Molecular Marker-assisted Selection Research Articles

Importance of OsRac1 in Signalling of Pigm-1 Mediated Resistance to Rice Blast Disease

In rice, leucine-rich repeat nucleotide-binding site (NLR) proteins are pivotal immune receptors in combating Magnaporthe oryzae-triggered rice blast. However, the precise molecular mechanism underlying how NLR proteins regulate downstream signalling remains elusive due to the lack of knowledge regarding their direct downstream targets. The NLR protein Pigm-1 was cloned from Shuangkang 77009 in our laboratory. This study shows that the nucleotide-binding site (NBS) domain of Pigm-1 facilitates its binding to and activation of OsRac1 while the coiled-coil (CC) domain enables its binding to and activation of RAI1, ultimately inducing cell death. At the same time, after knocking out OsRac1 in the background of Shuangkang 77009 containing Pigm-1, two knockout lines showed susceptibility to rice blast. This study reveals OsRac1, a GTPase, as a signalling molecule involved in Pigm-1-mediated blast resistance, suggesting its potential as a common downstream effector of rice NLR proteins. Additionally, a transcriptional activator, RAI1, acts as an essential Pigm-1 interactor for blast resistance. Furthermore, a novel material 9311(Pigm-1) was prepared by using two-line restorer line 9311 as receptor and Shuangkang 77009 as donor with molecular marker-assisted technology, which improved blast resistance and yield. This research demonstrates that molecular marker-assisted selection technology enhances both resistance and yield in the crucial two-line restorer 9311(Pigm-1). This study offers crucial insights into how Pigm-1 protein activates downstream molecules and serves as a valuable reference for the molecular breeding of rice blast resistance genes, particularly Pigm-1.

Improving panicle blast resistance and fragrance in a high-quality japonica rice variety through breeding

IntroductionHuruan1212 (HR1212) is well-regarded for its superior eating and cooking quality in the lower reaches of the Yangtze River in China. Still, its high susceptibility to rice panicle blast and lack of fragrance have limited its further spread and utilization. Pigm and Pi-ta are two dominant genes known for their stable broad-spectrum resistance against rice blast fungus Magnaporthe oryzae, while badh2 is the crucial gene that regulates rice aroma.MethodsIn this study, we utilized a molecular marker-assisted selection backcrossing strategy to introduce Pigm, Pi-ta, and badh2 into introgressed lines employing re-sequencing for precise genetic background selection.ResultsFinally, we selected three introgressed lines, including two that carry Pigm with the highest background recovery rates, showing eating and cooking qualities similar to those of HR1212, and one line that pyramids Pigm, Pi-ta, and badh2, which features a strong aroma. They all displayed significantly enhanced resistance to panicle blast and improved yield compared to HR1212.DiscussionIn conclusion, this study expanded the germplasm resources of japonica, providing a material foundation for enhancing breeding programs aimed at developing rice blast-resistant and high-quality fragrant japonica varieties. Additionally, the study demonstrated that integrating molecular markers and re-sequencing can inform breeders’ decision-making more precisely and efficiently.

Genome-Wide Association Analysis of Growth Traits in Hu Sheep.

(1) Background: The Hu sheep is a renowned breed characterized by high reproduction, year-round estrus, and resistance to high humidity and temperature conditions. However, the breed exhibits lower growth rates and meat yields, which necessitate improvements through selective breeding. The integration of molecular markers in sheep breeding programs has the potential to enhance growth performance, reduce breeding cycles, and increase meat production. Currently, the applications of SNP chips for genotyping in conjunction with genome-wide association studies (GWAS) have become a prevalent approach for identifying candidate genes associated with economically significant traits in livestock. (2) Methods: To pinpoint candidate genes influencing growth traits in Hu sheep, we recorded the birth weight, weaning weight, and weights at 3, 4, 5, 6, and 7 months for a total of 567 Hu sheep, and genotyping was performed using the Ovine 40K SNP chip. (3) Results: Through GWAS analysis and KEGG pathway enrichment, we identified three candidate genes associated with birth weight (CAMK2B, CACNA2D1, and CACNA1C). Additionally, we found two candidate genes linked to weaning weight (FGF9 and BMPR1B), with CACNA2D1 also serving as a shared gene between birth weight and weaning weight traits. Furthermore, we identified eight candidate genes related to monthly weight (FIGF, WT1, KCNIP4, JAK2, WWP1, PLCL1, GPRIN3, and CCSER1). (4) Conclusion: Our findings revealed a total of 13 candidate genetic markers that can be utilized for molecular marker-assisted selection, aiming to improve meat production in sheep breeding programs.

