) breeding requires a holistic approach. A combined strategy was implemented to assess seven genotypes (landraces and commercial varieties) for yield potential, stability and resistance to bean common mosaic virus (BCMV) under Mediterranean low-input conditions. Pure-line selection and prognostic breeding together with SSR and CAPS-SCAR marker-assisted selection (MAS) formed the core methodology. Significant variation was detected across 24 morpho-agronomic descriptors, while SSR revealed 48.57% polymorphic loci and private alleles in specific landraces. High genetic coefficients of variation and high heritability were recorded for yield-related traits. Phenotypical evaluation showed diverse responses to BCMV, with mild symptoms predominating (52.14%). Entries G1 (45%) and G5 (35%) exhibited the highest frequency of the symptomless resistant phenotype. Molecular screening at I and bc-3/eIF4E loci confirmed G5’s robust dominant I gene profile, while G1 included individuals carrying both the dominant I gene and recessive bc-3, offering a valuable source for pyramiding resistance. Additionally, G1 (LI = 2.35; 100%) performed strongly in productivity, whereas G2 (SI = 3.1; 100%) and G7 (SI = 2.8; 89.7%) exhibited exceptional stability. Overall, the mixed-model approach highlighted the complementary characteristics of the tested genotypes and identified G1, G2, G5 and G7 as promising candidates for future breeding programs targeting high yield, low-input adaptability and resistance to BCMV. Full article

Winter survival in barley depends on freezing tolerance and de-acclimation tolerance, yet their genetic determinants under increasingly unstable winters remain poorly understood. Here, 188 Polish barley accessions were evaluated over two consecutive growing seasons (2021–2022) using genome-wide association studies (GWAS) with a mixed-linear model (MLM) and high-density single nucleotide polymorphism (SNP) and diversity arrays technology sequencing (DArTseq) markers. Freezing and de-acclimation tolerance were quantified by 16 chlorophyll fluorescence parameters and post-freezing survival rates in plants subjected to 21 days of cold acclimation (4 °C/2 °C, day/night) and 7 days of de-acclimation (12 °C/5 °C, day/night). The results showed that freezing and de-acclimation tolerance are related but genetically distinct. The cold-acclimated (CA) state exhibited significant marker–trait associations on chromosomes 2H and 6H, whereas the de-acclimated (DA) state displayed a broader, more complex genetic architecture, particularly on chromosomes 2H and 7H. F_v/F_m showed the strongest associations for both SNP and DArTseq markers in both states. PI_(csm), followed by PI_(cs0) and PI_(total), showed high SNP associations in the DA state, indicating a strong relationship between photosynthetic performance and freezing tolerance after de-acclimation. Notably, the DArTseq marker 11400277 on chromosome 7H showed multiple marker–trait associations across both states. These findings provide a genomic basis for marker-assisted selection of climate-resilient winter barley cultivars. Full article

The common bean (Phaseolus vulgaris L.) cultivar Jalo Vermelho carries the Co-12 gene, which confers resistance to both Andean and Mesoamerican races of Colletotrichum lindemuthianum. Despite its importance for breeding programs, the genomic location and candidate genes underlying this resistance remain poorly defined. The Co-12 locus was fine-mapped using a biparental population derived from the cross Jalo Vermelho × Crioulo 159. A total of 172 F₂ plants were used to generate 172 F_2:3 families, which were phenotyped after inoculation with race 1545 of C. lindemuthianum. Segregation analysis confirmed a 1:2:1 Mendelian ratio, consistent with a single dominant resistance gene. Genotyping of resistant and susceptible plants using the BARBean6K_3 Illumina BeadChip (5398 SNP markers) mapped Co-12 to chromosome Pv04, between 1695 bp (ss715649768) and 9,651,954 bp (ss715646644). Subsequent fine mapping with simple sequence repeat (SSR) markers delimited the locus to a 41 kb genomic interval flanked by BARCPVSSR04557 and BARCPVSSR04570. Within this region, three candidate genes were identified, including one encoding a gamma-glutamyl-GABA enzyme and two encoding lipid transfer proteins (LTP2). Lipid transfer proteins are widely recognized components of plant defense; however, their association with anthracnose resistance in the common bean has not been previously reported. The identification of LTP2 genes within the Co-12 interval suggests a previously unrecognized resistance mechanism and expands the current understanding of host defense pathways in Phaseolus vulgaris. The markers identified here provide valuable tools for marker-assisted selection and will facilitate efficient introgression of Co-12 into common bean cultivars. Full article

