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Copyright of MESO is the property of Zadruzna Stampa D.D. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Apple scab, caused by Venturia inaequalis, is one of the most damaging pathogens affecting apple species. Cross combinations were made between the Salva cv. (female parent), a valuable local cultivar known for its fruit quality and used as a donor of the Vf resistance gene, and Jonathan (male parent), a variety widely cultivated but susceptible to scab. The Vf gene was first identified in Malus floribunda Clone 821, which was subsequently transferred to commercial varieties through various breeding programs. To confirm the presence of the Vf gene, the progeny from this cross was tested using Marker-Assisted Selection (MAS) with one dominant primer pair (AM19) and two codominant primers (AL07 and VFC) to distinguish between homozygous and heterozygous genotypes. From the crossing, 67 hybrids were obtained, of which 35.8% (24 hybrids) were classified as resistant (heterozygous - Vfvf), while 64.2% (43 hybrids) were classified as susceptible (recessive homozygotes - vfvf). This population of hybrids resistance to Venturia inaequalis represents a good starting point in obtaining cultivars with resistance to scab. [ABSTRACT FROM AUTHOR]

Background: Understanding the molecular basis of sport mutations in fruit trees has the potential to accelerate generation of improved cultivars. Results: For this, we analyzed the genome of the apple tree that developed the RubyMac phenotype through a sport mutation that led to the characteristic fruit coloring of this variety. Overall, we found 46 somatic mutations that distinguished the mutant and wild-type branches of the tree. In addition, we found 54 somatic gene conversions (i.e., loss-of-heterozygosity mutations) that also distinguished the two parts of the tree. Approximately 20% of the mutations were specific to individual cell lineages, suggesting that they originated from the corresponding meristematic layers. Interestingly, the de novo mutations were enriched for GC = > AT transitions while the gene conversions showed the opposite bias for AT = > GC transitions, suggesting that GC-biased gene conversions have the potential to counteract the AT-bias of de novo mutations. By comparing the gene expression patterns in fruit skins from mutant and wild-type branches, we found 56 differentially expressed genes including 18 involved in anthocyanin biosynthesis. While none of the differently expressed genes harbored a somatic mutation, we found that some of them in regions of the genome that were recently associated with natural variation in fruit coloration. Conclusion: Our analysis revealed insights in the characteristics of somatic change, which not only included de novo mutations but also gene conversions. Some of these somatic changes displayed strong candidate mutations for the change in fruit coloration in RubyMac. [ABSTRACT FROM AUTHOR]

The prevalence of apples as the most widely consumed fruit globally does not exempt them from storage-related issues, resulting in substantial harvest losses. A prominent concern is the development of rot due to various factors during storage. This research endeavors to examine the influence of agrotechnological methods on the longevity of apples and the incidence of rot throughout storage. Apple trees (Malus domestica Borkh. cv. Rubin) grafted on dwarfing rootstocks P60 were planted in 2010 in single rows with a spacing of 1.25 m between trees and 3.5 m between rows. Eight combinations of different growth control measures (manual, mechanical pruning, spraying, trunk cutting) were selected for the experiment. The implementation of mechanical pruning, in conjunction with trunk cutting and Ca-prohexadione spraying, as well as summer pruning, detrimentally impacted the shelf life of apples. Examination of the storage period revealed a loss of 33–40% of the crop due to rot. Conversely, manual pruning sustained a consistent level of phenolic compounds throughout the storage period. Other pruning methods resulted in a notable increase in phenolic compounds, ranging from 67% to a two-fold rise compared to the compounds present at harvest. However, the integration of mechanical pruning with subsequent manual pruning not only significantly augmented the yield of apples but also yielded a shelf life akin to that of manually pruned apples. Following the analysis of the results, it is advisable to conduct mechanical pruning of the apples intended for storage along with supplementary manual pruning. [ABSTRACT FROM AUTHOR]

The cultivated apple (Malus domestica Borkh.) is an economically important fruit crop in countries worldwide, including Bosnia and Herzegovina (BIH).The gene bank activities in BIH were initiated in the 1930s and continued until the war in the 1990s, when much of the documentation was lost. Since then, uncoordinated efforts were made to establish apple collections in different regions, but a comprehensive analysis of genetic resources was lacking. This prompted the current study where we present the first thorough overview of the national genetic resources of BIH apples. Thus, we analyzed 165 accessions in the apple gene bank at the Institute for Genetic Resources (IGR) established at Banja Luka using the 20 K apple Infinium® single nucleotide polymorphism (SNP) array. We combined the results with previously published data on the germplasm collections at Srebrenik and Goražde, genotyped using the Axiom® Apple 480 K SNP array. In total, 234 accessions were included in the study of which 220 were presumed to be local cultivars and 14 were known international reference cultivars. We identified numerous genotypic duplicates within and between collections and suggested preferred names to be used in the future. We found the BIH germplasm to have relatively few parent-offspring relationships, particularly among local cultivars, which might reflect the country's history and patterns of apple cultivar introduction. A number of cultivars unique to BIH and a weakly defined genetic group were identified via STRUCTURE analysis, representing interesting targets for future research and preservation efforts. [ABSTRACT FROM AUTHOR]