Genetic Linkage Map Construction and QTL Mapping for Juvenile Leaf and Growth Traits in Camellia oleifera

Advancement of the oil tea industry requires the development of high-yielding and superior-quality varieties of Camellia oleifera, a major oilseed crop. However, traditional breeding methods, hampered by lengthy cycles and low selection accuracy, significantly constrain the breeding process. Identifying single nucleotide polymorphisms (SNPs) associated with target traits, and applying molecular marker-assisted selection (MAS) for these traits, can thereby shorten the breeding cycles and amplify the breeding efficiency. In this study, we utilized the hexaploid C. oleifera as the reference genome to identify high-quality SNPs and constructed a high-density genetic linkage map of C. oleifera that spanned 1566.733 cM, included 3097 SNPs, and was anchored to 15 linkage groups. Using interval mapping, we localized quantitative trait loci (QTLs) for 11 juvenile traits in C. oleifera, identifying 15 QTLs for growth traits and 24 QTLs for leaf traits, including 4 stable QTLs. The logarithm of odds (LOD) scores for individual QTLs ranged from 3.48 to 14.62, explaining 9.86–48.61% of the phenotypic variance. We further identified 2 SNPs associated with growth traits (marker11-951 and marker12-68) and 10 SNPs associated with leaf traits (marker11-276, marker11-410, marker11-560, marker13-16, marker13-39, marker13-110, marker13-731, marker14-701, marker14-910, and marker14-1331). These results provide valuable insights into the genetic mapping of key traits in C. oleifera and will contribute to the development of new varieties with high yield and superior quality in the future.

Insight into Rice Resistance to the Brown Planthopper: Gene Cloning, Functional Analysis, and Breeding Applications.

This review provides a comprehensive overview of the current understanding of rice resistance to the brown planthopper (BPH), a major pest that poses significant threats to rice production through direct feeding damage and by transmitting viruses such as Rice grassy stunt virus (RGSV) and Rice ragged stunt virus (RRSV). We highlight the emergence of various BPH biotypes that have overcome specific resistance genes in rice. Advances in genetic mapping and cloning have identified 17 BPH resistance genes, classified into typical R genes encoding nucleotide-binding leucine-rich repeat (NLR) proteins and atypical R genes such as lectin receptor kinases and proteins affecting cell wall composition. The molecular mechanisms of these genes involve the activation of plant defense pathways mediated by phytohormones like jasmonic acid (JA), salicylic acid (SA), and ethylene, as well as the production of defensive metabolites. We also examine the complex interactions between BPH salivary proteins and rice defense responses, noting how salivary effectors can both suppress and trigger plant immunity. The development and improvement of BPH-resistant rice varieties through conventional breeding and molecular marker-assisted selection are discussed, including strategies like gene pyramiding to enhance resistance durability. Finally, we outline the challenges and future directions in breeding for durable BPH resistance, emphasizing the need for continued research on resistance mechanisms and the development of rice varieties with broad-spectrum and long-lasting resistance.

Development and Validation of Kompetitive Allele-Specific Polymerase Chain Reaction Markers for Seed Protein Content in Soybean.

Seed protein content is a critical trait in soybean breeding, as it provides a primary source of high-quality protein for both human consumption and animal feed. This study aimed to enhance molecular marker-assisted selection for high-protein soybean varieties by developing Kompetitive Allele-Specific Polymerase Chain Reaction (KASP) markers targeted at loci associated with seed protein content. Nineteen markers with high genotyping efficacy were identified through screening. Utilizing SN76 (a high-protein line) as the male parent and SN49 and DS1 (both low-protein lines) as female parents, 484 F6 generation individuals from these hybrid combinations were selected to validate the predictive accuracy of the 19 KASP markers. Notably, KASP-Pro-1, KASP-Pro-2, and KASP-Pro-3 effectively distinguished genotypes associated with high and low protein content, with prediction accuracies of 68.4%, 75.0%, and 83.3%, respectively. These results underscore the reliability and practical utility of the selected molecular markers, which are located within the genes Glyma.03G219900, Glyma.14G119000, and Glyma.17G074400, respectively. Haplotype analysis and gene pyramiding indicate that these three genes may influence seed protein content. Consequently, these KASP markers can be effectively integrated into genetic and genomic research on soybean seed protein content as well as into marker-assisted breeding.

