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[Genetic diversity analysis of Forsythia suspensa germplasm resources in Shanxi based on phenotypic traits and SNP molecular markers].

This study aimed to clarify the degree of fruit phenotypic variation and the characteristics of genetic diversity, population structure, and genetic differentiation of Forsythia suspensa resources in Shanxi, providing an important basis for germplasm conservation and breeding of superior varieties. A total of 46 F. suspensa fruits were collected, and 12 agronomic traits were measured and analyzed. The population genetic structure and genetic diversity of F. suspensa germplasm were evaluated using simplified genome sequencing technology. For the five quality traits of the 46 fruits, the Shannon-Wiener index ranged from 0.631 to 1.074, and the Simpson index ranged from 0.379 to 0.560. The seven quantitative traits exhibited abundant genetic variation, with coefficients of variation ranging from 9.764%(fruit shape index) to 45.494%(forsythin content). Principal component analysis reduced the 12 phenotypic traits to four factors, with a cumulative variance contribution of 74.547%. Sequencing data showed mean Q20 and Q30 values of 98.13% and 94.33%, respectively, with an average GC content of 35.95%. After filtering, a total of 12 347 327 high-quality single nucleotide polymorphism(SNP) loci were obtained. Based on these high-quality SNPs, principal component analysis, population structure analysis, and phylogenetic tree construction were carried out. The 46 germplasm resources were divided into four groups; however, grouping showed little relationship with geographic origin, and intermixing occurred among regions. Mantel test revealed a significant but weak positive correlation between phenotypic and genetic distances(r=0.159, P=0.001). At the molecular level, the four groups exhibited moderate genetic diversity overall, and the genetic differentiation index among populations ranged from 0.027 to 0.084, indicating low to moderate differentiation. The rich genetic diversity of the main phenotypic traits provides a solid material basis for screening superior germplasm and genetic breeding of F. suspensa.

Forsythia

Construction of a Core Germplasm and Identification of Candidate SNPs Associated with Growth Performance of Epinephelus tukula by Whole-Genome Resequencing.

Epinephelus tukula is an economically important aquaculture animal, and a major parent in grouper crossbreeding. To better preserve and exploit E. tukula germplasm resources, a core collection (containing 34 individuals derived from 10 genetic groups) was first constructed based on phenotypic growth traits and whole-genome resequencing (WGS) data. The phenotypic traits of the individuals within the core collection were not significantly different from those in the original collection, suggesting effective representativeness of the core collection. Additionally, we performed genome-wide association study (GWAS) of E. tukula to identify candidate single nucleotide polymorphisms (SNPs) and genes associated with growth traits, to facilitate the improvements in the growth performance of this species. Twenty-six significant SNPs were identified, scattered among multiple chromosomes. Five SNPs were confirmed to be correlated with growth in another new group of 101 individuals. Based on the annotation results, these five SNPs were located in CCDC102A, NTRK2, CTSL, OTOF, and nestin, and were involved in cell development, differentiation and proliferation, glycolytic metabolism, neurological development, and myoblast differentiation. Our findings not only provide an effective basis for the conservation and utilization of E. tukula germplasm resources, but also promote the development of marker-assisted selection of E. tukula.

Polymorphism, Single Nucleotide

Marker-assisted screening of resistance to fire blight, powdery mildew, and apple scab in local apple varieties from Uzbekistan.

Apple (Malus domestica Borkh.) is one of the most economically important fruit crops worldwide; however, its production is severely constrained by major diseases, including fire blight, powdery mildew, and apple scab. Breeding disease-resistant cultivars represents a sustainable alternative to chemical control, particularly through the effective utilization of local germplasm resources from Central Asia. This study aimed to evaluate the presence and distribution of resistance-associated alleles in local apple varieties from Uzbekistan using polymorphic DNA markers. A collection of local apple accessions was screened to identify markers linked to resistance against fire blight, powdery mildew, and apple scab. The analysis revealed substantial genetic variation in resistance gene combinations among the studied varieties. The fire blight-associated marker AE10-375 was detected in 79.8% of the accessions. For powdery mildew resistance, 75.2% of the varieties carried resistance alleles corresponding to both Pl1 and Pl2 genes. Screening for apple scab resistance demonstrated that Vfa2, Vfa1, and Rvi6 were the most prevalent genes, with Vfa2 detected in 95.4% of the accessions. Regional analysis indicated that accessions from Karakalpakstan exhibited the highest proportion of genotypes harboring markers associated with resistance to multiple diseases. Six local varieties-Atlas olma, Turkish, Xuboni, Krasniy jeleznyak, Shoyi olma, and Besh barmoq-were identified as carrying resistance-associated markers for all three diseases. These findings demonstrate that local apple germplasm from Uzbekistan represents a valuable genetic resource for resistance to economically important diseases. The identified genotypes provide promising donor material for breeding programs aimed at developing cultivars with durable, broad-spectrum resistance while reducing reliance on chemical control strategies.