Ascospores discharged at rainfall and dispersed by wind can provide long-distance spread of the European canker fungus, Neonectria ditissima. Ascospores are produced by perithecia which are the sexual reproductive stage. Diffuse knowledge exists on the seasonal pattern of perithecium formation under different climatic conditions. Therefore, the development of perithecia was observed for several successive seasons at five sites in three Northern European countries. In Norway and Finland, ripe perithecia were commonly recorded throughout the year, and on individual cankers continuously for up to 28 months. In contrast, asexual reproductive structures (sporodochia) were confined to the growing season in both countries. In Northern Germany an average of 51% of cankers developed ripe perithecia by late winter, and perithecial senescence ensued in late spring. On average, ripe perithecia were present on cankers for 22 weeks. In contrast, sporodochia were observed all year round. The timing of perithecium maturation correlated with the number of days with > 2 mm rainfall in July–September. The presence of mature perithecia and sporodochia for different lengths of time in different countries has implications for regional disease management strategies. [ABSTRACT FROM AUTHOR]

BACKGROUND: Environmentally‐friendly crop protection practices are needed to enhance the sustainability of current agricultural systems. This is crucial in orchards which are extensively treated to impair various pests, at the expense of natural enemies. However, the effect of a shift towards softer pest management on the beneficial arthropod community is poorly documented. Earwigs (Dermaptera: Forficulidae) and spiders (Araneae) are relevant groups to assess such effects because they are highly sensitive to agricultural practices. They were monitored for 6 and 4 years, respectively, in apple orchards under three pest management regimes: Organic, Low‐input and Conventional, with pest management being switched during the survey from a broad‐spectrum insecticide schedule to mating disruption in the latter one, and more selective compounds in all orchards. RESULTS: The survey displayed that earwig abundance (mainly Forficula auricularia) that was initially very low in the Conventional orchard (annual mean 0.5–1.7 earwigs per shelter in the 2010–2012 period) increased to the same level as that of Low‐input and Organic orchards (over 10 earwigs per shelter) in the same year that changes in pest management occurred. The epigeal and arboreal spider communities were not responsive, and no recovering was observed 4 years after change in practices. CONCLUSION: Predatory arthropod communities are differently affected over time by changes in pest management, most probably due to their biology (dispersion, reproduction rate, susceptibility to pesticides etc.). This outlines the importance of documenting the time required to recover after perturbations and build a natural enemy community to enhance pest control in a win‐win perspective. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The economic viability of orchard sanitation practices, is crucial for sustainable apple production. However, our knowledge in this area is limited, particularly after the fruit is stored in the high-energy-consuming ultra-low oxygen (ULO) storage system. The objective of this 3-year study was to investigate the cost-benefit ratios of five sanitation treatments (lime sulfur-Lime-S, leaf collection-Collect-L, mulching-Mulch-C, lime sulfur + leaf collection, leaf collection + mulching) in integrated and organic apple orchards, considering the sale of apples after 6-month ULO storage. Cost-benefit analyses determined cost, total revenue, revenue for class 1 fruit (fruits without scab infection) and income surplus. Costs of ULO storage were twice higher in the integrated orchard (mean 3,064 EUR ha−1) than in the organic one (mean 1,512 EUR ha−1). Direct costs of the two combined sanitation treatments were significantly higher than the Lime-S and Collect-L treatments across all years and orchard systems. Analysis of variance for total revenue, revenue for class 1 fruit and income surplus revealed significant differences among years, sanitation treatments, and orchard systems. The total revenue and revenue for class 1 fruit were significantly higher in the integrated orchard (10,787 and 10,557 EUR ha−1, respectively) than in the organic one (8,713 and 7,742 EUR ha−1, respectively). The lowest total revenue and revenue for class 1 fruit were obtained in the non-sanitized control, while highest were recorded in the Collect-L or Collect-L + Mulch-C treatments. Collect-L and Collect-L + Mulch-C treatments provided the highest income surplus in all years and orchard systems. Kernel density estimations and frequency distributions indicated the widest variability for total revenue and revenue for class 1 fruit in the integrated orchard system. Correlation and linear regression analyses revealed significant relationship between total revenue and revenue for class 1 fruit in both orchard systems. In conclusion, our study demonstrates that Collect-L and Collect-L + Mulch-C treatments offer the greatest economic benefit after 6-month ULO storage regardless of the orchard system employed.