Genetic dissection of flour whiteness through genome-wide association analysis in common wheat (Triticum aestivum L.)

The color of flour products has an important influence on consumer acceptance. Flour color is largely determined and measured by the index of flour whiteness (FW) in China. In this study, an association population comprising 207 wheat (Triticum aestivum) accessions originating from seven countries was used for dissection of FW-related genetic loci through genome-wide association analysis. Six quantitative trait loci (QTLs) significantly associated with FW were identified, accounting for 7.87%–16.53% of the total phenotypic variation. Four KASP markers were developed from single-nucleotide polymorphisms associated with the QTLs QFW.HAAS-1AS, QFW.HAAS-1BL, QFW.HAAS-5AL, and QFW.HAAS-7AL. The phytoene synthase-encoding gene TraesCS7A03G1357000 (TaPsyA1) was identified as a candidate gene for QFW.HAAS-7AL. Two allelic variants of TaPsyA1 (designated PsyA1-a and PsyA1-b) were differentiated on the basis of a 37bp insertion/deletion polymorphism in the second intron. PsyA1-b included the 37bp insertion, which led to a translational frameshift in the gene and was associated with higher FW. The PsyA1-a allele lacked the 37bp insertion and was classified into two haplotypes according to the number of repeated ‘TC’ units in a simple sequence repeat in the promoter region. Of the two PsyA1-a haplotypes, the Type 1 haplotype conferred higher FW, flour brightness, and flour redness, and lower yellow pigment content and flour yellowness. The KASP markers and PsyA1 polymorphic markers developed in the present study are suitable for use in molecular marker-assisted selection for improvement of wheat FW.

Quantitative Trait Loci Mappings for the Sulfur Utilization Efficiency-Related Traits at the Seedling Stage of Wheat.

Sulfur (S) is a vital element for the normal growth and development of plants, performing crucial biological functions in various life processes. This study investigated thirteen S utilization efficiency (SUE)-related traits at the seedling stage of wheat using a recombinant inbred line (RIL) population. The quantitative trait loci (QTLs) were mapped by genetic mapping. Thirteen S utilization efficiency-related traits were investigated under two hydroponic culture trials with low S (0.1S, T1), moderate S (0.5S, T2), and high S (1.5S, T3) levels, using the wheat RILs. A total of 170 QTLs for the thirteen traits in different treatment environments were identified. Among them, 89, 103, and 101 QTLs were found in T1, T2, and T3, respectively. A total of 63 QTLs were found in the multiple treatment environments, the other 107 QTLs only being detected in a single treatment environment. Among them, thirteen relatively high-frequency QTLs (RHF-QTLs) and eleven QTL clusters were found. Five (QSh-1D, QRn-1D, QSdw-1D, QTdw-1D, and QTsc-1D) and six (QRdw-6A, QSdw-6A, QTdw-6A, QRsc-6A, QSsc-6A, and QTsc-6A) RHF-QTLs were identified in QTL clusters C3 and C10, respectively. These thirteen RHF-QTLs and eleven QTL clusters are expected to apply to the molecular marker-assisted selection (MAS) of wheat.

Identification and segregation of two closely linked major QTLs for kernel row number in advanced maize-teosinte populations.