Malus

Scaling up orphan crop research: genebank genetics highlight geographic structure in cultivated cowpea from 10 617 global accessions.

Vigna unguiculata (L.) Walp. is a dryland legume crop, providing essential food and nutritional security for millions of people across the semi-arid tropics, in Africa, Asia and Latin America. However, as a typical 'orphan crop', cowpea has long remained underrepresented in global genomic research to support crop improvement. Here, we conducted the largest genetic diversity analysis of cowpea to date, comprising 10 617 accessions sourced from seven international collections. Using genotyping-by-sequencing, we characterised the global patterns of genetic diversity, assessed redundancy within and across collections, and examined the geographic structure of the cowpea global allele pool. Our results revealed nine distinct genetic groups with clear geographic associations and fine-scale population differentiation, reflecting dispersal history, regional adaptation and the influence of modern breeding. Duplication across collections was detected, highlighting the need for improved curation and integration of germplasm resources. Landraces from sub-Saharan Africa do not fully capture the genetic diversity present in several other geographic regions, indicating the existence of abundant and untapped genetic resources worldwide. These findings not only provide insights into the genetic structure and evolutionary history of cowpea but also offer a valuable foundation for harnessing global germplasm diversity to enhance breeding potential and accelerate crop improvement.

Vigna

Molecular breeding of tomato: Advances and challenges.

The modern cultivated tomato (Solanum lycopersicum) was domesticated from Solanum pimpinellifolium native to the Andes Mountains of South America through a "two-step domestication" process. It was introduced to Europe in the 16th century and later widely cultivated worldwide. Since the late 19th century, breeders, guided by modern genetics, breeding science, and statistical theory, have improved tomatoes into an important fruit and vegetable crop that serves both fresh consumption and processing needs, satisfying diverse consumer demands. Over the past three decades, advancements in modern crop molecular breeding technologies, represented by molecular marker technology, genome sequencing, and genome editing, have significantly transformed tomato breeding paradigms. This article reviews the research progress in the field of tomato molecular breeding, encompassing genome sequencing of germplasm resources, the identification of functional genes for agronomic traits, and the development of key molecular breeding technologies. Based on these advancements, we also discuss the major challenges and perspectives in this field.

Solanum lycopersicum

Landscape Genomics Reveals Divergent Adaptation Modes and Predicts Climate Vulnerability in Xinjiang Indigenous Sheep.

Climate change increasingly endangers precious indigenous sheep germplasm resources distributed across diverse Chinese landscapes, and systematically decoding their polygenic climate-adaptive genetic mechanisms is essential for targeted breed conservation and long-term sustainable pastoral production. Whole-genome resequencing data from 93 individuals covering six representative local sheep breeds were analyzed in this work. After filtering highly collinear climate variables, three mature landscape genomic approaches were jointly applied to identify environment-linked gene variants, while two predictive metrics across ten CMIP6 future climate scenarios quantified each breed's long-term adaptive risks. Six temperature- and water-related environmental factors jointly drove sheep population genetic differentiation, with temperature fluctuation indices showing markedly stronger explanatory power. Detected adaptive genes were significantly enriched in ion transport, energy metabolism and cellular stress response pathways. Future projections indicated western breeds (Bayinbuluke, Cele Black, Xiahe) face severe maladaptation risks under high-emission SSP370 scenarios by 2100, whereas central and eastern breeds possess much broader climate tolerance. This study systematically reveals the core genomic basis of ovine climate adaptation and quantifies distinct breed-specific climate vulnerability, providing solid reliable theoretical support for precision germplasm conservation and selective breeding of climate-resilient sheep varieties.

adaptive loci

A CRISPR/Cas9 mutant resource for OsSm RNA-binding genes in rice.

