Wild Apple Research Articles

Apples and Grapes: Thoreau, Latour, and the Land

After decades of studying technoscience as practiced across many disciplines, Bruno Latour turned his attention late in his career almost exclusively to the articulation of critical zones and politics during what he calls the “New Climactic Regime.” Using the same tools he honed throughout his career, the works from Facing Gaia onward try to lay out in clear terms the politics of climate change along with brief forays into possible forms of action. In his last books he presses the specific problem of how to live and attempt to know a specific geographical region without succumbing to isolationism and xenophobia. Many years previous, another irascible and humorous thinker worked similar soils. While Latour’s family has long labored in the Louis Latour vineyards, on the other side of the Atlantic, Henry David Thoreau was seeking wild apples for the long walk home. This essay examines how both thinkers produce a particular vision of a local understanding of place without the oversimplifications of the local/global binary.

EVALUATION OF NORMALIZED DIFFERENCE VEGETATION INDEX IN WILD APPLE POPULATIONS GROWING IN SOUTHEAST MOUNTAIN REGIONS OF KAZAKHSTAN

NDVI is one of the most common vegetation indices for solving various problems of assessing the state of vegetation cover and its dynamics. The purpose of the study was to evaluate the state of wild Sievers apple trees in the territory of Phenological area, Genetic Reserve of Sievers, Tauturgen and Sievers apple reserve (Zhongar-Alatau and Ile-Alatau SNNP) using the NDVI index. The period of study was season’s autumn 2022 and spring 2023. Created interactive maps of the study area with multispectral reconstructions in NDVI formats let us was established the condition of the Sievers apple tree. Which was based on an analysis of the deviation of the NDVI of each tree in the study area from the average index value for the vegetation of the entire type of area. This allowed us to identify the territorial features of the state of the Sievers apple trees and identify degraded trees. The results obtained can be used for the rational management of environmental management by the Zhongar-Alatau SNNP and the Ile-Alatau SNNP.

Multi-Omics Approaches Provide New Insights into the Identification of Putative Fungal Effectors from Valsa mali.

Pathogenic fungi secrete numerous effectors into host cells to manipulate plants' defense mechanisms. Valsa mali, a necrotrophic fungus, severely impacts apple production in China due to the occurrence of Valsa canker. Here, we predicted 210 candidate effector protein (CEP)-encoding genes from V. mali. The transcriptome analysis revealed that 146 CEP-encoding genes were differentially expressed during the infection of the host, Malus sieversii. Proteome analysis showed that 27 CEPs were differentially regulated during the infection stages. Overall, 25 of the 146 differentially expressed CEP-encoding genes were randomly selected to be transiently expressed in Nicotiana benthamiana. Pathogenicity analysis showed that the transient expression of VM1G-05058 suppressed BAX-triggered cell death while the expression of VM1G-10148 and VM1G-00140 caused cell death in N. benthamiana. In conclusion, by using multi-omics analysis, we identified potential effector candidates for further evaluation in vivo. Our results will provide new insights into the investigation of virulent mechanisms of V. mali.

Responses of Nutrients and Bacterial Communities to Temperature and Nitrogen Addition in Rhizosphere Soil for Malus sieversii Seedlings

Responses of Nutrients and Bacterial Communities to Temperature and Nitrogen Addition in Rhizosphere Soil for Malus sieversii Seedlings

Uncovering the antifungal activities of wild apple-associated bacteria against two canker-causing fungi, Cytospora mali and C. parasitica