Apple scab, caused by Venturia inaequalis, is one of the most damaging pathogens affecting apple species. Cross combinations were made between the Salva cv. (female parent), a valuable local cultivar known for its fruit quality and used as a donor of the Vf resistance gene, and Jonathan (male parent), a variety widely cultivated but susceptible to scab. The Vf gene was first identified in Malus floribunda Clone 821, which was subsequently transferred to commercial varieties through various breeding programs. To confirm the presence of the Vf gene, the progeny from this cross was tested using Marker-Assisted Selection (MAS) with one dominant primer pair (AM19) and two codominant primers (AL07 and VFC) to distinguish between homozygous and heterozygous genotypes. From the crossing, 67 hybrids were obtained, of which 35.8% (24 hybrids) were classified as resistant (heterozygous - Vfvf), while 64.2% (43 hybrids) were classified as susceptible (recessive homozygotes - vfvf). This population of hybrids resistance to Venturia inaequalis represents a good starting point in obtaining cultivars with resistance to scab.

Abstract Background Understanding the molecular basis of sport mutations in fruit trees has the potential to accelerate generation of improved cultivars. Results For this, we analyzed the genome of the apple tree that developed the RubyMac phenotype through a sport mutation that led to the characteristic fruit coloring of this variety. Overall, we found 46 somatic mutations that distinguished the mutant and wild-type branches of the tree. In addition, we found 54 somatic gene conversions (i.e., loss-of-heterozygosity mutations) that also distinguished the two parts of the tree. Approximately 20% of the mutations were specific to individual cell lineages, suggesting that they originated from the corresponding meristematic layers. Interestingly, the de novo mutations were enriched for GC = > AT transitions while the gene conversions showed the opposite bias for AT = > GC transitions, suggesting that GC-biased gene conversions have the potential to counteract the AT-bias of de novo mutations. By comparing the gene expression patterns in fruit skins from mutant and wild-type branches, we found 56 differentially expressed genes including 18 involved in anthocyanin biosynthesis. While none of the differently expressed genes harbored a somatic mutation, we found that some of them in regions of the genome that were recently associated with natural variation in fruit coloration. Conclusion Our analysis revealed insights in the characteristics of somatic change, which not only included de novo mutations but also gene conversions. Some of these somatic changes displayed strong candidate mutations for the change in fruit coloration in RubyMac.

Breeding programmes have selected cultivars with a lower chill requirement. Apple production in these regions is socioeconomically valuable since fruit is harvested earlier than cooler regions. Understanding the adaptability and phenotypic stability in subtropical climate regions across multiple cropping seasons is important to ensure high productivity. The aim here was to evaluate the adaptability and phenotypic stability of seven apple cultivars that have been selected for a subtropical climate region. Phenology and productivity was measured including the mean number of fruit per plant, fruit weight, production per plant, mean estimated yield, and sum of chill hours, from four production cycles. Fruit quality was assessed for fruit from two production cycles. The genotype × environment interaction was analysed by the GGE biplot method. The Z selection index, the seasonal variation contributed significantly to the performance of each cultivar. Eva had the highest accumulated yield during the four production cycles and Imperatriz and Gala, had the lowest yields. Chilling requirements were the lowest for the cultivars Princesa, Eva and Julieta. Eva, Princesa and Julieta were the most stable for yield and also for the Z index. Eva and Julieta were the most adaptable and stable in subtropical climate regions. [ABSTRACT FROM AUTHOR]