Pre-mRNA, produced by eukaryotic DNA transcription, undergoes splicing by the spliceosome, which removes introns and joins exons to form mRNA. The spliceosome is a large and highly dynamic molecular machine. Its core components include five small nuclear ribonucleoproteins (snRNPs) and the various spliceosome-related proteins. The conserved Smith (Sm) complex and the Sm-like proteins (LSm) serve as primary components of the snRNPs. Sm proteins are involved in processes such as pre-mRNA splicing and mRNA degradation, which can regulate gene expression, thereby influencing plant growth, development, and stress responses. While 25 Sm proteins have been identified in rice, their specific roles in regulating rice growth and development remain unclear. In this study, we employed the CRISPR/Cas9 system to edit 15 OsSm genes, and 13 mutants were obtained, with mutation rates ranging from 20.83 to 83.87%. In comparison to the wild type (WT), the mutants exhibited dwarfism, reduced tiller numbers, lower seed-setting rates or sterility, and increased susceptibility to diseases. One Sm mutant, ossmf-2, exhibited dwarfism, delayed flowering, and small grains. Through transcriptome analysis, three target genes, OsMRG702, OsRGG2, and OsLA1, were identified. Mutations of the OsSmF protein may lead to the abnormal splicing of these genes and finally lead to the inhibition of growth and development. Our study first edited the OsSm genes and generated a mutant library in rice. Most of the mutants exhibited abnormal growth and development, underscoring the essential roles of OsSm proteins in rice physiology. Furthermore, this work addresses a critical gap in the functional characterization of Sm proteins in rice. The resulting mutant collection offers valuable germplasm resources and lays a theoretical foundation for elucidating the molecular regulatory networks involving spliceosomal components and their target genes in the control of crop growth, development, and reproduction.

Oryza

Transcription factor NtELF3 promotes the polyphenol accumulation by targeting NtFLS-1 and NtCHIL-2 genes in tobacco.

Tobacco (Nicotiana tabacum L.) is an important economic crop, from which polyphenols are crucial for regulating its growth and development as well as shaping its quality. However, few genes associated with polyphenol accumulation have been cloned from tobacco, and the molecular mechanisms underlying this process remain poorly understood. Here, we found that the tobacco transcription factor EARLY FLOWERING 3 (NtELF3), which is highly expressed in tobacco leaves, positively regulates the accumulation of chlorogenic acid, neochlorogenic acid, cryptochlorogenic acid, rutin, scopoletin, and total polyphenols in tobacco middle leaves. The metabolomic and transcriptomic analyses of middle leaves showed that a total of 177 differentially accumulated metabolites and 7409 differentially expressed genes (DEGs) were identified in ntelf3-1 mutant versus wild type, respectively. Further investigation identified that 17 DEGs were involved in phenylpropanoid metabolic and flavonoid metabolic processes. Combined analysis indicated that the phenylpropanoid and flavonoid biosynthesis pathways were also co-enriched in kyoto encyclopedia of genes and genomes enrichment analysis. Molecular biology experiment demonstrated that NtELF3 directly binds to the promoters of NtFLS-1 and NtCHIL-2 that are both associated with phenylpropanoid and flavonoid biosynthesis, and promotes their expression. Taken together, our results not only provide new theoretical support for in-depth understanding of the regulatory mechanisms underlying polyphenol accumulation in tobacco, but also offer excellent genes and germplasm resources for tobacco quality breeding.

NtCHIL

High-quality chromosome-level genome of three Meretrix species using Nanopore and Hi-C technologies.

Meretrix is a commercially valuable bivalve genus in Asia, but only one reference genome has hindered comprehensive genetic studies and germplasm resource evaluation. In this study, we present three reference genomes of Meretrix species: Meretrix sp. MF1, Meretrix sp. MT1, and Meretrix lamarckii JML1. Meretrix sp. MF1 was assembled at the chromosome level using Nanopore sequencing and Hi-C technologies, whereas Meretrix sp. MT1 and Meretrix lamarckii were assembled as scaffold-level assemblies. The chromosome-level genome of Meretrix sp. MF1 consists of 36 contigs, including 19 chromosomes and 17 scaffolds, with a total length of 883.3 Mb and a scaffold N50 of 46.87 Mb. Notably, the genome of Meretrix sp. MF1, a putative novel species, exhibits an Average Nucleotide Identity (ANI) of 94.33% with its closest relative, Meretrix lamarckii. These genomic resources not only provide a crucial foundation for genetic research on Meretrix but also contribute to the development of effective conservation strategies for its sustainable management.

Animals

Large-Scale Genomic Analysis of Stripe Rust Resistance in Chinese Wheat Germplasm Using Multi-Environment Trial Data.

Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is a significant disease affecting global wheat crops and causing substantial economic losses. This study aimed to identify effective resistance genes by evaluating 120 common wheat accessions from diverse regions in China. These samples were tested with three Pst races at the seedling stage and with natural Pst inoculum at four field locations in three crop seasons. Genotypic data were collected through a Wheat55K iSelect single-nucleotide polymorphism array. The genome-wide association study identified 17 distinct loci linked to stripe rust response, accounting for 1.07 to 30.58% of the phenotypic variation across trials. These loci were distributed among three wheat genome groups: 2 in Group A, 10 in Group B, and 5 in Group D. Among these, eight loci overlapped with the reported stripe rust resistance genes or quantitative trait loci, while nine loci were novel and mainly distributed on chromosomes 2A, 6B, and 7D. This research enhances the understanding of genetic mechanisms underlying wheat stripe rust resistance and provides valuable germplasm resources for breeding new cultivars with enhanced disease resilience.

Puccinia striiformis f. sp. tritici

A robust biotechnology induces artificial genomic duplication via transient RNAi-mediated suppression of OSD1 in rice.

Ploidy manipulation is a crucial strategy for generating germplasm in crop breeding. However, artificial genomic duplication, often induced by colchicine treatment, is associated with toxicity and unpredictability. Although mutations in OSD1 have shown promise for inducing genomic duplication, the instability of ploidy across generations limits their practical application. In this study, we developed a Plant Polyploidization via Gene Interference (PPGI) system that utilizes transient RNAi-mediated suppression of OSD1 to efficiently induce artificial genomic duplication, demonstrating obvious potential for producing autotetraploids. We first validated this system by successfully generating PPGI-induced autotetraploid plants from the Taichung65 cultivar. These PPGI-induced plants exhibited notable differences from Taichung65 but resembled the existing Taichung65-4x line obtained through colchicine treatment. Haplotype analysis indicated that the OSD1 RNAi fragment is conserved across 2,908 rice cultivars. Consequently, we employed the same PPGI vector to develop autotetraploid lines from various germplasms, including another japonica cultivar, seven indica cultivars, and one Oryza rufipogon line. The probability of genomic duplication achieved by our PPGI method was higher than that obtained by colchicine treatment. Typically, autotetraploid lines exhibit severe sterility in the first generation following polyploidization. Leveraging fertile neo-tetraploid rice and the PPGI system, we designed and verified two strategies to directly induce fertile autotetraploid germplasms in the first generation, thereby substantially shortening the breeding cycle. Our method provides a universal, efficient, and non-toxic approach for inducing autotetraploid rice germplasms and contributes to enriching fertile autotetraploid rice germplasm resources.

OSD1

SUG2 controls grain size and weight by influencing GS2 transcription level in rice.

Grain size is a critical yield determinant and a complex quantitative trait in rice. The major quantitative trait locus GS2, which encodes the transcriptional regulator OsGRF4, has been characterized as a key controller of grain size and grain weight in rice. Building upon existing germplasm resources, exploring the upstream and downstream genes of known grain size regulators is an effective approach to gradually refine and expand the molecular regulatory network underlying grain size. Here, we report that a suppressor of the gain-of-function allele GS2AA, SUG2, which encodes an importin β nuclear transport protein. Phenotypic characterization reveals that the sug2 GS2AA mutant exhibits small grains by inhibiting cell expansion in the spikelet hull. Protein interaction analyses demonstrate that SUG2 physically interacts with GS2 both in vivo and in vitro, and the SUG2A mutation reduces SUG2 expression levels and inhibits GS2 transcriptional activation activity, resulting in decreased GS2 expression levels and GS2 protein abundance in sug2 GS2AA. Genetic analyses indicate that SUG2 and GS2 may be partially involved in a common pathway regulating grain size and weight in rice. These findings elucidate the grain size regulatory relationship between SUG2 and GS2 and provide novel insights into the precision breeding of yield optimization in rice.

Oryza

Development and validation of whole-genome SSR markers in sugar beet (Beta vulgaris L.).

