Search Results (218)

Repeated drought–rehydration episodes expose perennial fruit trees to alternating stress and recovery phases, while treatment-level averages can obscure genotype-specific response strategies. We evaluated seven biochemical markers in fourteen apple (Malusdomestica Borkh.) genotypes during two consecutive drought–rehydration cycles: proline, malondialdehyde (MDA), total phenolics, total flavonoids, and the activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POX). Both drought cycles increased all measured markers, with the strongest overall response at the end of the second drought cycle (T6). Relative to the control, mean values at T6 increased by 272.4% for proline, 136.4% for MDA, 45.3% for total phenolics, 76.5% for total flavonoids, 109.1% for SOD, 89.0% for CAT, and 117.5% for POX. Genotype-specific log₂(Stress/Control) profiles at the first (T2) and second (T6) drought maxima revealed contrasting combinations of osmotic adjustment, oxidative damage, antioxidant-enzyme activity, and secondary-metabolite accumulation. B11 combined comparatively low MDA induction with strong antioxidant-enzyme responses, whereas HL1282 and HL1579 showed lower proline and MDA induction together with stronger phenolic, flavonoid, and selected enzyme responses. In contrast, ‘Idared’ showed strong proline and MDA induction. The first two principal components explained 75.1% of the total variance. Overall, the results identify distinct genotype-specific biochemical response strategies and show that coordinated marker profiles provide substantially more information than individual biomarkers or treatment averages alone. Full article

Apple (Malus domestica Borkh.) production is increasingly threatened by fungal diseases under conditions of intensive horticulture and ongoing climate change. In southeastern Kazakhstan, symptoms associated with Alternaria spp. have become more frequent in commercial orchards; however, molecularly confirmed data on the pathogen associated with these symptoms remain limited. This study aimed to identify, using multigene molecular phylogenetic analysis, an Alternaria isolate obtained from infected apple leaves and fruits, to confirm its pathogenicity experimentally, and to compare the susceptibility of apple cultivars to this pathogen. For molecular identification, nucleotide sequences of four genetic markers—the ITS region of rDNA, SSU, tef1-α, and RPB2—were obtained by PCR and sequencing. The sequences were compared with reference data from the GenBank database using BLASTn, and phylogenetic relationships were inferred using the maximum likelihood method based on a concatenated dataset of the four loci. The isolate KZ17 clustered within the A. alternata clade, with the broader node uniting this group with A. gossypina and A. longipes receiving a bootstrap value of 78%. A total of 20 fungal isolates were obtained from 112 symptomatic apple leaf and fruit samples. Among them, one representative isolate, KZ17, was selected for multilocus molecular identification and pathogenicity testing. The pathogenicity of isolate KZ17 was confirmed in inoculation experiments on apple microshoots under controlled conditions. Artificial inoculation of detached leaves and ripe fruits of 14 apple cultivars revealed significant cultivar-dependent differences in susceptibility. Lesion diameters ranged from 12.3 ± 0.20 to 19.2 ± 0.35 mm on detached leaves and from 15.0 ± 1.2 to 30.0 ± 2.4 mm on ripe fruits. The least susceptible cultivars were ‘Granny Smith’, ‘Zaman’, and ‘Maksat’, whereas ‘Voskhod’, ‘Saltanat’, and ‘Kamila’ showed the greatest susceptibility. These differences were statistically significant (p < 0.001). This study provides the first multigene-based confirmation of the association of A. alternata with apple leaf and fruit lesions in southeastern Kazakhstan and demonstrates cultivar-dependent differences in susceptibility to this pathogen. These findings contribute to improved pathogen diagnostics, germplasm screening for resistance, and the development of plant protection strategies for commercial apple orchards. Full article