Two closely linked novel loci, qKRN2-1 and qKRN2-2, associated with kernel row number were fine-mapped on chromosome 2, and a key candidate gene for qKRN2-1 was identified through expression analysis. Kernel row number (KRN) is a crucial factor influencing maize yield and serves as a significant target for maize breeding. The use of wild progenitor species can aid in identifying the essential traits for domestication and breeding. In this study, teosinte (MT1) served as the donor parent, the inbred maize line of Mo17 was used as the recurrent parent, we identified a major quantitative trait locus (QTL) for KRN, designated qKRN2, into two closely linked loci, qKRN2-1 and qKRN2-2. Here, fine mapping was performed to investigate two QTLs, qKRN2-1 and qKRN2-2, within a genomic range of 272kb and 775kb, respectively. This was achieved using a progeny test strategy in an advanced backcross population, with the two QTLs explaining 33.49% and 35.30% of the phenotypic variance. Molecular marker-assisted selection resulted in the development of two nearly isogenic lines (NILs), qKRN2-1 and qKRN2-2, which differed only in the segment containing the QTL. Notably, the maize (Mo17) alleles increased the KRN relative to teosinte by approximately 1.4 and 1.2 rows for qKRN2-1 and qKRN2-2, respectively. Zm00001d002989 encodes a cytokinin oxidase/dehydrogenase and its expression in the immature ears exhibited significant differences among the qKRN2-1 NILs. In situ hybridization localized Zm00001d002989 to the primordia of the inflorescence meristem and spikelet pair meristems, is predicted to be the causal gene of qKRN2-1. The findings of this study deepen our understanding of the genetic basis of KRN and hold significant potential for improving maize grain yields.

Molecular Mechanisms of Heterosis and Its Applications in Tree Breeding: Progress and Perspectives.

Heterosis, or hybrid vigor, refers to the phenomenon where hybrid progenies outperform their parents in traits such as yield and resistance. This phenomenon has been widely applied in plant breeding. Recent advances in high-throughput genomics have significantly advanced our understanding of heterosis. This review systematically summarizes the genetic, molecular, and epigenetic mechanisms underlying heterosis. Furthermore, we discuss recent advances in predictive methods for heterosis and their applications in improving growth rate, resistance to abiotic stresses, and wood yield in tree species. We also explore the role of tree genomics in unraveling the mechanisms underlying heterosis, emphasizing the potential of integrating high-resolution genomics, single-cell sequencing, and spatial transcriptomics to achieve a comprehensive understanding of heterosis from the molecular to spatial levels. Building on this, CRISPR-based gene-editing technologies can be employed to precisely edit heterotic loci, enabling the study of allele function. Additionally, molecular marker-assisted selection (MAS) can be utilized to identify heterotic loci in parental lines, facilitating the selection of optimal hybrid combinations and significantly reducing the labor and time costs of hybrid breeding. Finally, we review the utilization of heterosis in tree breeding and provide a forward-looking perspective on future research directions, highlighting the potential of integrating multi-omics approaches and emerging gene-editing tools to revolutionize tree hybrid breeding.

Detection of Candidate Genes and Development of KASP Markers for Pod Length and Pod Width by Combining Genome-Wide Association and Transcriptome Sequencing in Vegetable Soybean

Vegetable soybeans are one of the most important vegetable types in East Asia. The yield of vegetable soybeans is considerably influenced by the size of their pods. To facilitate the understanding of the genetic basis of the pod length and width in vegetable soybeans, we conducted a genome-wide association study (GWAS) and transcriptome sequencing. Four quantitative trait loci, namely, qGPoL1, qGPoL2, qGPoW1, and qGPoW2, were mapped via GWAS analysis. Through the integration of gene function annotation, transcriptome sequencing, and expression pattern analysis, we identified Glyma.06G255000 and Glyma.13G007000 as the key determinants of the pod length and width in vegetable soybeans, respectively. Furthermore, two kompetitive allele-specific polymerase chain reaction (KASP) markers, namely, S06-42138365 (A/T) and S13_628331 (A/T), were developed and effectively validated in 27 vegetable soybean accessions. Overall, our research identified genes that regulate the pod length and width and determined KASP markers for molecular marker-assisted selection breeding. These findings have crucial implications for the improvement of soybean crops and can contribute to the development of efficient breeding strategies.

Identification and molecular marker development for peel color gene in melon (Cucumis melo L.)

