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At least 19 recordsLinked to original sources
PubMed2006

Chloroplast diversity in the genus Malus: new insights into the relationship between the European wild apple (Malus sylvestris (L.) Mill.) and the domesticated apple (Malus domestica Borkh.).

To unravel the relationship between the European wild apple, Malus sylvestris (L.) Mill., and its domesticated relative M. domestica Borkh., we studied chloroplast DNA variation in 634 wild and 422 domesticated accessions originating from different regions. Hybridization between M. sylvestris and M. domestica was checked using 10 nuclear microsatellites and a Bayesian assignment approach. This allowed us to identify hybrids and feral plants escaped from cultivation. Sixty-eight genotypes belonging to 12 other wild Malus species, including 20 M. sieversii (Ledeb.) Roem. accessions were also included in the analysis of chloroplast diversity. Marker techniques were developed to type a formerly described duplication and a newly detected transversion in the matK gene. Chloroplast DNA variation was further investigated using PCR-RFLP (Polymerase Chain Reaction-Random Fragment Length Polymorphism), and haplotypes were constructed based on all mutational combinations. A closer relationship than presently accepted between M. sylvestris and M. domestica was established at the cytoplasmic level, with the detection of eight chloroplast haplotypes shared by both species. Hybridization between M. sylvestris and M. domestica was also apparent at the local level with sharing of rare haplotypes among local cultivars and sympatric wild trees. Indications of the use of wild Malus genotypes in the (local) cultivation process of M. domestica and cytoplasmic introgression of chloroplast haplotypes into M. sylvestris from the domesticated apple were found. Only one of the M. sieversii trees studied displayed one of the three main chloroplast haplotypes shared by M. sylvestris and M. domestica. This is surprising as M. sieversii has formerly been described as the main maternal progenitor of the domesticated apple. This study hereby reopens the exciting discussion on the origin of M. domestica.

Base Sequence↗
PubMed2005

The Vh8 locus of a new gene-for-gene interaction between Venturia inaequalis and the wild apple Malus sieversii is closely linked to the Vh2 locus in Malus pumila R12740-7A.

The wild apple (Malus sieversii) is a large-fruited species from Central Asia, which is used as a source of scab resistance in cultivar breeding. Phytopathological tests with races of Venturia inaequalis were performed to differentiate scab-resistance genes in Malus as well as an avirulence gene in the pathogen. A novel gene-for-gene interaction between V. inaequalis and Malus was identified. The locus of the scab-resistance gene Vh8 is linked with, or possibly allelic to, that of the Vh2 gene in Malus pumila Russian apple R12740-7A, at the lower end of linkage group 2 of Malus. Race 8 isolate NZ188B.2 is compatible with Vh8, suggesting the loss or modification of the complementary AvrVh8 gene, while isolate 1639 overcomes both Vh2 and Vh8, but is incompatible with at least one other gene not detected by any of the other race isolates tested. Our research is the first to differentiate scab-resistance genes in a putative gene cluster in apple with the aid of races of V. inaequalis.

Ascomycota↗
PubMed2001

Genomic DNA sequences encoding Malus x domestica Borkh. "Akane", "Delicious" and Malus transitoria S-RNases.

All S-RNases in apple contained one intron at the same location within the hypervariable region. They code for 225-228 amino acids, however, the length of introns is variable and divided into three groups. The intron sequences of some S-RNases within the same group showed an extremely high similarity as well as their coding sequences, suggesting that they were generated from the same origin.

Evolution, Molecular↗
PubMed2006

Expression of MaMAPK gene in seedlings of Malus L. under water stress.

Seedlings of three species of Malus were used to study the expression of mitogen-activated protein kinase (MAPK) in response to water stress: Malus hupehensis, a drought-sensitive species; Malus sieversii, a drought-tolerant species; and Malus micromalus, a middle type. Results showed that Malus MAPK (MaMAPK, GenBank accession No. AF435805) was expressed in both roots and leaves of seedlings of the three Malus species treated with 20% polyethylene glycol for different time periods. Expression levels peaked at 1.5 h after treatment with polyethylene glycol, then decreased to their lowest levels. Liquid kinase assays indicated that the dynamic changes of MAPK activity were very similar to those of the relative expression of MaMAPK mRNA. However, the peak of the former occurred slightly behind the latter. It was noticed that, although the kinase activity decreased after the peak, it was still higher than that of the control during the whole time period. These results suggested that MaMAPK was regulated not only by water stress at the transcription level, but also by phosphorylation and dephosphorylation at the protein level. In addition, of these three apple species, the highest MAPK activity and MaMAPK expression level was found in M. sieversii, followed by M. micromalus and M. hupehensis, suggesting that MAPK might be correlated with drought tolerance in these three species. The different expression levels might be one of the molecular mechanisms of the different drought tolerances in Malus.

