Rvi4 and Rvi15 are the same apple scab resistance genes
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ABSTRACT:
SUBMITTER: Peil A
PROVIDER: S-EPMC10564682 | biostudies-literature | 2023 Oct
REPOSITORIES: biostudies-literature
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Project description:Identification of scab resistant genes in apple varieties. The research was funded by SERB.
2020-09-01 | GSE132387 | GEO
Project description:Comparative analyze at the transcriptomic level 1) of Venturia inaequalis apple host resistance via the major resistance gene Rvi6, in Rvi6 overexpressing transgenic apple versus ‘Gala’ susceptible variety; 2) of Venturia pyrina apple nonhost resistance, in ‘Gala’ variety, 24 and 72 hours post inoculation.
2020-10-08 | GSE159179 | GEO
Project description:The evolution of azole resistance in fungal pathogens presents a major challenge in both crop production and human health. Apple orchards across the world are faced with the emergence of azole fungicide resistance in the apple scab pathogen Venturia inaequalis. Target site point mutations observed in this fungus to date cannot fully explain the reduction in sensitivity to azole fungicides. Here, polygenic resistance to tebuconazole was studied across a population of V. inaequalis. Genotyping by sequencing allowed Quantitative Trait Loci (QTLs) mapping to identify the genetic components controlling this fungicide resistance. Dose-dependent genetic resistance was identified, with distinct genetic components contributing to fungicide resistance at different exposure levels. A QTL within linkage group seven explained 65% of the variation in the effective dose required to reduce growth by 50% (ED50). This locus was also involved in resistance at lower fungicide doses (ED10). A second QTL in linkage group one was associated with dose-dependent resistance, explaining 34% of variation at low fungicide doses (ED10), but did not contribute to resistance at higher doses (ED50 and ED90). Within QTL regions, non-synonymous mutations were observed in several ATP-Binding Cassette and Major Facilitator SuperFamily transporter genes. These findings provide insight into the mechanisms of fungicide resistance that have evolved in horticultural pathogens. Identification of resistance gene candidates supports the development of molecular diagnostics to inform management practices.
| S-EPMC10744243 | biostudies-literature
Project description:Among the fungal diseases of apple trees, serious yield losses are due to an apple scab caused by Venturia inaequalis. Protection against this disease is based mainly on chemical treatments, which are currently very limited. Therefore, it is extremely important to introduce cultivars with reduced susceptibility to this pathogen. One of the important sources of variability for breeding is the process of polyploidization. Newly obtained polyploids may acquire new features, including increased resistance to diseases. In our earlier studies, numerous tetraploids have been obtained for several apple cultivars with 'Free Redstar' tetraploids manifesting enhanced resistance to apple scab. In the present study, tetraploids of 'Free Redstar' were assessed in terms of phenotype and genotype with particular emphasis on the genetic background of their increased resistance to apple scab. Compared to diploid plants, tetraploids (own-rooted plants) were characterized with poor growth, especially during first growing season. They had considerably shorter shoots, fewer branches, smaller stem diameter, and reshaped leaves. In contrast to own-rooted plants, in M9-grafted three-year old trees, no significant differences between diplo- and tetraploids were observed, either in morphological or physiological parameters, with the exceptions of the increased leaf thickness and chlorophyll content recorded in tetraploids. Significant differences between sibling tetraploid clones were recorded, particularly in leaf shape and some physiological parameters. The amplified fragment length polymorphism (AFLP) analysis confirmed genetic polymorphism of tetraploid clones. Methylation-sensitive amplification polymorphism (MSAP) analysis showed that the level of DNA methylation was twice as high in young tetraploid plants as in a diploid donor tree, which may explain the weaker vigour of neotetraploids in the early period of their growth in the juvenile phase. Molecular analysis showed that 'Free Redstar' cultivar and their tetraploids bear six Rvi genes (Rvi5, Rvi6, Rvi8, Rvi11, Rvi14 and Rvi17). Transcriptome analysis confirmed enhanced resistance to apple scab of 'Free Redstar' tetraploids since the expression levels of genes related to resistance were strongly enhanced in tetraploids compared to their diploid counterparts.
| S-EPMC7825683 | biostudies-literature
Project description:Endophytic fungi are microorganisms with the ability to colonize plants for the entire or at least a significant part of their life cycle asymptomatically, establishing a plant-fungus association. They play an important role in balancing ecosystems, as well as benefiting host through increasing plant growth, and protecting the host plants from abiotic and biotic stresses using various strategies. In the present study, endophytic fungi were isolated from wild and endemic apple cultivars, followed by characterizing their antifungal effect against Venturia inaequalis. To characterize the endophytic fungi, 417 fungal strains were separated from 210 healthy fruit, leaf, and branch samples collected from the north of Iran. Among the purified fungal isolates, 33 fungal genera were identified based on the morphological characteristics, of which 38 species were detected according to the morphological features and molecular data of ITS, tef-1α, and gapdh genomic regions (related to the genus). The results represented that most of the endophytic fungi belonged to Ascomycota (67.8%), 31.4% of isolates were mycelia sterilia, while the others were Basidiomycota (0.48%) and Mucoromycota (0.24%). Additionally, Alternaria, Cladosporium, and Nigrospora were determined as the dominant genera. The antifungal properties of the identified isolates were evaluated against V. inaequalis in vitro to determine the release of media-permeable metabolites, Volatile Organic Compounds (VOCs), chitinase, and cellulase as antifungal mechanisms, as well as producing phosphate solubilisation as growth-promoting effect. Based on the results of metabolite and VOC tests, the six isolates of Acremonium sclerotigenum GO13S1, Coniochaeta endophytica 55S2, Fusarium lateritium 61S2, Aureobasidium microstictum 7F2, Chaetomium globosum 2S1 and Ch. globosum 3 L2 were selected for greenhouse tests. Further, Co. endophytica 55S2 and F. lateritium 61S2 could solubilize inorganic phosphate. All isolates except Ch. globosum 3 L2 exhibited cellulase activity, while chitinase activity was observed in Ch. globosum 2S1, Ch. globosum 3 L2, and F. lateritium 61S2. Finally, Co. endophytica 55S2 and Ch. globosum 2S1 completely controlled the disease on the apple seedling leaves under greenhouse conditions.