Peel color is an important appearance quality of melons that greatly affects consumer preferences. In this study, a near-isogenic line NIL-G (dark green peel) was generated from B8 (grey-green peel) and B15 (white peel). The F2 population constructed by crossing NIL-G and B15 was used to study the inheritance pattern of peel color, and bulked-segregant analysis sequencing (BSA-seq) was employed to identify the interval in which the target gene was located. Genetic analysis results showed that the dark green peel trait at maturity is controlled by a dominant gene. BSA-seq and molecular markers were used to localize the candidate gene in a 263.7 kb interval of chromosome 4, which contained the CmAPRR2 gene with known functions. Moreover, allelic sequence analysis revealed four SNP variations of the CmAPRR2 gene in B15, of which SNP.G614331A was located at the junction of the 6th exon and 6th intron. The G-to-A mutation caused alternative splicing of the transcript of CmAPRR2 in B15, generating two transcripts (CmAPRR2-A and CmAPRR2-B) with premature termination codons. Furthermore, the Kompetitive Allele Specific PCR (KASP) marker, APRR2-G/A, was developed based on this SNP and shown to co-segregate with the peel color phenotype in the F2 population. Compared to white-peel B15, the expression level of CmAPRR2 in dark green peel NIL-G was higher at each growth stage. Therefore, CmAPRR2 may be the key gene controlling the fruit color of melons. Overall, this study identified a novel allelic variant of CmAPRR2 that leads to white peel formation in mature melons. The study also provides a theoretical basis for further research on the gene regulatory mechanism of melon peel colors and may promote the future use of molecular marker-assisted selection to modify melon peel colors.

Genome-wide association study of salt tolerance at the seed germination stage in lettuce.

Developing lettuce varieties with salt tolerance at the seed germination stage is essential since lettuce seeds are planted half an inch deep in soil where salt levels are often highest in the salinity-affected growing regions. Greater knowledge of genetics and genomics of salt tolerance in lettuce will facilitate breeding of improved lettuce varieties with salt tolerance. Accordingly, we conducted a genome-wide association study (GWAS) in lettuce to identify marker-trait association for salt tolerance at the seed germination stage. The study involved 445 diverse lettuce accessions and 56,820 single nucleotide polymorphism (SNP) markers obtained through genotype-by-sequencing technology using lettuce reference genome version v8. GWAS using two single-locus and three multi-locus models for germination rate (GR) under salinity stress, 5 days post seeding (GR5d_S) and a salinity susceptibility index (SSI) based on GR under salinity stress and control conditions, 5 days post seeding (SSI_GR5d) revealed 10 significant SNPs on lettuce chromosomes 2, 4, and 7. The 10 SNPs were associated with five novel QTLs for salt tolerance in lettuce, explaining phenotyping variations of 5.85%, 4.38%, 4.26%, 3.77%, and 1.80%, indicating the quantitative nature of these two salt tolerance-related traits. Using the basic local alignment search tool (BLAST) within 100 Kb upstream and downstream of each of the 10 SNPs, we identified 25 salt tolerance-related putative candidate genes including four genes encoding for major transcription factors. The 10 significant salt tolerance-related SNPs and the 25 candidate genes identified in the current study will be a valuable resource for molecular marker development and marker-assisted selection for breeding lettuce varieties with improved salt tolerance at the seed germination stage.

A novel strategy to map a locus associated with flowering time in canola (Brassica napus L.).