Sugar beet (Beta vulgaris L.) is an important sugar and cash crop worldwide. To systematically characterize SSR (Simple Sequence Repeat) loci across sugar beet chromosomes and enable the precise identification of germplasm resources, this study conducted a genome-wide scan for SSR loci, analyzed their distribution patterns, and determined their genotypes using resequencing data from 123 sugar beet varieties. The results revealed an abundance of SSR loci in the sugar beet genome, with a total of 135, 379 identified, from which 135, 344 pairs of SSR primers were designed (135, 344 primer pairs successfully designed; 35 loci failed to meet design criteria). Specifically, 31, 748 primer pairs were designed based on SSRs located in unassigned scaffolds, and 103, 596 primer pairs from SSRs assigned to the nine chromosomes. Through bioinformatic analysis, we identified 28, 768 SSR primers located in multi-copy genes with PIC (Polymorphism Information Content) ≥ 0.5, and 2, 326 SSR markers located in single-copy genes residing in various genic regions (among which 543 had PIC ≥ 0.5, with the highest reaching 0.776). PCR (Polymerase Chain Reaction) validation confirmed 20 robust and polymorphic markers producing clear and reproducible bands. Among them, 10 SSR primers located in multi-copy genes exhibited three or more polymorphic types, and 10 markers located in single-copy genes displayed 2-3 polymorphic types. The most polymorphic marker, YCD-4-2, detected 11 polymorphic types across 48 varieties. Furthermore, to explore markers with potential functional significance, we annotated the genes harboring SSR markers located in single-copy genes. The results showed that 1, 264 SSRs located in single-copy genes were localized to 967 genes, which are significantly enriched in pathways related to carbohydrate metabolism, stress responses, and plant-pathogen interactions. The 20 validated markers and the 2, 326 SSRs located in single-copy genes provided in this study can be directly applied to fingerprinting of sugar beet varieties, seed purity testing, and marker-assisted selection, thus representing a practical resource for molecular breeding.

genome-wide

Genome-Wide Characterization of the ZIP Transporter Family in Sea Island Cotton (Gossypium barbadense L.) and Expression Profiling Under Heavy Metal and Pathogen Stresses.

G. barbadense represents an indispensable germplasm resource for high-quality textile fiber and disease resistance; nevertheless, systematic information regarding its ZRT/IRT-like protein (ZIP) gene family remains limited. Here, a total of 46 GbZIP genes were identified across the G. barbadense genome. Comprehensive bioinformatic investigations revealed uneven chromosomal distribution and confirmed that segmental/whole-genome duplications, supplemented by localized tandem duplications, drove family expansion. Members clustered within the same phylogenetic clades shared conserved motif organization and gene architecture, while promoter regions harbored abundant cis-acting elements associated with phytohormone and stress signaling. Transcriptome profiling indicated distinct expression patterns across vegetative/reproductive tissues, fiber and ovule developmental stages, and diverse abiotic stress conditions (cold, hot, drought, and salt). Quantitative Real-Time PCR (qRT-PCR) further validated that several GbZIP candidates exhibited temporal expression variations upon exposure to cadmium toxicity, V. dahliae infection, and combined Cd-V. dahliae stress. Specifically, GbZIP13, GbZIP18, GbZIP27, and GbZIP36 displayed prominent broad-spectrum responses to all three stress conditions, whereas GbZIP16, GbZIP29, and GbZIP30 showed stress-specific regulatory divergence. Overall, this study aims to systematically analyze the evolutionary characteristics and expression patterns of the GbZIP family, and to specifically evaluate the response differences under Cd stress, V. dahliae stress, and combined stress, in order to identify potential key candidate genes.

Gossypium barbadense

Genetic Analysis of Genomic and Methylomic Variation and Identification of Multi-Trait Mutants in Rice Carried on Chang'e-5.

Global food security is facing challenges from population growth to diminishing arable land. Space mutation breeding holds promise for overcoming the variation limitations in conventional breeding; however, the mutagenic effects of the deep-space environment on rice and the transgenerational inheritance patterns of induced variations remain unclear. In this study, rice seeds carried by the Chang'e-5 spacecraft were used as materials. Whole-genome sequencing and whole-genome bisulfite sequencing were performed on the first (SP1) and second generations (SP2) of space-mutagenized plants after their return to Earth. The results showed that the number of genomic variants in the SP2 generation increased significantly compared with SP1, and SNPs, homozygous sites, and variants in coding regions were more heritable. The genome-wide methylation level was elevated in the SP2 generation, and among differentially methylated cytosines, those in the CG context exhibited the highest heritability. Furthermore, large-scale screening for nitrogen efficiency, tolerance to PEG-induced stress, and germination-stage cold resistant mutants was conducted in the SP2 generation, and phenotypic validation was performed in the third generation (SP3). By integrating multi-omics analyses of representative mutants to mine candidate genes, a number of heritable elite mutants were obtained, and seven candidate genes for key traits were identified. This study systematically elucidates the transgenerational inheritance patterns of deep-space-induced variation in rice. The multi-trait mutants obtained provide valuable germplasm resources for gene cloning and breeding applications in rice.

