Biology subjects

Emeriewen, O. F.

Publications and source records attributed to Emeriewen, O. F..

6 recordsLinked to original sources

bioRxiv2026

Inoculation of Malus baccata 'Jackii'-derived offspring and QTL analysis reveal a polygenic inheritance pattern of apple blotch resistance

Apple blotch, caused by Diplocarpon coronariae, is an increasingly important fungal disease that leads to premature leaf fall and significant yield losses in apple orchards. Breeding resistant cultivars offers a sustainable strategy to reduce disease impact, as all commercial apple cultivars are susceptible to this pathogen. This study aimed to investigate the disease resistance of Malus baccata Jackii-derived offspring to D. coronariae through artificial inoculation and to identify loci associated with resistance. Simple interval mapping was performed using phenotypic and genotypic data from 122 individuals of an F1 population (Idared x M. baccata Jackii), together with analyses of M. baccata Jackii-derived open-pollinated populations. Our results indicate that resistance to apple blotch is a complex, polygenic trait, with four important QTLs identified on linkage groups 1, 2, 12 and 13. Disease severity was strongly affected by inoculum, phenotyping method and environmental factors. These findings have direct implications for apple breeding programmes aimed at developing apple blotch-resistant cultivars.

genetics↗

bioRxiv2025

Genetic mapping, marker development, and identification of candidate genes for powdery mildew resistance in Malus baccata 'Jackii'

Powdery mildew, caused by Podosphaera leucotricha, is one of the most important fungal diseases in apple cultivation worldwide. Malus baccata Jackii, however, exhibits resistance to this pathogen, and a previous study demonstrated that this resistance co-segregates with an AFLP marker on linkage group 10. The objectives of this study were to construct genetic linkage maps, develop molecular markers, and identify candidate genes associated with this powdery mildew resistance, making use of the Malus baccata Jackii genome sequence. An F1 population derived from the cross Idared x Malus baccata Jackii was phenotyped from 2009-11 and 2023-24 and genotyped with SNPs generated from tGBS and SSRs. Genetic linkage maps of Malus baccata Jackii were constructed, and QTL mapping confirmed the presence of the powdery mildew resistance locus Plbj on linkage group 10. In addition, a minor QTL was detected on linkage group five. Closely linked SSR and KASP markers were developed, and the Plbj locus was delimited to a 3,287,286-bp region on haplotype one of the Malus baccata Jackii genome, in which resistance gene candidates were identified. This study supports the direct application of molecular markers in breeding programmes and provides an essential background for future functional studies of Plbj.

genetics↗

bioRxiv2025

High-quality haplotype-resolved genome assembly and annotation of Malus baccata 'Jackii'

Malus baccata Jackii has been observed to exhibit multiple disease resistances, thus rendering it a promising source for breeding new disease-resistant apple cultivars. Here, we present the first haplotype-resolved genome assembly and annotation of this genotype, achieved by integrating PacBio HiFi sequencing, Hi-C, and mRNA sequencing data with a range of bioinformatic tools and databases. The genome assembly comprises 17 pseudochromosomes with total scaffold lengths of 654.6 Mb and 637.5 Mb for the two haplotypes, respectively. Both haplotypes have scaffold N50 values exceeding 30 Mb, with 42,441 and 46,507 predicted genes, of which 99.9% were successfully annotated. The high quality of this genome is supported by BUSCO analysis values exceeding 97.5% for both haplotypes. This comprehensive dataset is well suited for a wide range of future genomic analyses and is anticipated to benefit apple breeding, particularly in the context of enhancing disease resistance.

genomics↗

bioRxiv2023

The structure of the tetraploid sour cherry 'Schattenmorelle' (Prunus cerasus L.) genome reveals insights into its segmental allopolyploid nature