Apple (Malus domestica Borkh.) is a major fruit crop of global economic importance, and China ranks first worldwide in both apple cultivation area and total production. With the large-scale renewal of aging orchards, apple replant disease (ARD) has become increasingly prevalent in major apple-producing regions. ARD is typically characterized by severe growth suppression, impaired root development, increased incidence of soil-borne diseases, and, in severe cases, seedling mortality. These symptoms substantially constrain orchard renewal, limit improvements in fruit yield and quality, and threaten the sustainable development of the apple industry. The etiology of ARD is complex and involves the synergistic interaction of three factors: soil microbial dysbiosis characterized by pathogen enrichment and the depletion of beneficial microorganisms; allelopathic autotoxicity caused by the accumulation of phenolic acids, especially phloridzin; and degraded soil physicochemical properties, including acidification, compaction, and nutrient imbalance. Current management strategies mainly include the use of ARD-tolerant rootstocks, microbial regulation, chemical and physical soil disinfection, and agronomic practices such as crop rotation and organic amendment application. Among these approaches, biological regulation mediated by beneficial rhizosphere and endophytic microorganisms has attracted increasing attention because of its environmental compatibility and sustainability. This review summarizes the occurrence patterns, regional characteristics, core pathogenic mechanisms, and integrated management strategies of ARD, with particular emphasis on the functional roles of rhizosphere and endophytic microbiomes in disease alleviation. The review provides a theoretical basis and practical reference for the development of green, efficient, and sustainable strategies for ARD control and apple orchard management. Full article

Objectives: Within the framework of the European Union’s Submeasure 10.2 for the conservation and sustainable use and development of genetic resources in agriculture, this study aimed to genetically characterize specific apple (Malus domestica Borkh.) varieties from the Abruzzo region (Italy) using SSR (Simple Sequence Repeat) markers. Methods: A total of 67 samples, including 10 reference accessions from a national germplasm collection, were analyzed to assess genetic diversity and varietal traceability. Nine highly polymorphic SSR markers were selected based on a literature review and applied to DNA extracted from leaf tissues. Results: Molecular analyses, including PCR amplification and capillary electrophoresis, revealed seven genetic groups with identical profiles and 15 individuals with unique genetic fingerprints, representing approximately 22% of the dataset. Statistical analyses using R Studio (PAST and LEA) confirmed high genetic diversity (mean PIC = 0.81; mean He = 0.83) and identified two major genetic clusters, with evidence of admixed ancestry in some accessions. Conclusions: These findings highlight discrepancies between declared and actual varietal identities, underscore the value of genetic traceability for biodiversity conservation, and provide a robust framework for the protection and valorization of local apple germplasms. Full article

Managing vegetative vigor is a critical challenge for apple production in subtropical regions, where high water availability often promotes excessive canopy growth. This study evaluated the effects of split applications of prohexadione–calcium (ProCa) combined with naphthaleneacetic acid (NAA) and ethephon on the vegetative growth and yield performance of ‘Maxi Gala’ and ‘Fuji Suprema’ apples during the 2022/23 and 2023/24 growing seasons. The experimental design consisted of six plant growth regulator (PGR) protocols: a commercial standard (Control) with two applications, and five protocols based on six split applications initiated when fruit diameter reached ~8 mm, with 10-day intervals. The treatments included ProCa; ProCa + NAA; ProCa + ethephon; ProCa + NAA + ethephon; and ethephon + NAA. The ProCa + NAA protocol demonstrated the highest efficiency in vigor control, reducing shoot growth by up to 38% in ‘Maxi Gala’ and 65% in ‘Fuji Suprema’ relative to Control. Furthermore, this treatment enhanced fruit skin coloration, increased the proportion of Category 1 fruit, and improved return bloom and overall yield. These findings suggest that split applications of ProCa associated with NAA provide a robust strategy to optimize apple orchard productivity under the edaphoclimatic conditions of southern Brazil. Full article

Efficient nitrogen (N) management in perennial fruit orchards is constrained by species-specific differences in N demand and fruit N removal, which can result in distinct soil N uptake patterns even under similar fertilization regimes. This study assessed whether apple (Malus domestica Borkh.) and sweet cherry (Prunus avium L.) orchards differ in soil mineral nitrogen (Nmin) composition by analyzing nitrate (NO₃⁻) and ammonium (NH₄⁺) stocks in topsoil (0–20 cm). Soil samples were collected in spring from a long-term orchard experiment over two consecutive years and from a commercial orchard on two sampling dates in Germany. In apple orchards, Nmin was dominated by NO₃⁻ (83%), whereas cherry orchards showed a more balanced composition (42% NO₃⁻ and 58% NH₄⁺). These patterns were consistent across years, sites, fertilization types (mineral or organic), and key soil properties, including total organic carbon and total nitrogen, but were not explained by these factors. The elevated NH₄⁺ proportion in cherry soils suggests a species-associated pattern in soil N dynamics. Overall, the results highlight species-associated differences in soil Nmin composition between apple and sweet cherry orchards. Accounting for tree species differences may therefore improve N management and enhance N use efficiency in apple and sweet cherry production. Full article