Flowering time is an important agronomic trait for canola breeders, as it provides growers with options for minimizing exposure to heat stress during flowering and to more effectively utilize soil moisture. Plants have evolved various systems to control seasonal rhythms in reproductive phenology including an internal circadian clock that responds to environmental signals. In this study, we used canola cultivar 'Westar' as a recurrent parent and canola cultivar 'Surpass 400' as the donor parent to generate a chromosome segment substitution line (CSSL) and to map a flowering time locus on chromosome A10 using molecular marker-assisted selection. This CSSL contains an introgressed 4.6 mega-bases (Mb) segment (between 13 and 17.6Mb) of Surpass 400, which substantially delayed flowering compared with Westar. To map flowering time gene(s) within this locus, eight introgression lines (ILs) were developed carrying a series of different lengths of introgressed chromosome A10 segments using five co-dominant polymorphic markers located at 13.5, 14.0, 14.5, 15.0, 15.5, and 16.0Mb. Eight ILs were crossed with Westar reciprocally and flowering time of resultant 16 F1 hybrids and parents were evaluated in a greenhouse (2021 and 2022). Four ILs (IL005, IL017, IL035, and IL013) showed delayed flowering compared to Westar (P < 0.0001), and their reciprocal crosses displayed a phenotype intermediate in flowering time of both homozygote parents. These results indicated that flowering time is partial or incomplete dominance, and the flowering time locus mapped within a 1Mb region between two co-dominant polymorphic markers at 14.5-15.5Mb on chromosome A10. The flowering time locus was delineated to be between 14.60 and 15.5Mb based on genotypic data at the crossover site, and candidate genes within this region are associated with flowering time in canola and/or Arabidopsis. The co-dominant markers identified on chromosome A10 should be useful for marker assisted selection in breeding programs but will need to be validated to other breeding populations or germplasm accessions of canola.

Development of wheat-tetraploid Thinopyrum elongatum 4EL small fragment translocation lines with stripe rust resistance gene Yr4EL.

Two small fragment translocation lines (T4DS·4DL-4EL and T5AS·5AL-4EL) showed high resistance to stripe rust and resistance gene Yr4EL was localized to an about 35 Mb region at the end of chr arm 4EL. Stripe rust, caused by the fungus Puccinia striiformis f. sp. tritici, is a devastating wheat disease worldwide. Deployment of disease resistance (R) genes in wheat cultivars is the most effective way to control the disease. Previously, the all-stage stripe rust R gene Yr4EL from tetraploid Thinopyrum elongatum was introduced into common wheat as 4E(4D) substitution and T4DS·4EL translocation lines. To further map and utilize Yr4EL, Chinese Spring (CS) mutant pairing homoeologous gene ph1b was used in crossing to induce recombination between chromosome (chr) 4EL and wheat chromosomes. Two small fragment translocation lines T4DS·4DL-4EL and T5AS·5AL-4EL with Yr4EL resistance were selected using molecular markers and confirmed by genomic in situ hybridization (GISH), fluorescence in situ hybridization (FISH), and Wheat660K SNP array analyses. We mapped Yr4EL to an about 35Mb region at the end of chr 4EL, corresponding to 577.76-612.97Mb based on the diploid Th. elongatum reference genome. In addition, two competitive allele-specific PCR (KASP) markers co-segregating with Yr4EL were developed to facilitate molecular marker-assisted selection in breeding. The T4DS·4DL-4EL lines were crossed and backcrossed with wheat cultivars SM482 and CM42, and the resulting pre-breeding lines showed high stripe rust resistance and potential for wheat breeding with good agronomic traits. These lines represent new germplasm for wheat stripe rust resistance breeding, as well as providing a solid foundation for Yr4EL fine mapping and cloning.

Advancements in Lentil Genomics for Enhanced Crop Breeding: A Review

Lentil (Lens culinaris Medik) is an essential pulse crop that is widely grown for its high nutritional value, notably its high protein content, making it an important dietary component for vegetarians and vegans. Despite being the world's fifth most produced pulse, with large contributions from Canada and India, lentil production confronts obstacles such as poor productivity due to limited genetic improvement against biotic and abiotic stresses under rainfed cultivation conditions. Recent advances in lentil genetics and genomics, such as the discovery of genes related to yield, disease resistance, and nutritional content, have boosted breeding efforts to generate improved lentil varieties. The use of contemporary genomic techniques like molecular markers, marker-assisted selection (MAS), genomic selection (GS), and next-generation sequencing (NGS) technology has sped up the discovery of quantitative trait loci (QTLs) and the production of novel cultivars with superior agronomic characteristics. Databases such as NCBI and ENA, as well as specialized resources like KnowPulse, provide critical genomic data, while the creation of lentil genome assemblies, notably the CDC Redberry variety, has improved our understanding of lentil genetics. These resources help to solve the constraints of traditional breeding, particularly for complex characteristics impacted by genotype-environment interactions, opening the way for more robust and productive lentil varieties. Although the application of advanced tools such as genetic engineering, cisgenesis, and genome editing has moved more slowly in lentils than in other crops, their potential to improve lentil output is encouraging. Recent studies on lentil genomes, together with the creation of increased genetic resources and cutting-edge techniques, offer the ability to overcome production constraints and dramatically increase lentil production and quality throughout the world.