Soybean (Glycine max (L.) Merr.) is a globally important legume valued for the high protein, oil, and carbohydrate content of its seeds. However, it is difficult to simultaneously optimize the content of these three macronutrients due to their negatively correlated metabolic pathways and complex quantitative inheritance patterns. In this study, a genome-wide association study (GWAS) was conducted to elucidate the genetic architecture underlying the seed protein, oil, and carbohydrate content in 328 soybean accessions evaluated over two years using near-infrared spectroscopy. Significant negative correlations (r = −0.323 to −0.656, p < 0.001) were observed between the three traits, confirming the trade-off in carbon partitioning during seed development. The GWAS identified nine significant loci distributed across chromosomes 4, 6, 8, 9, 10, 16, and 18 as stable quantitative trait loci (QTLs) regulating the three traits. Of these, three pleiotropic loci (qProOil.4, qProOil.16, and qOilCarb.6) were found to be associated with multiple seed compositional traits. Haplotype analysis revealed seven haplotype blocks with distinct phenotypic variation, indicating that they have the potential for use as trait-specific markers in marker-assisted selection. Functional annotation of the stable QTL regions identified 22 putative genes, among which five candidate genes, Glyma.06g201700, Glyma.08g281900, Glyma.09g164900, Glyma.13g155600, and Glyma.16g209800 were likely to be involved in carbon allocation, protein biosynthesis, lipid metabolism, and carbohydrate modification pathways based on their relative expression levels. Overall, this study enhances the understanding of the genetic and molecular mechanism controlling the composition of soybean seed and identifies promising genomic targets for precision breeding programs aimed at improving nutritional quality. Full article

Broccoli is rich in glucosinolates (GSLs), secondary metabolites that contribute to both plant defense and human health. Optimizing the composition of major aliphatic GSLs is an important breeding objective, yet robust molecular markers for marker-assisted selection (MAS) remain limited. In this study, candidate gene-based kompetitive allele-specific PCR (KASP) markers were developed from conserved GSL biosynthesis genes, focusing on AOP2 and GSL-OH selected from 19 GSL-related genes. Marker–trait associations were evaluated in a natural broccoli population and further validated in an independent F₂ population. Among the tested markers, S101, located in AOP2, exhibited consistent genotype-dependent effects on GNA and PRO across both populations, supporting its stable predictive value. Receiver operating characteristic (ROC) analysis further confirmed strong classification performance of S101 for distinguishing high- and low-content genotypes of these traits in the F₂ population. In contrast, S074 and S035 showed population-dependent effects, with significant associations detected only in the natural population. Although association signals were reduced under mixed linear model (MLM) analysis with false discovery rate (FDR) correction, major loci identified under the general linear model (GLM) framework remained detectable. Overall, these results demonstrate the potential of candidate gene-based KASP markers for improving aliphatic GSL composition in broccoli through marker-assisted selection. Full article

Wheat (Triticum aestivum L.) is one of the most cultivated crops in the world, but production is often affected by drought. The wheat chromosome 4A contains several quantitative trait loci (QTL) associated with drought tolerance and yield-related traits, making it a valuable target for genetic improvement. In this study, we developed near-isogenic lines (NILs) carrying qDT.4A.1, a major QTL for yield using a fast generation cycling system (FGCS) and characterized these NILs for grain yield and thousand-grain weight (TGW) under drought stress and control conditions. We identified a single nucleotide polymorphism (SNP) marker Kukri_c27037_112, which showed a consistent genotype–phenotype associations across two NIL pairs. This marker is linked to four candidate genes encoding a RING-finger E3 ubiquitin ligase, a receptor kinase, and a protein kinase family protein involved in drought stress response and pathways. In silico expression analyses revealed upregulation of these genes in grain tissue under drought conditions, supporting their potential role in grain development and yield formation during drought stress conditions. The identified SNP marker and its associated candidate genes are potential resources in marker-assisted selection and fine mapping pending further validation and functional studies. Our results provide valuable genomic resources, laying the foundation for the development of drought-tolerant wheat varieties and highlighting chromosome 4A as a key region governing drought tolerance. Full article