Cytospora species are important plant pathogens causing destructive canker and die-back diseases on numerous host plants worldwide. Accurate species identification in the genus Cytospora is difficult and requires a combination of morphological characteristics and sequence data from multi-genomic regions. This study examined the diversity of Cytospora species associated with canker, die-back, and decline disease of apple trees in West Azarbaijan province, Iran. A total of 38 strains were isolated and obtained in pure culture. Based on morphological observation and multi-gene phylogenetic analyses (ITS, LSU, ACT, and RPB2), they were identified as five species—Cytospora mali-domesticae sp. nov., C. michailidesiana sp. nov., C. miyandoabensis sp. nov., C. longiostiolata, and C. parasitica. Pathogenicity tests were conducted on 1–2-year-old shoots of "Golden Delicious" and "Red Delicious" apple cultivars in the laboratory. Discoloration of bark and wood of inoculated shoots and re-isolation/re-identification of inoculated isolates confirmed Koch's postulates. Apple is a new host (matrix nova) for C. longiostiolata, and this species represents a new record for the mycobiota of Asia. The results of this study provide valuable information on the diversity of Cytospora species associated with apple trees with canker, die-back, and decline disease in Iran and could assist in formulating ongoing disease management strategies. [ABSTRACT FROM AUTHOR]

The present study focused on three autochthonous varieties of apple trees belonging to the old Tuscany germplasm (central Italy), Chitignano, Mora and Ruggine, and aimed to (a) evaluate the presence of the four main latent viruses of apple trees (apple chlorotic leaf spot virus [ACLSV], apple mosaic virus [ApMV], apple stem grooving virus [ASGV] and apple stem pitting virus [ASPV]) and (b) elucidate the biochemical and physiological responses of apple leaves and fruits challenged by ACLSV (the only virus detected). Indeed, despite no visible symptoms being reported, more than half of the assayed trees tested positive for ACLSV, although it occurred only in Mora and Ruggine. ACLSV impaired the photosynthetic performance of apple trees, especially in Ruggine leaves, but variety‐specific responses in terms of reorganization of photosynthetic pigment and primary metabolites were reported. Mora showed a higher ability to trigger the de‐epoxidation state of xanthophylls and to accumulate α‐tocopherol, while d‐glucose and sucrose increased only in infected Ruggine leaves, probably as a signalling response and/or an osmotic adjustment of this variety under ACLSV infection. Unexpectedly, ACLSV infection slightly increased pome size, but it dramatically reduced their quality (i.e., soluble solids content), again especially in Ruggine, the only variety where reductions of d‐fructose, d‐glucose and malic acid contents were reported. Overall, the evidence here reported could offer valuable insights to effectively cope with the detrimental viral diseases affecting this species and to protect the production of one of the most consumed and appreciated fruits in the world. [ABSTRACT FROM AUTHOR]

Blue mold caused by Penicillium expansum infection results in severe postharvest deterioration of apples. Salicylic acid (SA) is an effective elicitor of fruit resistance. However, the metabolic mechanism of P. expansum infection of apples and the SA-mediated metabolic responses are still unknown. In this study, the metabolite changes during P. expansum infection of apples and SA-mediated disease resistance were explored by performing ultra-performance liquid chromatography and quadrupole-time-of-flight mass spectrometry. A total of 472 different metabolites were identified between the five groups of sample comparisons, and the correlated metabolic pathways were revealed by bioinformatics analysis. The upregulation of the tricarboxylic acid (TCA) cycle, galactose metabolism, and starch and sucrose metabolism reflected energy conversion for P. expansum invasion and fruit disease resistance. Changes in glyoxylate and dicarboxylate metabolism and carbapenem biosynthesis reflected the biosynthesis of virulence factors and secondary metabolites for fungal infection. Metabolic pathways related to apple natural disease resistance mainly included the upregulation of secondary metabolite biosynthesis and sphingolipid metabolism. SA promoted the TCA cycle, reactive oxygen metabolism, and secondary metabolite biosynthesis of apples for disease resistance. This study revealed the metabolic pathways of P. expansum infection of apples and SA-mediated disease resistance, which helps to improve the understanding of the pathogenic mechanism and disease control. [ABSTRACT FROM AUTHOR]

Apple (Malus domestica) is a reliable source of nutrients to increase the bioactive compounds intake in the human body. In the market, the development of apple is still growing, not only in the hybridization of new cultivars, but also in the functional food products, based on apple's bioactive compounds. In this paper, we review the recent studies about the chemical composition of apples, including carbohydrates, proteins, lipids, dietary fibers, minerals, vitamins, phenolics, and other compounds, from various cultivars, grown in different countries or regions. Among the bioactive compounds in apple, the phenolic compounds, including hydroxybenzoic acids, hydroxycinnamic acids, flavanols and their oligo- and polymeric structure, flavonols, dihydrochalcones, and anthocyanins, majorly contribute to beneficial biological impacts. Therefore, the extraction process might be the most critical step to recover all the phenolics from apple and could be used in various food product developments. In this paper, the comparison of conventional and developed phenolic extraction methods is also reviewed in various apple products (flesh, peel, pomace, pulp, etc.). The selection of food grade and green solvents in the optimal phenolic extraction methods could reduce the environmental issues, thus supports sustainability and can be safer for consumers. To sum up, this paper may help the readers, both at general household and industrial levels, to understand the nutritional composition of various apple cultivars from different regions and to select the optimum conditions for apple's phenolic extraction, based on recent studies. [ABSTRACT FROM AUTHOR]