Genetic Basis and Exploration of Major Expressed QTL qLA2-3 Underlying Leaf Angle in Maize

Leaf angle (LA) is closely related to plant architecture, photosynthesis and density tolerance in maize. In the current study, we used a recombinant inbred line population constructed by two maize-inbred lines to detect quantitative trait loci (QTLs) controlling LA. Based on the average LA in three environments, 13 QTLs were detected, with the logarithm of odds ranging from 2.7 to 7.21, and the phenotypic variation explained by a single QTL ranged from 3.93% to 12.64%. A stable QTL, qLA2-3, on chromosome 2 was detected and was considered to be the major QTL controlling the LA. On the basis of verifying the genetic effect of qLA2-3, a fine map was used to narrow the candidate interval, and finally, the target segment was located at a physical distance of approximately 338.46 kb (B73 RefGen_v4 version), containing 16 genes. Re-sequencing and transcriptome results revealed that five candidate genes may be involved in the regulation of LA. The results enrich the information for molecular marker-assisted selection of maize LA and provide genetic resources for the breeding of dense planting varieties.

TRIM103 activates the RLRs pathway to enhance antiviral response by targeting VP5 and VP7

Grass carp (Ctenopharyngodon idella), crucial to global inland aquaculture with a production of 5.8 million tones in 2020, faces significant challenges from hemorrhagic disease caused by grass carp reovirus (GCRV). Rapid mutations compromise current vaccines, underscoring the need for a deeper understanding of antiviral mechanisms to enhance molecular marker-assisted selection. This study investigates the role of Tripartite Motif (TRIM) family in the innate immune response of grass carp, focusing on TRIM103 from Ctenopharyngodon Idella (CiTRIM103), a member of the TRIM-B30.2 family, which includes proteins with the B30.2 domain at the N-terminus, known for antiviral properties in teleosts. CiTRIM103 bind to the outer coat proteins VP5 and VP7 of GCRV. This binding is theorized to strengthen the function of the RIG-I-like Receptor (RLR) signaling pathway, crucial for antiviral responses. Demonstrations using overexpression and RNA interference (RNAi) techniques have shown that CiTRIM103 effectively inhibits GCRV replication. Moreover, molecular docking and pulldown assays suggest potential binding interactions of CiTRIM103's B30.2 domain with GCRV outer coat proteins VP5 and VP7. These interactions impede viral replication, enhance RLR receptor expression, and activate key transcription factors to induce type I interferons (IFNs). These findings elucidate the antiviral mechanisms of CiTRIM103, provide a foundation for future Molecular genetic breeding in grass carp.

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

BackgroundElucidating 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.ResultIn 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.ConclusionBy 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.

Molecular Marker-Assisted Selection of a New Water-Saving and Drought-Resistant Rice (WDR) Restoration Line, Hanhui 8200, for Enhanced Resistance to Rice Blast

Through backcrossing and marker-assisted selection, gene Pi9 for resistance to rice blast was introduced into the water-saving and drought-resistant rice variety, Hanhui 3. The genetic background identity between Hanhui 8200 and Hanhui 3 was 91.4%. The drought resistance and drought avoidance abilities of Hanhui 8200 were equivalent to those of Hanhui 3. The resistance to rice blast was improved from grade 7 to grade 1. The rice quality of Hanhui 8200 meets the Ministry of Agriculture’s grade 3 rice standards. The two-line and three-line hybrids formulated with Hanhui 8200 have high yield potential. Among them, the three-line hybrid Hanyou 8200 (Approval No.: Evaluated Rice 20210073), formulated with Huhan 7A, passed the Hubei Provincial approval in 2021, and the two-line hybrid Hanyouliangyou 8200 (Approval No.: Nationally Validated Rice 20210448), formulated with Huhan 82S, passed the national variety approval in 2021. Both hybrids demonstrated strong resistance to rice blast, moderate resistance to bacterial leaf blight, strong drought resistance, high quality, and high yield.