Disasters↗
PubMed2005

Variation in nuclear DNA content in Malus species and cultivated apples.

The nuclear DNA content for a group of 40 Malus species and hybrids has been estimated using flow cytometry. Estimates of nuclear DNA content for this germplasm collection range from 1.45 pg for Malus fusca (diploid) to 2.57 pg for Malus ioensis (triploid). Among diploids, the nuclear (2C) DNA ranges from 1.45 pg for M. fusca to 1.68 pg for Malus transitoria. Among triploids, the nuclear (3C) DNA content ranges from 2.37 pg / 3C for Malus sikkimensis to 2.57 pg / 3C for M. ioensis. Given the complexity of the apple genome and its suggested allopolyploid origin, the results obtained in this study confirm earlier reports that polyploids can easily withstand the loss of a certain amount of DNA, and that there is a slight tendency towards diminished haploid nuclear DNA content with increased polyploidy.

Cell Nucleus↗
PubMed2026

Introgression shapes the genomic conflict landscape of Malus, providing evidence for a reticulate backbone in a woody crop lineage.

Phylogenomic discordance is widespread across plants, but its evolutionary significance is often obscured when conflict is treated primarily as analytical noise rather than as evidence of underlying processes. In woody lineages in particular, incomplete lineage sorting, introgression, and genome duplication can interact over long timescales to produce complex genomic histories that are not adequately summarized by a strictly bifurcating tree. Here, we use Malus as a model woody genus to investigate how these processes structure conflict across a genus-scale, accession-based phylogenomic framework. Using broad taxon sampling, hundreds of nuclear loci, plastid genomes, and genome-wide SNP summaries, we reconstruct a robust nuclear backbone for sampled Malus lineages and evaluate where discordance is concentrated and which processes best explain it. Nuclear analyses resolve eight major clades, whereas conflict is non-random and localized to recurrent hotspots rather than evenly distributed across the tree. Cytonuclear discordance is similarly concentrated, especially around Clade H, represented by sampled accessions of M. tschonoskii, where localized plastid-nuclear disagreement is consistent with candidate plastid capture or organellar introgression. Multiple complementary analyses further indicate that the strongest conflict is not explained by ILS alone, but instead reflects lineage-structured introgression, while polyploid complexes represent additional localized sources of evolutionary complexity. Together, these results provide evidence for a reticulate genomic backbone in Malus and show how integrating nuclear, plastid, and genome-wide conflict analyses can help distinguish background discordance from process-specific signals in woody plant radiations. Several lineage-level reticulation hypotheses identified here should now be tested with broader population-level sampling and curated reference accessions.

Malus↗
PubMedDate not supplied

Detection of isorhamnetin glycosides in extracts of apples (Malus domestica cv. "Brettacher") by HPLC-PDA and HPLC-APCI-MS/MS.

Extracts of apple fruits (Malus domestica cv. "Brettacher") were analysed by HPLC with photodiode array detection. An unknown peak was monitored displaying the same retention time as isorhamnetin 3-O-glucoside. Preliminary identification of the isorhamnetin aglycone was performed by comparison of UV spectral data of the unknown compound with a reference substance. Using atmospheric pressure chemical ionisation mass spectrometry in the negative ion mode, the presence of an isorhamnetin glycoside was supported by loss of 162 amu from the pseudomolecular ion (m/z 477). MS2 product ion analysis of the parent ion m/z 477 provided a fragmentation pattern identical to the reference. Collision-induced dissociation of the aglycone (m/z 315) in the MS3 product ion analysis allowed the differentiation of rhamnetin and isorhamnetin, and unambiguous assignment by comparison with standard compounds. A second isorhamnetin glycoside eluting prior to the glucoside was tentatively identified as isorhamnetin 3-O-galactoside. To the best of our knowledge, this is the first report of isorhamnetin glycosides in apple fruit extracts. Results are discussed with respect to chemotaxonomic relevance within the genera Malus and Pyrus, and especially in consideration of the control of the authenticity of apple products.

Atmospheric Pressure↗
PubMed2003

Molecular cloning, substrate specificity of the functionally expressed dihydroflavonol 4-reductases from Malus domestica and Pyrus communis cultivars and the consequences for flavonoid metabolism.