Cytospora canker has become a devastating disease of apple species worldwide, and in severe cases, it may cause dieback of entire trees. The aim of this study was to characterize the diversity of cultivable bacteria from the wild apple microbiota and to determine their antifungal ability against the canker-causing pathogenic fungi Cytospora mali and C. parasitica. Five bacterial strains belonging to the species Bacillus amyloliquefaciens, B. atrophaeus, B. methylotrophicus, B. mojavensis, and Pseudomonas synxantha showed strong antagonistic effects against pathogenic fungi. Therefore, since the abovementioned Bacillus species produce known antifungal compounds, we characterized the antifungal compounds produced by Ps. synxantha. Bacteria grown on nutritional liquid medium were dehydrated, and the active compound from the crude extract was isolated and analysed via a range of chromatographic processes. High-performance liquid chromatography, mass spectrometry, and nuclear magnetic resonance analyses revealed a bioactive antifungal compound, phenazine-1-carboxylic acid (PCA). The minimum inhibitory concentration (MIC) demonstrated that PCA inhibited mycelial growth, with a MIC of 10 mg mL−1. The results suggested that PCA could be used as a potential compound to control C. mali and C. malicola, and it is a potential alternative for postharvest control of canker disease.

DIA-Based Quantitative Proteomics in the Flower Buds of Two Malus sieversii (Ledeb.) M. Roem Subtypes at Different Overwintering Stages.

Malus sieversii is considered the ancestor of the modern cultivated apple, with a high value for apple tolerance breeding. Despite studies on the temperature adaptability of M. sieversii carried out at a physiological response and the genome level, information on the proteome changes of M. sieversii during dormancy is limited, especially about the M. sieversii subtypes. In this study, a DIA-based approach was employed to screen and identify differential proteins involved in three overwintering periods of flower buds in two M. sieversii subtypes (Malus sieversii f. luteolus, GL; Malus sieversii f. aromaticus, HC) with different overwintering adaptabilities. The proteomic analysis revealed that the number of the down-regulated differential expression proteins (DEPs) was obviously higher than that of the up-regulated DEPs in the HC vs. GL groups, especially at the dormancy stage and dormancy-release stage. Through functional classification of those DEPs, the majority of the DEPs in the HC vs. GL groups were associated with protein processing in the endoplasmic reticulum, oxidative phosphorylation, starch and sucrose metabolism and ribosomes. Through WGCNA analysis, tricarboxylic acid cycle and pyruvate metabolism were highly correlated with the overwintering stages; oxidative phosphorylation and starch and sucrose metabolism were highly correlated with the Malus sieversii subtypes. This result suggests that the down-regulation of DEPs, which are predominantly enriched in these pathways, could potentially contribute to the lower cold tolerance observed in HC during overwintering stage.

Host-induced gene silencing in wild apple germplasm Malus hupehensis confers resistance to the fungal pathogen Botryosphaeria dothidea.

Host-induced gene silencing (HIGS) is an inherent mechanism of plant resistance to fungal pathogens, resulting from cross-kingdom RNA interference (RNAi) mediated by small RNAs (sRNAs) delivered from plants into invading fungi. Introducing artificial sRNA precursors into crops can trigger HIGS of selected fungal genes, and thus has potential applications in agricultural disease control. To investigate the HIGS of apple (Malus sp.) during the interaction with Botryosphaeria dothidea, the pathogenic fungus causing apple ring rot disease, we evaluated whether apple miRNAs can be transported into and target genes in B. dothidea. Indeed, miR159a from Malus hupehensis, a wild apple germplasm with B. dothidea resistance, silenced the fungal sugar transporter gene BdSTP. The accumulation of miR159a in extracellular vesicles (EVs) of both infected M. hupehensis and invading B. dothidea suggests that this miRNA of the host is transported into the fungus via the EV pathway. Knockout of BdSTP caused defects in fungal growth and proliferation, whereas knockin of a miR159a-insensitive version of BdSTP resulted in increased pathogenicity. Inhibition of miR159a in M. hupehensis substantially enhanced plant sensitivity to B. dothidea, indicating miR159a-mediated HIGS against BdSTP being integral to apple immunity. Introducing artificial sRNA precursors targeting BdSTP and BdALS, an acetolactate synthase gene, into M. hupehensis revealed that double-stranded RNAs were more potent than engineered MIRNAs in triggering HIGS alternative to those natural of apple and inhibiting infection. These results provide preliminary evidence for cross-kingdom RNAi in the apple-B. dothidea interaction and establish HIGS as a potential disease control strategy in apple.

Multi-omics analysis reveals the biosynthesis of flavonoids during the browning process of Malus sieversii explants.