Sour cherry (Prunus cerasus L.) is an economically important allotetraploid cherry species believed to have evolved in the Caspian Sea and Black Sea regions. How, when and where exactly the evolution of this species took place is unclear. It resulted from a hybridization of the tetraploid ground cherry (Prunus fruticosa Pall.) and an unreduced (2n) pollen of the diploid ancestor sweet cherry (P. avium L.). Some indications implement that the genome of sour cherry is segmental allopolyploid, but how it is structured and to what extent is unknown. To get an insight, the genome of the sour cherry cultivar Schattenmorelle was sequenced at ~400x using Illumina NovaSeqTM short-read and Oxford Nanopore long-read technologies (ONT R9.4.1 PromethION). Additionally, the transcriptome of Schattenmorelle was sequenced using PacBio Sequel II SMRT cell sequencing at ~300x. The final assembly resulted in a ~629 Mbp long pseudomolecule reference genome, which could be separated into two subgenomes each split into eight chromosomes. Subgenome PceS_a which originates from P. avium has a length of 269 Mbp, whereas subgenome PceS_f which originates from P. fruticosa has a length of 299.5 Mbp. The length of unassembled contigs was 60 Mbp. The genome of the sour cherry shows a size-reduction compared to the genomes of its ancestral species. It also shows traces of homoeologous sequence exchanges throughout the genome. Comparative positional sequence and protein analyses provided evidence that the genome of sour cherry is segmental allotetraploid and that it has evolved in a very recent event in the past.

genomics↗

bioRxiv2021

Detection of an unstable minor QTL linked to fire blight resistance on linkage group 16 of Malus fusca

ObjectiveErwinia amylovora causes fire blight disease in Malus. A strong resistance QTL (Mfu10) was previously detected on linkage group 10 of Malus fusca accession MAL0045, using several strains of the bacterium. As no strain capable of breaking the resistance of MAL0045 has been found, it was hypothesized that a second resistance factor contributes to the fire blight resistance of MAL0045. However, to date, no minor locus has been detected with previously published strains of the bacterium. We detected a minor QTL only on a subset of a population following inoculation with strain Ea1038, which heterologously expresses an effector in a derivative of isolate Ea3049. Two genetic maps of MAL0045, one scarce, the other dense with markers, were used for QTL analyses. ResultsMfu10 was detected on LG10 with Ea1038, as was previously with Ea3049. Although no other QTLs of significant LOD was previously detected in other linkage groups with Ea3049, a QTL of significant LOD was detected on LG16 (Mfu16) after inoculation of a subset of 76 individuals with Ea1038, but only using the dense genetic map. Mfu16 improved the effect of Mfu10. However, when the number of individuals inoculated with Ea1038 was increased to 121, Mfu16 was no longer detected in the dense genetic map. We hypothesize some factors, which might be responsible for the instability of this QTL.

genetics↗

bioRxiv2021

The draft chromosome-level genome assembly of tetraploid ground cherry (Prunus fruticosa Pall.) from long reads

BackgroundCherries are stone fruits and belong to the economically important plant family of Rosaceae with worldwide cultivation of different species. The ground cherry, Prunus fruticosa Pall. is one ancestor of cultivated sour cherry, an important tetraploid cherry species. Here, we present a long read chromosome-level draft genome assembly and related plastid sequences using the Oxford Nanopore Technology PromethION platform and R10.3 pore type. FindingThe final assemblies obtained from 117.3 Gb cleaned reads representing 97x coverage of expected 1.2 Gb tetraploid (2n=4x=32) and 0.3 Gb haploid (1n=8) genome sequence of P. fruticosa were calculated. The N50 contig length ranged between 0.3 and 0.5 Mb with the longest contig being [~]6 Mb. BUSCO estimated a completeness between 98.7 % for the 4n and 96.1 % for the 1n datasets. Using a homology and reference based scaffolding method, we generated a final consensus genome sequence of 366 Mb comprising eight chromosomes. The N50 scaffold was [~]44 Mb with the longest chromosome being 66.5 Mb. The repeat content was estimated to [~]190 Mb (52 %) and 58,880 protein-coding genes were annotated. The chloroplast and mitochondrial genomes were 158,217 bp and 383,281 bp long, which is in accordance with previously published plastid sequences. ConclusionThis is the first report of the genome of ground cherry (P. fruticosa) sequenced by long read technology only. The datasets obtained from this study provide a foundation for future breeding, molecular and evolutionary analysis in Prunus studies.

genomics↗