The yield of apple trees as a function of potassium fertilization and the critical levels (CLs) and sufficiency ranges (SRs) of K in the soil, leaves, and fruits were determined in two experiments (two orchards) in four crop seasons. Plants of “Royal Gala” and “Fuji Suprema” cultivars were treated with 0, 50, 100, 150, or 200 kg K₂O ha⁻¹ year⁻¹. Potassium was applied annually during the bud swelling phase and onto the soil surface in the projection of the plant canopy, without incorporation. Critical levels and SR were estimated by Bayesian segmented quantile regression models. The cultivar factor was the main source of variation in fruit yield, K concentration in leaves and pulp, and K exported by apples. The crop season was the second factor with the greatest contribution to apple yield and K concentrations in leaves. When data from all crop seasons and orchards were pooled, yield did not vary by K treatments. The concentration of K in the leaf and fruit pulp also did not change as a function of the K dose with grouped data. For fruit production, the CL of K in the soil was 170 mg dm⁻³ for both cultivars; 17.8 g kg⁻¹ and 15.8 g kg⁻¹ in leaf for “Fuji Suprema” and “Royal Gala”, respectively; 1150 mg kg⁻¹ and 1080 mg kg⁻¹ in fruit pulp for “Fuji Suprema” and “Royal Gala”, respectively. The lack of response to K fertilization indicates that the trees were operating within a nutritional plateau. Consequently, we recommend that K fertilization in subtropical apple orchards be guided strictly by soil and plant analysis. For orchards exceeding the soil critical level of 170 mg dm⁻³ and leaf concentrations of 17.8 g kg⁻¹ and 15.8 g kg⁻¹ in leaf for “Fuji Suprema” and “Royal Gala”, respectively, and 1150 mg kg⁻¹ and 1080 mg kg⁻¹ in fruit pulp for “Fuji Suprema” and “Royal Gala”, respectively, K applications may be reduced or temporarily withheld under similar high-K soil conditions, provided that soil and plant nutritional status are regularly monitored. This management strategy ensures high yields and more efficient and sustainable nutrient management. Full article

Apple (Malus domestica Borkh.) rootstocks play a key role in modern intensive orchard systems, where their accurate identification is essential for breeding, nursery production, and certification of planting material. This is particularly important in Kazakhstan, a recognized center of origin of cultivated apple, where local germplasm remains insufficiently characterized at the molecular level. In this study, we integrated simple sequence repeat (SSR) genotyping and morphological trait analysis to develop a reliable approach for the identification of clonal apple rootstocks cultivated in Kazakhstan. Five widely used rootstocks (Zhetysu 5, ARM-18, B-7-35, M9, and B9) were analyzed using 17 polymorphic SSR markers and 30 vegetative traits. SSR analysis revealed moderate genetic polymorphism (PIC = 0.28–0.54; He = 0.35–0.58) and enabled clear discrimination among all studied genotypes. Cluster analysis based on genetic distances grouped rootstocks according to their genetic similarity, reflecting their origin and differentiation. Morphological evaluation demonstrated significant phenotypic variability and identified correlations among key vegetative traits related to plant vigor and leaf development. The integration of molecular and morphological data allowed the development of comprehensive genotype profiles (“molecular–morphological passports”) for each rootstock, ensuring their reliable identification. The proposed approach provides a practical framework for the certification of planting material and the management of apple genetic resources in Kazakhstan. It can be applied to improve nursery systems, support breeding programs, and ensure the production of true-to-type planting material in modern horticulture. Full article

Apples (Malus domestica Borkh.) are among the most widely consumed fruits worldwide and represent a significant dietary source of phenolic compounds. Efficient extraction is a critical step for the isolation, characterization, and quantification of phenolic compounds. The extraction yield and composition are strongly influenced by multiple parameters, including solvent type and concentration, temperature, extraction time, solid-to-liquid ratio, and the presence and concentration of acidifying agents. This study aimed to optimize an ultrasound-assisted extraction (UAE) procedure using response surface methodology (RSM) to evaluate the effects of extraction temperature, solvent-to-sample ratio (SSR) and citric acid concentration on total phenolic content (TPC) and total flavonoid content (TFC). Statistical analysis showed that SSR and temperature were the most influential factors affecting phenolic recovery, while citric acid concentration exerted a secondary, interaction-driven effect. Optimization using a desirability function identified the operating conditions that maximized phenolic and flavonoid recovery: 55 °C, 10 mL/g SSR and 0.2% citric acid concentration. Model predictions were validated experimentally, confirming the reliability of the approach for TPC and TFC. Chlorogenic acid and flavan-3-ols, including monomers, such as catechin and epicatechin, and polymers such as procyanidins, were identified. Overall, the proposed approach provides a statistically supported framework for phenolic compound analysis in apples. Full article