Malus sieversii is a precious apple germplasm resource. Browning of explants is one of the most important factors limiting the survival rate of plant tissue culture. In order to explore the molecular mechanism of the browning degree of different strains of Malus sieversii, we compared the dynamic changes of Malus sieversii and Malus robusta Rehd. during the whole browning process using a multi-group method. A total of 44 048 differentially expressed genes (DEGs) were identified by transcriptome analysis on the DNBSEQ-T7 sequencing platform. KEGG enrichment analysis showed that the DEGs were significantly enriched in the flavonoid biosynthesis pathway. In addition, metabonomic analysis showed that (-)-epicatechin, astragalin, chrysin, irigenin, isoquercitrin, naringenin, neobavaisoflavone and prunin exhibited different degrees of free radical scavenging ability in the tissue culture browning process, and their accumulation in different varieties led to differences in the browning degree among varieties. Comprehensive transcriptome and metabonomics analysis of the data related to flavonoid biosynthesis showed that PAL, 4CL, F3H, CYP73A, CHS, CHI, ANS, DFR and PGT1 were the key genes for flavonoid accumulation during browning. In addition, WGCNA analysis revealed a strong correlation between the known flavonoid structure genes and the selected transcriptional genes. Protein interaction predictions demonstrated that 19 transcription factors (7 MYBs and 12 bHLHs) and 8 flavonoid structural genes had targeted relationships. The results show that the interspecific differential expression of flavonoid genes is the key influencing factor of the difference in browning degree between Malus sieversii and Malus robusta Rehd., providing a theoretical basis for further study on the regulation of flavonoid biosynthesis.

An overview of the red-fleshed apple: History and its importance for horticulturists, gardeners, nurserymen, and consumers

The present review summarizes the information on the botany, breeding, genetic features, cultivation, and nutraceutical values of red-fleshed apples. Malus sieversii var. niedzwetzkyana or Niedzwetzky’s apple became widely known after the publication of Georg Dieck in the last XIX century. It is characterized by anthocyanin coloration of all organs. Another source of red flesh is the ancient variety ‘Surprise’, which differs from the Niedzwetzky’s apple by a mutation in another gene. These two mutated genes, MYB10 and MYB110a, are located on chromosomes 9 and 17, respectively. Their expression correlated with the anthocyanin accumulation. In type 1 red-fleshed apples, which belong to the Niedzwetzky’s apple progeny, the transcription factor MYB10 confers extensive anthocyanin accumulation in fruit flesh and skin, flowers, leaves, and stems. In type 2 red-fleshed apples, the ‘Surprise’ progeny, only the flesh is red, determined by the transcription factor MYB110а. A new combination Malus domestica f. niedzwetzkyana comb. nov. has been proposed for orchard apples, originated from Niedzwetzky’s apple. The apple cultivars which are progeny of Niedzwetzky’s apple and ‘Surprise’ apple can be placed to Malus Niedzwetzkyana Group and Malus Surprise Group, respectively. All red-fleshed cultivars of orchard apple can be grouped together into Malus domestica Red Flesh Group. Many dozens of new ornamental apple trees have been developed for of European and North American conditions, including the most famous red-flowered centennial apple varieties such ‘Aldenhamensis’, ‘Lemoinei’, ‘Makamik’, and ‘Oekonomierat Echtermeyer’. Rootstocks ‘MB’, ‘PB9’, ‘54-118’, ‘62-396’ and others have become popular in nurseries for the propagation of dwarf and semi-dwarf apple trees thanks to their red leaves, which are useful when removing scion shoots from budded plants. In the F3-F4 and next generation, the new high-quality red-fleshed cultivars have been developed by crossing both Niedzwetzky’s apple and ‘Surprise’ apple with the best orchard apple varieties. Marker-assisted breeding shows great promise for accelerating the development of new red-fleshed cultivars with outstanding traits. The use of the Redlove®, Red Moon®, Kissabel®, and Lucy™ apples brands will ensure the red-fleshed apples’ best path to the consumer as well as the fruit quality and production volume of these novelties. Increasing the consumption of red-fleshed apples is essential for a healthy diet.