Treatment with the dioxygenase inhibitor prohexadione-Ca leads to major changes in the flavonoid metabolism of apple (Malus domestica) and pear (Pyrus communis) leaves. Accumulation of unusual 3-deoxyflavonoids is observed, which have been linked to an enhanced resistance toward fire blight. The committed step in this pathway is the reduction of flavanones. Crude extracts from leaves are able to perform this reaction. There was previous evidence that DFR enzymes of certain plants possess additional flavanone 4-reductase (FNR) activity. Such an FNR activity of DFR enzymes is proved here by heterologous expression of the enzymes. The heterologously expressed DFR/FNR enzymes of Malus and Pyrus possess distinct differences in substrate specificities despite only minor differences of the amino acid sequences. Kinetic studies showed that dihydroflavonols generally are the preferred substrates. However, with the observed substrate specificities the occurrence of 3-deoxyflavonoids in vivo after application of prohexadione-Ca can be explained.

Alcohol Oxidoreductases↗
PubMed2003

Genetic variation in the endangered wild apple (Malus sylvestris (L.) Mill.) in Belgium as revealed by amplified fragment length polymorphism and microsatellite markers.

The genetic variation within and between wild apple samples (Malus sylvestris) and cultivated apple trees was investigated with amplified fragment length polymorphisms (AFLP) and microsatellite markers to develop a conservation genetics programme for the endangered wild apple in Belgium. In total, 76 putative wild apples (originating from Belgium and Germany), six presumed hybrids and 39 cultivars were typed at 12 simple sequence repeats (SSR) and 139 amplified fragment length polymorphism (AFLP) loci. Principal co-ordinate analysis and a model-based clustering method classified the apples into three major gene pools: wild Malus sylvestris genotypes, edible cultivars and ornamental cultivars. All presumed hybrids and two individuals (one Belgian, one German) sampled as M. sylvestris were assigned completely to the edible cultivar gene pool, revealing that cultivated genotypes are present in the wild. However, gene flow between wild and cultivated gene pools is shown to be almost absent, with only three genotypes that showed evidence of admixture between the wild and edible cultivar gene pools. Wild apples sampled in Belgium and Germany constitute gene pools that are clearly differentiated from cultivars and although some geographical pattern of genetic differentiation among wild apple populations exists, most variation is concentrated within samples. Concordant conclusions were obtained from AFLP and SSR markers, which showed highly significant correlations in both among-genotypes and among-samples genetic distances.

Belgium↗
PubMed2002

[Phylogeny of the Malus (apple tree) species, inferred from its morphological traits and molecular DNA analysis].

Some debated issues of the genus Malus (apple) taxonomy were examined using a variety of species from the collection of the Maikop Experimental Station, Vavilon Research Institute of Plant Industry (Krasnodar krai). Phylogenetic relationships among these species were studied using traditional analysis of morphological traits, RAPD, and complete sequencing of the 5'-internal transcribed spacer (ITS1), 5.8S rRNA, 3'-internal transcribed spacer (ITS2) (constituting a cluster of the rRNA genes), and the terminal fragment of the matK gene encoding chloroplast maturase. The results showed that the Sorbomalus section was polyphyletic; the American apple M. fusca was closely related to the species contributing to the East Asian center of the genus origin, and the American species M. angustifolia, M. coronaria, and M. ioensis were closely related to the M. trilobata relict species, whose assignment to the genus Malus is debated by some authors. Molecular analysis of the species relationships showed that the Middle Asian apple M. sieversii is the species from which apple domestication started.

Asia↗
PubMed2003

[Optimum soil water supply range of Malus pumila].