The Huang-huai sheep (Dorper × Small-tailed Han), certified in China in 2019, initially exhibited issues with genetic uniformity and meat quality. A six-year (2020–2025) breeding program was conducted at two core farms (collectively housing ~2400 breeding ewes representing 12 bloodlines) using the custom “Yuyang Muxin” 10 K SNP chip containing functional markers for reproduction (FecB), growth (CLPG, ACTC1), and meat quality (FABP3, CIDEa). Genotyping and marker-assisted selection were integrated with BLUP breeding values. After six years, favorable FecB genotype frequency increased from 68.97% to 82.58% (p < 0.05), while genetic diversity remained stable (F_IS < 0.05). Mixed model analysis accounting for farm and year random effects revealed significant genetic gains: 6-month ram body weight increased by 9.1% (58.50 to 63.80 kg, p < 0.05), dressing percentage improved from 56.02% to 57.8% (p < 0.05), and loin muscle area expanded by 9.4% (24.50 to 26.8 cm², p < 0.05). Meat quality was enhanced, with shear force decreasing by 14.1% (38.65 to 33.20 N, p < 0.05) and intramuscular fat increasing by 40.0% (2.0% to 2.8%, p < 0.05). Lambs weaned per ewe per year increased from 2.38 to 2.56 (p < 0.05). EBV trend analysis confirmed that improvements were primarily genetic. After Bonferroni correction, CIDEa expression was strongly correlated with intramuscular fat (r = 0.89, p < 0.001) and FABP3 expression with arachidonic acid (r = 0.70, p < 0.001). Nine months was identified as the optimal slaughter age. The “Yuyang Muxin” breeding chip effectively accelerated genetic improvement in Huang-huai sheep, enabling synergistic enhancement of multiple traits. Full article

Rapeseed (Brassica napus L.) faces escalating threats from abiotic and biotic stresses, notably blackleg caused by Leptosphaeria maculans. Due to limited chemical control efficacy and stringent GMO regulations, marker-assisted selection (MAS) leveraging natural genetic variation has become an indispensable strategy for crop improvement. This study identified novel molecular markers for blackleg resistance by integrating genome-wide association study (GWAS) results with high-throughput genotyping by Diversity Arrays Technology sequencing. Phenotypic screening across the population demonstrated a wide spectrum of disease severity (scores 0–6), confirming the segregation of key resistance genes. The DArTseq platform identified nearly 104,000 markers, comprising 61% SilicoDArTs and 39% SNPs. Among the 33 most significant markers associated with resistance (p < 0.01), 76% were SilicoDArTs. Transcriptomic data further validated these findings, revealing 13 marker-linked genes expressed during infection, seven of which exhibited significant differential expression. Comprehensive functional annotation of Arabidopsis thaliana orthologs associated these genes with diverse cellular and plant-wide processes, particularly during stress responses. Collectively, these findings emphasize the complex polygenic nature of blackleg resistance and provide robust genomic tools for the accelerated breeding of resilient B. napus cultivars. Full article

In this study, we investigated the genomic basis of key body measurement and weight traits in Iraqi Awassi sheep using a multi-locus genome-wide association approach. A total of 315 yearling animals were phenotyped for body length, chest depth, heart girth, withers height, and body weight, and genotyped using the Ovine 50K SNP BeadChip. Genome-wide association analyses were performed within the BLUPmrMLM framework to improve the detection of loci with moderate-to-small effects. Significant associations were identified using an LOD-based threshold (LOD ≥ 5), followed by positional annotation of nearby genes and functional enrichment analyses to infer their potential biological relevance. Multiple genomic regions were associated with the evaluated traits. Among the most biologically plausible candidate genes were DST and CFAP299 for body length, ADAMTS8 for chest depth, ZFPM1 and OST4 for heart girth, CPEB2 for body weight, and ITGBL1, RBMS3, and THSD7B for withers height. Functional enrichment analyses indicated the involvement of pathways related to integrin-mediated signaling, focal adhesion and integrin complexes, extracellular matrix organization, and post-transcriptional regulation, suggesting coordinated effects of cell–matrix interactions and gene-expression regulation on body size and conformation. Overall, these findings refine the genomic landscape underlying body weight and morphometric variation in Awassi sheep and provide a focused set of loci for future validation and possible application in marker-assisted and genomic selection programs. Full article