ҚАЗАҚСТАННЫҢ ЖАБАЙЫ АЛМА ОРМАНДАРЫНДА БАКТЕРИЯЛЫҚ КҮЙІКТІҢ ТАРАЛУЫН БАҒАЛАУ

Erwinia amylovora is a dangerous pathogen that causes fire blight in fruit trees. As this pathogen has started to spread in the territory of Kazakhstan, it poses a significant threat to cultivated and wild apple (Malus sieversii) forests. Currently there is no effective treatment for widespread types of fire blight, it can be prevented only by early diagnosis. Although much research has focused on the detection of fire blight in cultivated apple orchards, little attention has been paid to controlling wild apple populations. Therefore, a comprehensive four-year monitoring study was conducted in four protected areas of Kazakhstan to determine the spread of fire blight on wild apple trees. During several years of inspections, Malus sieversii trees showed no obvious signs of fire blight. These observations were further confirmed by lateral flow immunochromatography as well as by conventional and real-time polymerase chain reaction analysis performed on asymptomatic samples. The results of this study are of great importance for nature protection, providing invaluable information about the current state of fire blight in wild apple forests of Kazakhstan. Therefore, these data provide a basis for formulating science-based recommendations to government agencies to take proactive measures aimed at limiting the spread of fire blight in these ecologically important ecosystems.

ДОМИНИРУЮЩИЕ ВИДЫ НАСЕКОМЫХ-ВРЕДИТЕЛЕЙ, ПОВРЕЖДАЮЩИЕ ДИКОРАСТУЩИЕ ПОПУЛЯЦИИ ЯБЛОНИ СИВЕРСА (MALUS SIEVERSII) В ИЛЕЙСКОМ АЛАТАУ

The article is devoted to the problems of conservation of wild populations of the Sievers apple tree (Malus sieversii) in Kazakhstan, which are of global importance as a natural genetic basis for the maintenance and production of apples worldwide. Unfortunately, over the past half century, the area of growth of wild populations of this type of apple tree has sharply decreased, so the issues of preserving apple forests require special attention. One of the main threats to the existence of wild populations of the Sievers apple tree in the last 20 years has become insect pests that cause enormous damage to natural populations. In this regard, the purpose of the publication is to determine the degree of damage to the Sievers apple tree by three main pests (Yponomeuta malinella Zell., Archips rosana L., Cacoecia crataegana Hb.) in the Iley Alatau in 2018, 2019. A map of the distribution and influence of the apple ermine moth (Yponomeuta malinella Zell.), roseate leaf roller (Archips rosana L.), hawthorn leaf roller (Cacoecia crataegana Hb.) on the territory of the Ile-Alatau GNPP is also given.

Hemijski sastav infuzije divlje jabuke (Malus sylvestris (L.) Mill.)

Wild apples leaves are under-utilized biomaterial, containing various bioactive compounds. The aim of this work was to determine the components and mineral composition of the wild apple leaf infusion. The leaves originated from Svrljig, Nišava District, Southern Serbia. The screening of bioactive components in the infusion was performed by the UHPLC-DAD-MS/MS method, while its mineral content was analyzed by the ICP-OES method. The results indicated the presence of quercetin, isoquercetin, hyperoside, rutin, citric and quinic acids, protocatechuic acid, 3-O-p-coumaroylquinic acid, chlorogenic acid, procyanidin B2, phloretin and phloretin-pentosyl-hexoside, while the most abundant elements were Ca, K, Mg and Na. Therefore, wild apple leaves may be utilized for isolation of polyphenolic antioxidants and minerals and production of extracts with antioxidant activity.

First Report of Diplodia intermedia Causing Canker and Dieback Diseases on Apple Trees in Canada.