The precise and automated diagnosis of apple leaf diseases is essential for maximizing apple yield and advancing agricultural development. Despite the widespread utilization of deep learning techniques, several challenges persist: (1) the presence of small disease spots on apple leaves poses difficulties for models to capture intricate features; (2) the high similarity among different types of apple leaf diseases complicates their differentiation; and (3) images with complex backgrounds often exhibit low contrast, thereby reducing classification accuracy. To tackle these challenges, we propose a three-residual fusion network known as MSCR-FuResNet (Fusion of Multi-scale Feature Extraction and Enhancements of Channels and Residual Blocks Net), which consists of three sub-networks: (1) enhancing detailed feature extraction through multi-scale feature extraction; (2) improving the discrimination of similar features by suppressing insignificant channels and pixels; and (3) increasing low-contrast feature extraction by modifying the activation function and residual blocks. The model was validated with a comprehensive dataset from public repositories, including Plant Village and Baidu Flying Paddle. Various data augmentation techniques were employed to address class imbalance. Experimental results demonstrate that the proposed model outperforms ResNet-50 with an accuracy of 97.27% on the constructed dataset, indicating significant advancements in apple leaf disease recognition. [ABSTRACT FROM AUTHOR]

Copyright of Glasnik Zastite Bilja is the property of Zadruzna Stampa D.D. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Microtubules undergo dynamic remodeling in response to diverse abiotic stress in plants. The plant-specific IQ67 DOMAIN (IQD) family proteins serve as microtubule-associated proteins, playing multifaceted roles in plant development and response to abiotic stress. However, the biological function of IQD genes in apple remains unclear. In this study, we conducted a comprehensive analysis of the Malus domestica genome, identifying 42 IQD genes distributed across 17 chromosomes and categorized them into four subgroups. Promoter analysis revealed the presence of stress-responsive elements. Subsequent expression analysis highlighted the significant upregulation of MdIQD17 and MdIQD28 in response to cold treatments, prompting their selection for further functional investigation. Subcellular localization studies confirmed the association of MdIQD17 and MdIQD28 with microtubules. Crucially, confocal microscopy and quantification revealed diminished microtubule depolymerization in cells transiently overexpressing MdIQD17 and MdIQD28 compared to wild-type cells during cold conditions. In conclusion, this study provides a comprehensive analysis of IQD genes in apple, elucidating their molecular mechanism in response to cold stress. [ABSTRACT FROM AUTHOR]

SUMMARY: In the field, necrosis area induced by pathogens is usually surrounded by a red circle in apple fruits. However, the underlying molecular mechanism of this phenomenon remains unclear. In this study, we demonstrated that accumulated salicylic acid (SA) induced by fungal infection promoted anthocyanin biosynthesis through MdNPR1‐MdTGA2.2 module in apple (Malus domestica). Inoculating apple fruits with Valsa mali or Botryosphaeria dothidea induced a red circle surrounding the necrosis area, which mimicked the phenotype observed in the field. The red circle accumulated a high level of anthocyanins, which was positively correlated with SA accumulation stimulated by fungal invasion. Further analysis showed that SA promoted anthocyanin biosynthesis in a dose‐dependent manner in both apple calli and fruits. We next demonstrated that MdNPR1, a master regulator of SA signaling, positively regulated anthocyanin biosynthesis in both apple and Arabidopsis. Moreover, MdNPR1 functioned as a co‐activator to interact with and enhance the transactivation activity of MdTGA2.2, which could directly bind to the promoters of anthocyanin biosynthetic and regulatory genes to promote their transcription. Suppressing expression of either MdNPR1 or MdTGA2.2 inhibited coloration of apple fruits, while overexpressing either of them significantly promoted fruit coloration. Finally, we revealed that silencing either MdNPR1 or MdTGA2.2 in apple fruits repressed SA‐induced fruit coloration. Therefore, our data determined that fungal‐induced SA promoted anthocyanin biosynthesis through MdNPR1‐MdTGA2.2 module, resulting in a red circle surrounding the necrosis area in apple fruits. Significance Statement: Pathogen‐stimulated salicylic acid promotes anthocyanin biosynthesis through MdNPR1‐MdTGA2.2 module, which facilitates formation of a red circle surrounding the necrosis region induced by pathogens. This work not only dissects a possible pathway that uncovers the molecular mechanism of pathogen‐induced anthocyanin accumulation but also complements and extends the biotic factors that modulate anthocyanin synthesis in plants. [ABSTRACT FROM AUTHOR]