By means of the determination of net photosynthetic rate and transpiration rate of the leaves of seven-year field and two-year spotted Malus pumila (Goldspur) under different soil water contents and illumination and calculation of water use efficiency (WUE), the optimum soil water supply range of Malus pumila was determined. The results showed that because photosynthetic advantageous radiation (PAR) and soil water content (SWC) decided the value of photosynthetic rate and transpiration rate of Goldspur, thus they influenced the value of WUE. The response of WUE to illumination had relations with soil water. When SWC was 10% (50% of field capacity-FC) or so, the maximum of WUE was the highest value among all the soil water treatment and reached about 230 mumolCO2.g-1H2O. When the water supply was adequate (SWC > 15%), the maximum was only 160 mumolCO2.g-1H2O or so, the difference between each SWC level was not obvious and simulated curve fundamentally overlapped, although WUE decreased slowly after reached the maximum. The variation of WUE with SWC had relations with illumination. WUE was the highest while PAR was in the range of 500-1,000 mumol.m-2.s-1). Because the state of soil water decided the values of stomatic resistance (RS) and leaf water potential, RS and psi 1 also had influence on the changes of WUE. When RS and psi 1 were respectively 2.0 s.cm-1 and -3.0 MPa, WUE was the highest, but Pn was relatively low, which was not good to the normal growth and fruitage of trees. From the overall consideration of WUE, Pn and Tr, the scopes of RS and psi 1 were 2-6 s.cm-1 and -2.1 approximately -1.65 MPa, respectively, which not only guaranteed the normal photosynthesis of Goldspur, but also benefited the increase of WUE. The scope of the corresponding SWC was 11%-15%, which was equal to 55%-75% of FC and this scope could be used as theoretical index of field water supply for Goldspur.

Light↗
PubMed2004

[Indole butyric acid activates Ca2+-ATPase in Malus hupehensis Rhed. roots by protein phosphorylation].

The effect of IBA on protein kinase and Ca(2+)-ATPase activity of Malus hupehensis Rhed. roots were studied by adding 3, 3', 4', 5, 7-pentahydroxyflavone (quercetin), a protein kinase inhibitor, and IBA into the Hagland nutrient solution at different time. The results showed that membrane protein phosphorylation in roots occurred mainly on the serine residues. After treatment of Malus hupehensis Rhed.roots with 100 mumol/L IBA, the activity of protein kinase and Ca(2+)-ATPase increased several dozens of times in 2-3 h and then decreased rapidly after they reached the vertex. The protein kinase activity changes earlier than that of Ca(2+)-ATPase. Quercetin not only inhibits the protein kinase activity, but also weakens the activation of Ca(2+)-ATPase by IBA markedly. It is suggested that Ca(2+)-ATPase may be a member of IBA signal transduction in M. hupehensis roots and IBA activates Ca(2+)-ATPase activity through protein phosphorylation.

Calcium-Transporting ATPases↗
PubMed2006

[The effect of exogenous H2O2 on mitochondrial membrane permeability and cell nuclear DNA in roots of Malus hupehensis].

To investigate the changes in mitochondrial permeability transition, DNA degradation and cell death, seedling roots of Malus hupehensis Rehd. were treated directly with exogenous H(2)O(2). The results showed that mitochondrial permeability increased obviously by 0.024% (V/V) H(2)O(2) treatment for 30 min and increased continuously during the time of H(2)O(2) treatment (Fig.1). At the time of mitochondrial permeability increasing, mitochondrial membrane potential (Delta psi m) decreased (Fig.2). In addition, the ratio of Cyt c/a became lower (Fig.3) when mitochondrial permeability increased and Delta psi m decreased. DNA fragments were detected at the 60 min of H(2)O(2) treatment, the number of fragments increased after 60 min of H(2)O(2) treatment (Fig.4). Granular nuclei stained irregularly were evident in root slices stained by acridine orange (Fig.5). This indicates H(2)O(2) can induce programmed cell death by increasing mitochondrial permeability and decreasing Delta psi m in the root of Malus hupehensis Rehd.

Cell Nucleus↗
PubMed2005

Endophytic yeasts and filamentous fungi associated with southern Brazilian apple (Malus domestica) orchards subjected to conventional, integrated or organic cultivation.

Endophytic fungi were isolated from leaves, flowers and fruit of healthy apple trees (Malus domestica , Borkh.) growing in southern Brazilian orchards under three different cultivation systems (conventional, integrated and organic), during two vegetative cycles. The greatest total number of endophytic isolates was obtained from the orchards under organic cultivation when compared to integrated and conventional cultivation systems. Filamentous fungi from the genera Colletotrichum , Xylaria and Botryosphaeria were the most frequent ones and the most representative yeast genera were Sporobolomyces , Rhodotorula , Debaryomyces and Cryptococcus . It is suggested that some isolates may be used as indicators of the different management systems.

Brazil↗
PubMed2004

Inheritance of the Md-ACS1 gene and its relationship to fruit softening in apple ( Malus x domestica Borkh.).