A dieback of apple trees (Malus domestica (Suckow) Borkh.) associated with cankers was observed in commercial orchards in southwestern Ontario, Canada, in 2019. Fifteen 2 to 10-year-old symptomatic trees were collected from three orchards exhibiting up to 37% disease incidence. Small sections of diseased wood (1 cm long) were surface sterilized with 70% ethanol for 30 sec and 1% NaClO for 20 min, rinsed thrice in sterile water, placed on 2% PDA (Difco) amended with kanamycin (50 mg liter-1), and incubated at 22°C for 5 days in the dark (Ilyukhin et al. 2023). Fungal colonies that were consistently isolated were hyphal-tipped, transferred to individual PDA plates and incubated at 22°C for 7 days in the dark. Purified isolates with same characteristics were classed into morphotypes. One morphotype was initially white and turned dark olivaceous with dense aerial mycelium. Pycnidia were produced on pine needles on PDA (Fig. S2) after incubation at 22°C for 17 days in the dark. Conidia were brown, aseptate, ovoid, and measured 27.9 to 31.3 μm x 12.1 to 14.2 μm (mean ± S.D. of 15 conidia = 29.9 ± 0.9 μm × 13.2 ± 0.6 μm), the typical morphology of a Diplodia sp. (Phillips et al. 2012). Genomic DNA was extracted from a 7-day-old culture of a representative isolate M45-28, using the Plant/Fungi DNA Isolation Kit (Norgen Biotech, Canada). The internal transcribed spacer (ITS), translation elongation factor 1-α (EF1-α) and β-tubulin gene regions were amplified and sequenced with primers ITS1/ITS4, EF1-728F/EF1-986R and Bt2a/Bt2b and deposited in GenBank with accession numbers MZ970605, MZ995430 and MZ995431, respectively. Based on the sequence, the fungus was identified as Diplodia intermedia A.J.L. Phillips et al. and matched isolates from different hosts and countries (ITS: 100%, MG220378; EF1-α: 100%, MG220385; β-tubulin: 99.24%, MT592502). The maximum likelihood-based phylogenetic analysis of ITS, EF1-α and β-tubulin concatenated sequences was performed using IQ-Tree 2.2.2.7 (Minh et al. 2020). M45-28 was clustered with high bootstrap support values with D. intermedia isolates from the Westerdijk Fungal Biodiversity Institute collection, including the ex-holotype (CBS 124462) (Fig. S1). A living culture of M45-28 was deposited in the Canadian Collection of Fungal Cultures (DAOMC 252253). Pathogenicity assay was conducted by inoculating mycelial plugs from a 7-day-old culture of M45-28 into wounds made on the trunk of 5 eight-month-old potted healthy 'Royal Gala' apple seedlings. Five control seedlings were inoculated with sterile plugs. Canker symptoms appeared 15 days after inoculation, spread around, up and down the main stem from the inoculation point, and by 7 weeks the upper portion of the seedling was dead (Fig. S2). Diplodia intermedia was re-isolated from all inoculated seedlings and species identity was confirmed by sequencing as described above, fulfilling Koch's postulates. Control seedlings remained symptomless and the fungus was not isolated from the wood. Diplodia intermedia was reported to cause cankers on apple in Uruguay (Delgado-Cerrone et al. 2016), wild apple (Malus sylvestris) in Portugal (Phillips et al. 2012), grapevines in France (Comont et al. 2016) and forest trees in Iran (Kazemzadeh Chakusary et al. 2019). To the best of our knowledge, this is the first report of D. intermedia causing canker and dieback diseases on apple trees in Canada. Further studies are required to better understand the epidemiology involved in the dynamic spread of the disease in order to recommend an adequate phytosanitary program for its control.

Metabolomic Analysis of the Effect of Freezing on Leaves of Malus sieversii (Ledeb.) M.Roem. Histoculture Seedlings.