Brazil is one of the world's largest apple (Malus domestica Borkh: Rosaceae) producers. Throughout the production cycle, the crop is susceptible to infestations of phytophagous mites. The aim of this work was to understand the response of the mite community to cultivars, plant stratum and the management of apple orchards. The study was performed in conventional orchards (Fuji and Gala) and organic (Gala, Fuji and Eva). Monthly collections were carried out over one year. Forty plants were sampled per orchard, being three leaves per plant (apical, median and basal). The material was sorted and identified in the laboratory. A total of 7.193 mites were collected, with organic orchards having a higher average abundance (10.1±3.37) than conventional ones (7.39±1.82). The relative abundance of Aculus schlechtendali Nalepa (Eriophyidae) and Panonychus ulmi (Koch) (Tetranychidae) was higher in the conventional system. Neoseiulus californicus (McGregor) (Phytoseiidae) had higher relative abundance in the conventional system, while the organic had a higher richness of predatory mites. The cultivars influenced the mite community, with Eva having the highest mean abundance (17.7±9.13), followed by Gala (8.96±2.52) and Fuji (5.12±1.25). Regarding the stratum, the apical region had the highest mite abundance (13.3±4.82), followed by the median (6.99±1.86) and basal (5.38±1.30). Organic orchards kept the mite community in balance, conserving richness and diversity, with low populations of phytophagous and a constant and diverse presence of natural enemies. [ABSTRACT FROM AUTHOR]

Lectins, a large group of proteins present in all kingdoms of life can bind reversibly to glycans. The roles of plant lectins are diverse and include resistance to biotic or abiotic stress, notably bacterial resistance. A gene family encoding amaranthin-like lectins termed MdAGGs in apple (Malus domestica) has been identified to be overexpressed upon treatment with the plant resistance inducer acibenzolar-S-methyl (ASM) which promotes enhanced resistance to the fire blight disease caused by Erwinia amylovora (Ea). In this study, we first screened the ability of purified MdAGG10 to agglutinate bacterial cells in vitro among a range of bacterial species. Several bacterial species, either Gram positive or negative, either plant- or human-pathogens were found to be agglutinated by MdAGG10 in acidic conditions. Apple and Arabidopsis lines constitutively overexpressing MdAGG10 were generated and evaluated for their resistance to, respectively, Ea and Ralstonia solanacearum, both plant pathogens that were found in our screening. Despite MdAGG10 protein accumulated in tissues of both apple and Arabidopsis lines, they remained susceptible to their respective pathogens. Interestingly, in vitro agglutination of Ea by MdAGG10 did not impair bacterial growth, suggesting that other plant molecules are involved in the resistance to fire blight triggered after an ASM treatment. [ABSTRACT FROM AUTHOR]

Apple cultivars 'Annurca' and 'Limoncella' are grown locally in the Campania region of Italy and are valued for their distinctive flavour and characteristics, including a high content of nutritionally important bioactive compounds. However, apples are typically stored chilled for several months before consumption, so it is important to assess if the valuable characteristics are still present after postharvest storage. Here, we compare the quality, nutritional parameters, and aroma of these two cultivars with two widely grown international cultivars, 'Golden Delicious' and 'Fuji', after 60 days of storage. The aroma profiles of all four apples were analysed using thermal desorption and gas chromatography–time-of-flight mass spectrometry. We show that the local cultivars are distinct from the international cultivars in their bioactive compound content and their antioxidant activity. 'Limoncella' shows high sugar content, which may be acting as a cryoprotectant during storage, and high total phenolics in the flesh, which is of nutritional interest. We identified 104 volatile organic compounds (VOCs) and showed that the overall aroma profile is distinct for each cultivar, containing 11 published odorant compounds. The 'Annurca' profile is uniquely low in esters. Seven VOCs retain good discrimination across the four cultivars and, together with the quality and nutritional data, separate the two local cultivars from the international cultivars by hierarchical clustering. Overall, the data emphasize the unique characteristics of the two local cultivars and their value. [ABSTRACT FROM AUTHOR]