The apple tree (Malus domestica Borkh.) is one of the most economically important fruit crops worldwide, and its productivity is increasingly affected by water deficit. Understanding genotype-specific physiological responses to water deficit is important for improving water deficit resilience in apple. This study evaluated the effects of water deficit (14 days) and subsequent rehydration (7 days) on eight apple genotypes (‘Galaval’, ‘Idared’, ‘Rubinstep’, ‘B11’, ‘HL 308’, ‘HL 2010’, ‘HL 2350’, and ‘HL 827’) grown under semi-controlled container conditions. Physiological parameters, including pigment content, gas exchange, chlorophyll fluorescence, water use efficiency, and leaf water status, were assessed. Water deficit affected all measured parameters, with responses differing among genotypes. In most cases, water deficit was associated with reduced gas exchange and chlorophyll fluorescence, as well as changes in pigment content and leaf water status. However, the magnitude and direction of these responses varied depending on genotype. Some genotypes (e.g., ‘HL 2350’ and ‘B11’) showed more stable physiological performance under water deficit conditions, while others (e.g., ‘Idared’ and ‘Rubinstep’) exhibited more pronounced changes. Rehydration resulted in partial recovery of physiological parameters, although values generally did not reach control levels within the experimental period. The results indicate substantial genotypic variability in physiological responses to short-term water deficit under controlled conditions. These findings provide useful information for further research on water deficit responses in apple; however, additional studies under field conditions and including growth and yield parameters are required to assess the agronomic relevance of the observed differences. Full article

Apple (Malus domestica Borkh.) is the most widely cultivated deciduous fruit tree with the largest industrial scale and the highest economic value in China. Fruit surface glossiness and plant stress tolerance are two core traits that determine the economic benefits and sustainable development of the apple industry. The plant epidermal cuticle is not only the core material basis for determining fruit glossiness but also the first barrier for plants to resist abiotic and biotic stresses. Glycosylphosphatidylinositol-anchored lipid transfer proteins (LTPGs) are the core functional factors mediating trans-cell wall lipid transport in plants. At present, the functions and action mechanisms of LTPG family members that simultaneously regulate fruit appearance quality and stress tolerance in apple remain largely unclear. In this study, we took the MdLTPG17 gene as the research object, clarified its biological function of stress resistance under drought stress, and dissected the molecular mechanism by which it mediates fruit glossiness formation via regulating fruit cuticle thickening. The results of this study provide important genetic resources and a theoretical basis for molecular breeding of stress resistance and targeted improvement of fruit appearance quality in apple. Full article

High-density apple (Malus domestica Borkh.) orchards yield fruits as early as three years after planting but nutrient inputs and availability are paramount to a successful orchard; sustainable practices that balance tree growth and production with environmental concerns are not widely available. In this three-year study, we implemented a split-plot design in three orchards across the Mid-Atlantic region of the USA to evaluate integrated soil management approaches that combine locally sourced carbon-based organic mulch with fertilizers on rhizosphere microbes and tree growth. Bacterial and fungal communities were sampled at the end of the first and third growing seasons in addition to soil and tree-related physicochemical properties. Mulch treatment showed the most significant effect on both the bacterial and fungal groups. Most of these changes reflect the increase in soil organic matter and the increase in carbon cycling. Sequence variants belonging to Flavobacteria and Cytophaga were enriched by the mulch application. A key result from this project is the suppression of the relative abundance of potential soil-borne plant fungal pathogens in all orchards in all years. Additionally, arbuscular mycorrhizal fungi were enriched under the mulch treatment. Microbial shifts accompanying the mulch treatments supported higher trunk cross-sectional areas by the third sampling year that increased by 33.5%. Fertilizer treatments had less pronounced effects on microbial communities. These results highlight the potential for using sustainable, integrated nutrient management strategies to promote healthy orchard soils and support vigorous tree growth while reducing fungal pathogens. Our work will contribute to regional and location-specific fertilizer recommendations for apple producers. Full article