Malus sieversii (Ledeb.) M.Roem. is the ancestor of cultivated apples, and is an excellent germplasm resource with high resistance to cold. Artificial refrigerators were used to simulate the low temperature of -3 °C to treat Malus sieversii (Ledeb.) M.Roem. histoculture seedlings. Observations were performed to find the effects of freezing stress on the status of open or closed stomata, photosystems, and detection of metabolomic products in leaves of Malus sieversii (Ledeb.) M.Roem. histoculture seedlings. The percentage of closed stomata in the Malus sieversii (Ledeb.) M.Roem. histoculture seedlings increased, the maximum fluorescence (Fm') excited by a strong light (saturating pulse) was weakened relative to the real-time fluorescence in its vicinity, and the quantum yield of unregulated energy dissipation was increased in PSII under freezing stress. The metabolites in the leaves of the Malus sieversii (Ledeb. M.Roem.) histoculture seedlings were analyzed by ultra-performance liquid chromatography-tandem mass spectrometry using CK, T12h, T36 h, and HF24h. Results demonstrated that cold stress in the Malus sieversii (Ledeb.) M.Roem. histoculture seedlings led to wilting, leaf stomatal closure, and photosystem damage. There were 1020 metabolites identified as lipids (10.2%), nucleotides and their derivatives (5.2%), phenolic acids (19.12%), flavonoids (24.51%), amino acids and their derivatives (7.75%), alkaloids (5.39%), terpenoids (8.24%), lignans (3.04%), organic acids (5.88%), and tannins (0.88%). There were 110 differential metabolites at CKvsT12h, 113 differential metabolites at CKvsT36h, 87 differential metabolites at T12hvsT36h, 128 differential metabolites at CKvsHF24h, 121 differential metabolites at T12hvsHF24h, and 152 differential metabolites at T36hvsHF24h. The differential metabolites in the leaves of the Malus sieversii (Ledeb.) M.Roem. seedlings grown under low-temperature stress mainly involved glycolysis, amino acid metabolism, lipid metabolism, pyrimidine metabolism, purine metabolism, and secondary metabolite metabolism. The Malus sieversii (Ledeb.) M.Roem. seedlings responded to the freezing stress by coordinating with each other through these metabolic pathways. The metabolic network of the leaves of the Malus sieversii (Ledeb.) M.Roem. histoculture seedlings under low temperature stress was also proposed based on the above pathways to deepen understanding of the response of metabolites of Malus sieversii (Ledeb.) M.Roem. to low-temperature stress and to lay a theoretical foundation for the development and utilization of Malus sieversii (Ledeb.) M.Roem. cultivation resources.

Evaluation of the Potential Seed Dispersal Effectiveness of Malus sieversii (Lebed.) M. Roem. by Cattle

The success of plant reproduction is highly dependent on effective seed dispersal. This study aimed to evaluate the potential seed dispersal effectiveness of cattle for Malus sieversii. The impact of cattle on the dispersal quantity and dispersal quality of M. sieversii seeds was explored based on camera trapping, GPS tracking, and germination trials. The results showed that, on average, cattle visited M. sieversii trees 477.33 times during a two-month observation period. Out of these visits, 315 were specifically for fruit removal. The fruit removal rate per cattle visit was as high as 96.67%. Additionally, cattle were able to disperse M. sieversii seeds up to a maximum distance of 533.67 m, with an average dispersal distance of 134.62 m. The average distance of cattle movement was recorded as 176.95 m/h, with peak activity observed during 11:00–13:00 and 19:00–21:00. The germination rate of M. sieversii seeds that passed through the digestive tract of cattle was significantly higher than that of control seeds. Finally, the emergence rate and survival rate of seeds dispersed by cattle to forest edges and gaps were significantly higher than those dispersed to understory. These findings suggest that cattle can serve as effective long-distance dispersers of M. sieversii seeds and may play a crucial role in the regeneration and expansion of M. sieversii populations in the Ili Botanical Garden.