DNA methylation

Pan-genome-based resequencing of 2,320 accessions reveals structural variations and accelerates breeding advances in cultivated peanut.

The cultivated peanut is a crucial global legume crop that is essential for food security and nutrition, particularly in developing regions. However, its limited genetic variation hampers breeding progress and yield improvement. Here we constructed a graph-based pan-genome for peanut, incorporating 14 genomes that represent all 6 peanut varieties. Using this pan-genome, we genotyped 2,320 accessions, covering 88.03% of ICRISAT and 59.21% of USDA core germplasm, enriching valuable resources for genomic studies and breeding. We cataloged genomic structural variations and investigated the role of homoeologous exchanges in population divergence. Through our pan-genome approach, we overcame the challenges of genotyping posed by homoeologous exchanges and identified key genes associated with flowering and dwarfism in peanut. By integrating superior haplotypes and germplasm resources guided by the pan-genome, we further developed high-yield dwarf lines. This work provides essential genomic resources to accelerate functional gene discovery and modern peanut breeding.

Journal Article

Cytotype classification and genetic diversity of Platostoma palustre revealed by rDNA localization and chloroplast genome.

BACKGROUND: Platostoma palustre A. J. Paton is an edible medicinal plant that plays a significant role in traditional food production and medicinal applications. However, the genetic basis of P. palustre remains unclear, thereby hampering research on its genome and polyploid evolution. RESULTS: To characterize the karyotype and ploidy of P. palustre, we performed fluorescence in situ hybridization (FISH) by using 35 S and 5 S rDNA probes in P. palustre. FISH results indicated that 35 S rDNA mapped to the end of the chromosome (chromosome satellite, heterochromatic region) and that 5 S rDNA was located close to the centromere of the chromosomes. Based on the rDNA sites, we identified three distinct cytotypes of P. palustre: diploid (2n = 2x = 30, x = 15), triploid (2n = 3x = 45, x = 15), and tetraploid (2n = 4x = 60, x = 15). To further explore the genetic evolutionary relationship among these P. palustre cytotypes, we conducted Illumina sequencing and assembled the chloroplast (CP) genome. The CP genomes of P. palustre accessions maintained a conserved single circular molecule with a length of 152,534 - 152,788 bp, comprising a large single-copy region (LSC) and small single-copy region (SSC) separated by two inverted repeat regions (IRs). Phylogenetic trees were also created based on CP and nuclear molecular markers, showing that most P. palustre accessions clustered together corresponding to their collection regions. Of these, GDZC2 (2n = 2x = 30) clustered with several triploid accessions, suggesting that it may share a common ancestor with these triploid accessions. CONCLUSIONS: This is the first study to characterize the karyotype, identify three cytotypes of P. palustre using FISH, and provide molecular evidence for an evolutionary relationship among different P. palustre accessions. These findings will be useful for further genomic studies and polyploid evolution of P. palustre.

Genome, Chloroplast

Genomic prediction-aided incorporation of genetic resources into elite breeding: lessons from a collaborative multiparental design in flint maize.

A public private cooperative mating design between elite maize inbred lines and diversity donors shows that genomic prediction holds great promise to improve the use of genetic resources. Genetic diversity is essential for plant breeding, enabling long-term gains and adaptation to climate change and new agronomical practices. Breeders can access diverse genetic resources to enhance elite germplasm and introduce new favorable variations. The limited performance of genetic resources may hamper their use. To overcome this, a bridging population can be implemented to evaluate and select progenies from crosses between diversity donors and elite lines before their introduction in breeding programs. The choice of such crosses can be dealt with the usefulness criterion (UC), which determines its ability to produce transgressive individuals. This paper investigates the use of genome-wide marker effects to predict (i) the performance of individuals derived from crosses between donors and elite lines and (ii) the UC of crosses not observed yet. It also compares donor introduction strategies based on the UC or the H criterion, which considers the genome-wide donor-elite complementarity. We used a flint maize collaborative multi-parental BC1-S2 population, consisting in materials from six breeding companies and one public institute crossed to different donors. The 20 crosses had contrasted means and genetic variances, and most of them presented transgressive individuals above the elite parent. Results emphasize the importance of half-siblings derived from the elite line parent of the predicted cross to efficiently predict progeny performances or the UC. They also showed that using the H criterion appears promising to select iteratively donors that best complement initial elite materials. The paper concludes with guidelines for implementing a bridging population using genome-wide marker-based predictions.

Zea mays