The apple (Malus domestica Borkh.) is one of the most widely consumed fruits worldwide due to its pleasant sensory properties and rich phytochemical composition. Therefore, the present study aimed to comprehensively investigate the chemical composition, antioxidant activity, anticancer effects, and molecular interactions of peel and pulp extracts of the Hünkar apple cultivar collected from different locations, using a combined experimental and computational strategy. These factors had a big effect on the extracts’ phenolic composition and biological activity. Moreover, the anticancer results were corroborated by molecular docking analyses, which offered further understanding of the interactions between bioactive compounds and cancer-associated target proteins. This integrative approach underscores the impact of both biological and methodological variables on the antioxidant and anticancer properties of apple-derived extracts, reinforcing their potential as natural sources of bioactive compounds. Cytotoxic activity against HT-22 and C6 cell lines was evaluated using the MTT assay, showing dose- and time-dependent antiproliferative effects. Apple extracts exhibited anticancer effects that were dependent on dosage and duration. The activities of chemicals found in extracts of Hünkar apple samples collected from four different locations against brain cancer proteins (PDB ID: 2DME, 6YPE, 1RV1) were examined. ADME/T analysis was then performed on the three molecules with the highest activity. The quantum chemical properties of these three molecules were also examined using the Gaussian package program with B3LYP, HF, M062X level in 6–31g, 6–31++g, and 6–31++g(d,p) basis sets. Full article

In apple (Malus × domestica Borkh), temperature during flowering strongly influences ovule viability and reproductive success, particularly under changing climate conditions. Five apple cultivars—‘Red Aroma’, ‘Discovery’, ‘Elstar’, ‘Rubinstep’, and ‘Summerred’—were exposed to constant temperatures (8 °C, 12 °C, and 16 °C) in the days following anthesis to evaluate ovule degeneration. At six time points after anthesis, fluorescence-stained ovules were visually categorized to assess ovule vitality and degeneration stages. Ovule viability decreased in a highly temperature-dependent manner across all cultivars. High percentages of viable ovules were observed at 8 °C and 12 °C, whereas ovule senescence was significantly accelerated at 16 °C, leading to a rapid loss of viability. Based on fluorescence intensity, ovule degeneration is irreversible once initiated and involves both physiological and morphological changes at higher temperatures. The cultivar ‘Elstar’ exhibited the slowest loss of ovule viability, while the other cultivars showed more rapid degeneration. These findings demonstrate that both temperature and genetic background affect ovule viability, making this stage of the reproductive process crucial in the context of future climate change. Full article

This study examines the reproductive biology of five widely cultivated apple cultivars in Norway (‘Discovery’, ‘Rubinstep’, ‘Red Aroma’, ‘Elstar’, and ‘Asfari’), when crossed with the main pollenizers (‘Summerred’, ‘Discovery’, ‘Katja’, ‘Rubinstep’, ‘Red Aroma’, ‘Fryd’, and ‘Eden’, and two crab apples ‘Professor Sprenger’ and ‘Dolgo’), as well as under self-pollination and open pollination. The experiment was conducted over two seasons (2022–2023) in Hardanger, a region in Western Norway. Flowering time and overlap, in vitro pollen germination, pollen tube growth within the styles and ovary, embryo sac viability, fertilization success, and fruit set were analyzed as key reproductive parameters. Under broadly comparable climatic conditions across both seasons, the results showed that both mother cultivar and the pollenizer strongly influenced progamic processes and fruit set. Pollen tube growth through the pistil was generally faster and more successful in 2022 for all pollination combinations, resulting in a higher fruit set. The only exception was ‘Elstar’, which exhibited a higher fruit set in 2023. If a single optimal pollenizer were to be selected for each apple cultivar in Western Norway, it would be ‘Red Aroma’ for ‘Discovery’ and ‘Rubinstep’; ‘Rubinstep’ for ‘Red Aroma’ and ‘Elstar’; and ‘Professor Sprenger’ for ‘Asfari’. Based on pollen tube growth in vivo and the fruit set, cultivars ‘Discovery’, ‘Rubinstep’, ‘Red Aroma’, ‘Elstar’, and ‘Asfari’ showed self-incompatibility. Full article