An efficient screening system of disease-resistant genes from wild apple, Malus sieversii in response to Valsa mali pathogenic fungus

For molecular breeding of future apples, wild apple (Malus sieversii), the primary progenitor of domesticated apples, provides abundant genetic diversity and disease-resistance traits. Valsa canker (caused by the fungal pathogen Valsa mali) poses a major threat to wild apple population as well as to cultivated apple production in China. In the present study, we developed an efficient system for screening disease-resistant genes of M. sieversii in response to V. mali. An optimal agrobacterium-mediated transient transformation of M. sieversii was first used to manipulate in situ the expression of candidate genes. After that, the pathogen V. mali was inoculated on transformed leaves and stems, and 3 additional methods for slower disease courses were developed for V. mali inoculation. To identify the resistant genes, a series of experiments were performed including morphological (incidence, lesion area/length, fungal biomass), physiological (H2O2 content, malondialdehyde content), and molecular (Real-time quantitative Polymerase Chain Reaction) approaches. Using the optimized system, we identified two transcription factors with high resistance to V. mali, MsbHLH41 and MsEIL3. Furthermore, 35 and 45 downstream genes of MsbHLH41 and MsEIL3 were identified by screening the V. mali response gene database in M. sieversii, respectively. Overall, these results indicate that the disease-resistant gene screening system has a wide range of applications for identifying resistant genes and exploring their immune regulatory networks.

Quantitative Trait Locus Mapping for Fire Blight Resistance in an F2 Population of Malus fusca MAL0045 Uncovers Novel Resistance Loci.

Several fire blight resistance loci in Malus genotypes map on different linkage groups (LGs) representing chromosomes of the domesticated apple. Prior genetics studies primarily focused on F1 populations. A strong resistance quantitative trait locus (QTL) explained up to 66% of phenotypic variance in an F1 progeny derived from crossing the highly resistant wild apple genotype Malus fusca MAL0045 and the highly susceptible apple cultivar 'Idared', which was previously mapped on LG10 (Mfu10) of MAL0045. Strains of the causative bacterial pathogen Erwinia amylovora, notably those that show a single nucleotide polymorphism in the avrRpt2EA effector protein sequence at position 156 (e.g., Ea3049), are more virulent and overcome some known fire blight resistance donors and their QTLs. However, MAL0045 is resistant to Ea3049 and Mfu10 is not overcome, but most of the F1 progeny were highly susceptible to this strain. This phenomenon led to the assumption that other putative resistance factors not segregating in the F1 progeny might be present in the genome of MAL0045. Here, we crossed F1 progeny together to obtain 135 F2 individuals. Facilitated by genotyping-by-sequencing and phenotypic assessments, we identified and mapped two novel resistance QTLs in these F2 individuals on LGs 4 and 15, which were not identified in the F1. To our knowledge, these are the first resistance QTLs mapped in F2 progeny in Malus. In addition, we report that neither MAL0045 nor Mfu10 is broken down by a highly aggressive U.S. strain, LA635, after analyses in the original F1 individuals. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

СРАВНИТЕЛЬНЫЙ МОРФОЛОГО-АНАТОМИЧЕСКИЙ АНАЛИЗ ЦВЕТКОВ ЯБЛОНИ ЯГОДНОЙ И ДОМАШНЕЙ

At the stage of the analysis of scientific literature, the authors revealed the presence of publications characterizing the wide interest of researchers in the new medicinal plant raw apple blossoms of different types and varieties. The data confirming the presence of phenolic substances in the raw materials (coffee, cinnamon, m-coumaric, p-coumaric, ferulic, 4-hydroxybenzoic, salicylic, synaptic, syringic, vanilla and gallic acids) and flavonoid components (apigenin, isoquercitrin, luteolin, quercetin, quercitrin and rutin) were obtained. In the Russian Federation there is a significant stock of both wild and cultivated apple species, among which the domestic apple tree (Malus domestica Borkh.) and the berry apple tree (Malus baccata (L.) Borkh) are of scientific interest. Taking into account the lack of scientific information aimed at standardization of new raw materials, the authors analyzed the external and microscopic signs of apple and berry flowers dried by isothermal drying, as well as frozen. The analysis of external signs was carried out in accordance with the requirements of the OFS.1.5.1.0004.15 Flowers, microdiagnostic analysis was performed according to OFS.1.5.3.0003.15 Technique of microscopic and microchemical research of medicinal plant raw materials and medicinal plant preparations. Morphological features related to the size of flowers and the structure of sepals were revealed during microdiagnostic examination, diagnostic signs common to both species were revealed, as well as specific for each specific species. The general ones include the tortuosity of the epidermis, the type of stomatal apparatus, the presence of essential oil glands, as well as numerous sinuous simple hairs. Also common features are a significant number of calcium oxalate inclusions represented by druses and prismatic crystals. A specific feature of the berry apple tree is the presence of glands on multicellular legs along the edge of the stipule. The results of the work can be displayed in the relevant sections of the regulatory documentation being developed