Bitter pit is a disorder affecting the appearance of apples. Susceptibility is genetically controlled by both the cultivar and rootstock, with both environmental and horticultural factors affecting its severity and proportional incidence. Symptoms appear more frequently at the calyx end of the fruit and consist of circular necrotic spots, which take on a "corky" appearance visible through the peel. Bitter pit may develop before harvest, or after harvest, reducing the proportions of marketable fruit. In this review, current knowledge of the factors associated with the occurrence of bitter pit in apples is summarized and discussed along with their interactions with Ca uptake and distribution to fruit. This disorder has been previously linked with localized Ca deficiencies in fruit during its development. However, these relationships are not always clear. Even with over a century of research, the precise mechanisms involved in its development are still not fully understood. Additional factors also contribute to bitter pit development, like imbalances of mineral nutrients, low concentration of auxins, high concentration of gibberellins, changes in xylem functionality, or physiological responses to abiotic stress. Bitter pit remains a complex disorder with multiple factors contributing to its development including changes at whole plant and cellular scales. Apple growers must carefully navigate these complex interactions between genetics, environment, and management decisions to minimize bitter pit in susceptible cultivars. Accordingly, management of plant nutrition, fruit crop load, and tree vigor still stands as the most important contribution to reducing bitter pit development. Even so, there will be situations where the occurrence of bitter pit will be inevitable due to cultivar and/or abiotic stress conditions. [ABSTRACT FROM AUTHOR]

The study was carried out in 2021-2023 on a pome fruit species of apple (Malus domestica Borkh) grown in experimental orchards at Fruit Growing Institute Plovdiv. The present research aimed to study the spread of the viruses АрМV, ACLSV, АSGV, ASPV, and the phytoplasma Candidatus Phytoplasma mali’ (Ca P. mali’), the causal agents of economically important diseases on apple, that will allow us to determine the current viral status of certain apple cultivars. The following methods were used to achieve the goal: visual observations and marking of symptomatic and asymptomatic trees; the diagnostic method of immuno- enzyme binding ELISA for tests of the marked samples; and biological test by mechanical inoculation of herbaceous indicators. The results from virological analyses showed that in the tested apple trees ACLSV was the identified at the highest rate of 28.3% followed by ASPV, ASGV and ApMV detected in 25%, 11.6% and 5%, respectively. Mixed infections in various combinations were registered. Double mixed infections by ACLSV and ASPV as well by ACLSV and ASGV were found in 8.3% and 3.3% of the surveyed apple trees, respectively. Triple mixed infection by ACLSV, ASPV and ASGV was ascertained in 8.3% of tested samples. [ABSTRACT FROM AUTHOR]

This study aimed to assess oviposition of Panonychus ulmi (Koch, 1936) (Acari: Tetranychidae) in response of conspecific and heterospecific mites cues on apple trees (Malus domestica Borkh: Rosaceae). The oviposition of P. ulmi was measured on apple tree leaves with the presence of webs, eggs, and other cues of phytophagous mites (Aculus schlechtendali (Nalepa, 1890) (Acari: Eriophyidae), P. ulmi, Tetranychus urticae Koch, 1936 (Acari: Tetranychidae), and Tetranychus ludeni Zacher, 1913 (Acari: Tetranychidae)). The presence of conspecific webs and cues increased the oviposition of P. ulmi, while the presence of A. schlechtendali and T. urticae webs and eggs and A. schlechtendali cues decreased oviposition. The oviposition increases in the presence of conspecifics suggesting that P. ulmi performs better in environments without heterospecific mites. On the other hand, the P. ulmi decreases in oviposition in presence of heterospecific mite cues suggesting a potential competitive displacement of tetranychid by eriophyid mites.

Previous studies have highlighted the role of three quantitative trait loci (QTL, i.e. ‘qT1’, ‘qF11’ and ‘qF17’) in partial resistance to apple scab. Underlying molecular mechanisms of these loci are yet unknown. Exploring differential gene expression between apple genotypes carrying contrasting combinations of these QTLs could depict original candidate genes and pathways implicated. We therefore carried out RNA sequencing just before and five days after inoculation of the pathogenic fungi Venturia inaequalis, in sixteen genotypes from a pseudo-F1 progeny segregating for resistant or susceptible alleles of the three QTLs. The current dataset includes i) transcriptomic profile description, ii) analysis of differentially expressed genes related to none or combined QTLs, infected or not with Venturia inaequalis and iii) disease phenotyping of the same genetic materials. The raw data files have been deposited in the Gene Expression Omnibus (GEO) repository with the accession number GSE250309. These outputs represent the first step towards elucidating the genetic basis of quantitative apple scab resistance. In the long term, this data set will improve apple breeding strategies on how to combine qualitative (used so far) and quantitative resistances to apple scab, with the aim of diversifying selective pressures on the pathogen.