| S-EPMC9677113 | biostudies-literature
Project description:Apple scab, caused by the fungal pathogen Venturia inaequalis, is one of the most severe diseases of apple worldwide. It is the most studied plant-pathogen interaction involving a woody species using modern genetic, genomic, proteomic and bioinformatic approaches in both species. Although 'Geneva' apple was recognized long ago as a potential source of resistance to scab, this resistance has not been characterized previously. Differential interactions between various monoconidial isolates of V. inaequalis and six segregating F1 and F2 populations indicate the presence of at least five loci governing the resistance in 'Geneva'. The 17 chromosomes of apple were screened using genotyping-by-sequencing, as well as single marker mapping, to position loci controlling the V. inaequalis resistance on linkage group 4. Next, we fine mapped a 5-cM region containing five loci conferring both dominant and recessive scab resistance to the distal end of the linkage group. This region corresponds to 2.2 Mbp (from 20.3 to 22.5 Mbp) on the physical map of 'Golden Delicious' containing nine candidate nucleotide-binding site leucine-rich repeat (NBS-LRR) resistance genes. This study increases our understanding of the complex genetic basis of apple scab resistance conferred by 'Geneva', as well as the gene-for-gene (GfG) relationships between the effector genes in the pathogen and resistance genes in the host.
| S-EPMC6638522 | biostudies-literature
Project description:The Vf gene from the wild species Malus floribunda 821 is the most studied apple scab resistance gene. Several molecular markers mapping around this gene were the starting point for a positional cloning project. The analysis of the bacterial artificial chromosome clones spanning the Vf region led to the identification of a cluster of genes homologous to the Cladosporium fulvum resistance gene family of tomato. One of these genes, HcrVf2 (homologue of the C. fulvum resistance genes of the Vf region), was used to transform the susceptible apple cultivar Gala. Four independent transformed lines resistant to apple scab were produced, proving that HcrVf2 is sufficient to confer scab resistance to a susceptible cultivar. The results show that direct gene transfer between cross-compatible species can be viable when, as in apple, the use of backcrosses to introduce resistance genes from wild species cannot exactly reconstitute the heterozygous genotype of clonally propagated cultivars.
| S-EPMC321776 | biostudies-literature
Project description: Not available
| S-EPMC10873587 | biostudies-literature
Project description:Apple scab, a fungal disease caused by Venturia inaequalis, leads to losses in both yield and fruit quality of apples (Malus domestica Borkh.). Most commercial apple cultivars, including those containing the well-characterized Rvi6-scab-resistance locus on linkage group (LG) 1, are susceptible to scab. HcrVf2 and HcrVf1 are considered the main paralogs of the Rvi6 locus. The major apple scab-resistance loci Vhc1 in "Honeycrisp" and Rvi17 in "Antonovka," were identified in close proximity to HcrVf2. In this study, we used long-read sequencing and in silico gene sequence characterization to identify candidate resistance genes homologous to HcrVf2 and HcrVf1 in Honeycrisp and Antonovka. Previously published chromosome-scale phased assembly of Honeycrisp and a newly assembled phased genome of Antonovka 172670-B were used to identify HcrVf2 and HcrVf1 homologs spanning Vhc1 and Rvi17 loci. In combination with 8 available Malus assemblies, 43 and 46 DNA sequences highly homologous to HcrVf2 and HcrVf1, respectively, were identified on LG 1 and 6, with identity and coverage ranging between 87-95 and 81-95%, respectively. Among these homologs, 2 candidate genes in Antonovka and Honeycrisp haplome A are located in close physical proximity to the scab-resistance marker Ch-Vf1 on LG 1. They showed the highest identity and coverage (95%) of HcrVf2 and only minor changes in the protein motifs. They were identical by state between each other, but not with HcrVf2. This study offers novel genomic resources and insights into the Vhc1 and Rvi17 loci on LG 1 and identifies candidate genes for further resistance characterization.
| S-EPMC10755186 | biostudies-literature
Project description:V. inaequalis causes apple scab disease, the most economically important disease of apples. In this study, we generated a comprehensive RNA-seq transcriptome of V. inaequalis during host colonization of apple, with six in planta time points (12hpi, 24hpi, 2dpi, 3dpi, 5dpi, 7dpi) and one in culture reference (fungus grown on cellophane membranes overlaying potato dextrose agar). Analysis of this transcriptome identified five in planta gene expression clusters or waves corresponding to three specific infection stages: early, mid and mid-late infection of subcuticular biotrophic host-colonization. In our analysis we focus on general fungal nutrition (plant cell wall degrading enzymes and transporters) as well as effectors (proteinaceous effectors and secondary metabolites). Early infection was characterized by the expression of genes that encode plant cell wall-degrading enzymes (PCWDEs) and proteins associated with oxidative stress responses. Mid-late infection was characterized by genes that encode PCWDEs and effector candidates (ECs).
2022-03-14 | GSE198244 | GEO