The 1-aminocyclopropane-1-carboxylic acid synthase (ACS) gene is a member of the ACS gene family that is involved in apple ( Malus x domestica Borkh.) fruit ripening. Presence of an allele ( Md-ACS1-2) of this gene is associated with low internal ethylene concentration in some apple cultivars. In this study, inheritance of Md-ACS1 was determined for 50 apple cultivars/advanced selections and 101 F(1) seedlings from five populations. Following this, the softening pattern of apples stored at 20 degrees C for up to 40 days was examined using 35 fruiting cultivars/selections of defined Md-ACS1 status. Md-ACS1 is inherited in a Mendelian fashion and was found to be linked to fruit softening. Maturity season of genotypes also significantly affected fruit softening. Late-season genotypes in the Md- ACS1-2/2 class had the slowest rate of softening, while early-season Md- ACS1-1/1 genotypes had the most rapid softening rate. The implications of these results are discussed in relation to parental selection and breeding for storage ability in apple.

Alleles↗
PubMed2004

Molecular markers linked to the apple scab resistance gene Vbj derived from Malus baccata jackii.

Breeding for scab-resistant apple cultivars by pyramiding several resistance genes in the same genetic background is a promising way to control apple scab caused by the fungus Venturia inaequalis. To achieve this goal, DNA markers linked to the genes of interest are required in order to select seedlings with the desired resistance allele combinations. For several apple scab resistance genes, molecular markers are already available; but until now, none existed for the apple scab resistance gene Vbj originating from the crab apple Malus baccata jackii. Using bulk segregant analysis, three RAPD markers linked to Vbj were first identified. These markers were transformed into more reliable sequence-characterised amplified region (SCAR) markers that proved to be co-dominant. In addition, three SSR markers and one SCAR were identified by comparing homologous linkage groups of existing genetic maps. Discarding plants showing genotype-phenotype incongruence (GPI plants) plants, a linkage map was calculated. Vbj mapped between the markers CH05e03 (SSR) and T6-SCAR, at 0.6 cM from CH05e03 and at 3.9 cM from T6-SCAR. Without the removal of the GPI plants, Vbj was placed 15 cM away from the closest markers. Problems and pitfalls due to GPI plants and the consequences for mapping the resistance gene accurately are discussed. Finally, the usefulness of co-dominant markers for pedigree analysis is also demonstrated.

Ascomycota↗
PubMed2007

Influence of IBA and aphidicolin on DNA synthesis and adventitious root regeneration from Malus 'Jork 9' stem discs.

Adventitious root formation in Malus 'Jork 9' stem discs was studied through temporarily blocking DNA synthesis by application of aphidicolin (AD). Higher number of roots per disc (8.4) after 21 days of cultivation were formed after a 24-h pulse of 15 microM AD, compared to control without AD application (6.7), with significantly more roots (3.7) already appearing at day 7, compared to 1.5 roots on the control. The promotive effect of AD on rooting was lower at 5 microM, while a concentration of 30 microM was slightly inhibitory. Results show that DNA synthesis is effectively blocked by AD, and this blockage is overcome after AD withdrawal. The data indicate that AD treatment influences cell divisions, thereby, might synchronise root initiation. The effects of different treatments with and without AD were studied at the cellular level by visualising DNA replication through BrdU-labelling. BrdU labelling further revealed temporal changes in the competence of the explants to respond to applied IBA. Thus, it is shown that the proportion of replicating nuclei present during 28-32 h is significantly increased in the split IBA treatment (0-4 h and 28-32 h; treatment C3), compared with a single IBA application during 0-8 h (treatment C3.1).

Aphidicolin↗
PubMed2001

Non destructive analysis of the wax layer of apple (Malus domestica Borkh.) by means of confocal laser scanning microscopy.

Confocal laser scanning microscopy (CLSM) was used to non-destructively analyse the changes in the structure and thickness of the cuticle during storage of apples (Malus domestica Borkh.). Interpretation of the confocal images was performed by comparison with scanning electron microscopy and environmental scanning electron microscopy images. The natural reflectance of the wax and the auto-fluorescence of the underlying cells made it possible with CLSM to distinguish the wax from the underlying layers without any pretreatment of the fruit. The thickness of the consecutive layers (wax, cutin, cells) could be estimated from measurements of the reflection and fluorescence intensities as a function of the number of pixels. The mean wax-layer thickness measured in this way amounted to 2.58 microm, 3.41 microm or 4.14 microm for the cultivars Jonagold, Jonagored and Elstar, respectively. Changes in the wax structure and cells of the same important Belgian apple cultivars as mentioned above were monitored during nine months of storage in ultra low oxygen and after exposure to ambient conditions. The changes in the wax ultrastructure and cell morphology are likely related to water losses and specific protection of the apple cultivars against water losses during storage and shelf life.

Fruit↗