Double-haploid (DH) technology is a well-established method for speeding up the development of inbred lines in breeding programs. The major loci qhir1 and qhir8 are widely used in marker-assisted selection (MAS) to increase the haploid induction rate (HIR) in maize. However, previous studies have shown that HIR can be unstable within populations, even in the presence of these two loci. To identify novel loci associated with HIR, we performed QTL-seq analysis on 337 S₂ haploid inducers (qhir1+/qhir8+) derived from crossing K8 with BHI306. The population exhibited HIR ranging from 0% to 31.16%. We sequence-bulked DNA from 30 extremely high-HIR lines (15.72–31.16%) and 30 extremely low-HIR lines (0–3.84%), identifying candidate intervals on chromosomes 2 (qHI2), 3 (qHI3), 6 (qHI6), and 8 (qHI8). Based on the QTL-seq results, 147 high-confidence SNPs/InDels (R² > 0.3) led to the analysis of 58 genes across three QTLs. We retrieved ten missense mutation SNPs from three genes (GRMZM2G359746 (qHI2), AC198725.4 (qHI3), and GRMZM2G091276 (qHI8)), which are located on chromosomes 2, 3, and 8. Regression analysis of these SNPs showed an R² range of 0.27 to 0.72. The two most highly associated SNPs were located in exon 2 of GRMZM2G359746 (qHI2) and in exon 5 of GRMZM2G091276 (qHI8), respectively. Marker–trait association analysis revealed that lines carrying favorable alleles at both loci, together with qhir1+ and qhir8+, exhibited significantly higher average HIR (12.77%) compared to those with unfavorable alleles (6.66%). These findings provide valuable markers for enhancing maternal haploid inducer breeding programs in maize. Full article

Pepper (Capsicum annuum L.) is a significant vegetable crop, and its fruits tend to accumulate cadmium (Cd). The background value of soil Cd in the main pepper-producing area (southwest China) is relatively high, which results in a high risk of Cd contamination in pepper and its products in this area. Therefore, the cultivation of pepper varieties with low Cd accumulation is vital for ensuring food safety and the development of the pepper industry. A prior genome-wide association study (GWAS) identified the heavy-metal-transporting ATPase gene (CaHMA1) as a crucial gene that facilitates Cd accumulation in pepper fruits. Herein, three semi-thermal asymmetric reverse PCR (STARP) molecular markers (STARP1, STARP2, and STARP3) were designed according to three single-nucleotide polymorphism (SNP) loci (Chr02_154361710, Chr02_154362005, and Chr02_154367255) identified in the intronic region of CaHMA1. Subsequently, these STARP molecular markers were validated using 70 pepper core germplasms with known genotypes. The results indicated that the STARP markers exhibited an identity of over 95% with the corresponding SNP markers. By utilizing the aforementioned STARP markers, the pepper population was divided into two haplotypes (Hap) (Hap1 and Hap2). Under Cd stress, the average Cd content in the fruits of Hap2 pepper was 27.01% lower than that of Hap1. Collectively, these three STARP markers can rapidly and accurately identify the Cd accumulation capacity of pepper varieties with different haplotypes. Furthermore, 24 SNPs were additionally screened from 150 core SNPs according to the criteria of minor allele frequency (MAF) > 0.40, polymorphism information content (PIC) > 0.35, observed heterozygosity (OH) < 0.6, and uniform distribution across 12 chromosomes. These 24 SNPs were combined with the 3 SNPs from the STARP marker developed in the intron region of CaHMA1, and a pepper DNA fingerprinting map was successfully constructed. This DNA fingerprinting map achieved a 100% identification efficiency for 216 pepper germplasm accessions and was able to distinguish the Cd accumulation capacities among different pepper germplasm accessions. In conclusion, this study provides reliable STARP markers for the marker-assisted selection (MAS) breeding of pepper varieties with low Cd accumulation. Moreover, the constructed DNA fingerprinting map possesses dual functions, identifying varieties and evaluating Cd accumulation traits that have high practical value in pepper breeding. Full article