Screening of rhizosphere nitrogen fixing, phosphorus and potassium solubilizing bacteria of Malus sieversii (Ldb.) Roem. and the effect on apple growth

Nitrogen, phosphorus and potassium inorganic fertilizers are commonly used when growing apples, but their excessive application has resulted in a decline in soil fertility and therefore an inability to maintain sustainable cultivation systems. It is possible to compensate for this with biofertilizers. Nitrogen-fixing, phosphorus solubilizing, and potassium solubilizing bacteria are biofertilizers with a broad range of possible uses. In this study, beneficial microorganisms were screened from the rhizosphere soil of the apple tree, Malus sieversii (Ldb.) Roem., which is rich in microbial diversity in natural environments. It was essential to investigate their effects on the growth of apple seedlings. Eight populations of organic phosphorus solubilizing bacteria (56), inorganic phosphorus solubilizing bacteria (13), nitrogen-fixing bacteria (22), and potassium solubilizing bacteria (24) were isolated from eight populations of Xinjiang wild apple rhizosphere in Ili by medium culture. Their morphological characteristics were recorded and their activity was determined. The most active strains were Pseudomonas migulae, Pseudomonas poae, and Pseudomonas extremaustralis, which was determined by physiological and biochemical properties and 16S rDNA sequence analysis. The L16 (45) orthogonal experiment, which used the three strains as testing materials, was created to assess the effects of the strains on apple physiological indicators, soil nutrients, leaf nutrients, and biomass, as well as to identify the ideal combination, concentration, timing, and application method. The results indicated that the peroxidase (POD) and catalase (CAT) activities of apple seedlings increased significantly under the 10 treatment, and the (SOD) activities of the 0 (control) and 1 (inorganic fertilizer only) treatments were significantly lower than the other treatments; soluble sugar, soluble protein and chlorophyll contents increased in all treatments compared to 0 and 1, while malondialdehyde and proline contents increased or decreased compared to 0 and 1; apple seedlings in treatment 10 had the highest soil N, P, and K content, leaf N, P, and K content and biomass were also all highest in treatment 10. In summary, the strains screened for the test can be used as biofertilizers and the optimum application was determined for treatment 10, meaning that the results also provide a theoretical basis for their application in artificially grown orchards.

Effect of Nitric Oxide on Browning of Stem Tip Explants of Malus sieversii

Browning is a major problem in the tissue culture of woody plants. Previous studies have shown that nitric oxide (NO) plays a role in regulating plant responses to stress, but its effect on browning in the tissue culture of Malus remains unclear. This study aimed to investigate the impact of exogenous NO donor sodium nitroprusside (SNP) on the browning of Malus sieversii stem tip explants. The results demonstrated that the addition of 50 μM SNP significantly reduced explant browning. Further analysis revealed that exogenous NO decreased the browning index (BD) and levels of malondialdehyde (MDA), hydrogen peroxide (H2O2), and superoxide anion radical O2−. Additionally, NO treatment increased the activity of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX). NO treatment also enhanced the activity of phenylalanine ammonia lyase (PAL), which contributed to the accumulation of flavonoids and inhibited the activity of polyphenol oxidase (PPO) and peroxidase (POD), which are key enzymes involved in the browning process. Furthermore, 50 μM SNP significantly promoted the accumulation of non-enzymatic antioxidants such as proline (Pro), soluble sugar (SS), and soluble protein (SP). Therefore, the results suggest that NO is able to counteract excessive reactive oxygen species (ROS) damage by enhancing both the enzymatic and non-enzymatic antioxidant systems, resulting in a reduction in browning in stem tip explants. Consequently, an improvement in the in vitro propagation efficiency of Malus sieversii shoot tip explants can be achieved.