Abstract Background The genetic basis of colour development in red-flesh apples (Malus domestica Borkh) has been widely characterised; however, current models do not explain the observed variations in red pigmentation intensity and distribution. Available methods to evaluate the red-flesh trait rely on the estimation of an average overall colour using a discrete class notation index. However, colour variations among red-flesh cultivars are continuous while development of red colour is non-homogeneous and genotype-dependent. A robust estimation of red-flesh colour intensity and distribution is essential to fully capture the diversity among genotypes and provide a basis to enable identification of loci influencing the red-flesh trait. Results In this study, we developed a multivariable approach to evaluate the red-flesh trait in apple. This method was implemented to study the phenotypic diversity in a segregating hybrid F1 family (91 genotypes). We developed a Python pipeline based on image and colour analysis to quantitatively dissect the red-flesh pigmentation from RGB (Red Green Blue) images and compared the efficiency of RGB and CIEL*a*b* colour spaces in discriminating genotypes previously classified with a visual notation. Chemical destructive methods, including targeted-metabolite analysis using ultra-high performance liquid chromatography with ultraviolet detection (UPLC-UV), were performed to quantify major phenolic compounds in fruits’ flesh, as well as pH and water contents. Multivariate analyses were performed to study covariations of biochemical factors in relation to colour expression in CIEL*a*b* colour space. Our results indicate that anthocyanin, flavonol and flavanol concentrations, as well as pH, are closely related to flesh pigmentation in apple. Conclustion Extraction of colour descriptors combined to chemical analyses helped in discriminating genotypes in relation to their flesh colour. These results suggest that the red-flesh trait in apple is a complex trait associated with several biochemical factors.

Background. Physiological and biochemical research on winter stress resistance of apple-tree cultivars of different ecogeographic origin under global warming is important for identifying the most adaptable genotypes for use in breeding practice. Such resistance is associated with the content of carbohydrates and anthocyanins, and the activity of peroxidase.Materials and methods. Two winter apple-tree cultivars developed at the North Caucasian Federal Scientific Center of Horticulture, Viticulture, Wine making (NCFSCHVW) and 3 foreign winter cultivars were studied using conventional physiological and biochemical methods.Results and discussion. The apple-tree cultivars ‘Orfey’ and ‘Prikubanskoye’ bred at the NCFSCHVW, when compared with foreign cvs. ‘Enterprise’, ‘Florina’ and ‘Ligol’, demonstrated higher contents of total water (by 2.5 %), starch (by 9.5 mg/g) and water-soluble sugars (by 19.3 mg/g) in shoots during the winter period. In the process of wintering, the anthocyanin content increased 2.9–4.3 times in the domestic cultivars, and 2.4–2.8 times in foreign ones. No regularities were found between the level of total peroxidase activity and winter hardiness of the studied apple cultivars.Conclusion. Cvs. ‘Orfey’ and ‘Prikubanskoye’ showed increased adaptability to the winter conditions in the unstable climate of Southern Russia, and can be recommended for cultivation in Krasnodar Territory and use in breeding practice.

Domesticated apple is a drought-sensitive species that spread from continental to Mediterranean temperate regions, where it can particularly experience prolonged water stress. One strategy to improve drought resistance in apple is engrafting on selected rootstocks. This study explores the potential of fast chlorophyll a fluorescence for the comparison of rootstock sensitivity to drought, looking for significant correlations with fruit productivity. The experiment was conducted in a field located in the coastal Po River Plain, Northern Italy, characterized by a loamy sandy soil, particularly prone to drought (86% sand). Mature plants of apple cv. Superchief® Sandidge engrafted on three different rootstocks (CIVP21pbr, MM106, M26) were monitored throughout the summer of 2021 and compared between irrigated and non-irrigated parcels, and at the end of the season, fruit production was evaluated. Despite soil water tension only reaching −13 kPa, the non-irrigated plants experienced a small but consistent loss of Photosystem II (PSII) activity and a lesser capacity of light energy conservation in the photosynthetic electron transport chain. The fruit weight correlated with PSII photochemical indexes recorded during early drought, particularly FV/FM and PIABS; a correlation emerged between fruit number per plant and median values of electron transport parameters, including PITOT. Although all rootstocks underwent a 40% loss of productivity, the fluorescence parameters revealed a graded susceptibility to drought, M26 > CIVP21pbr > MM106, which matched well with the plant vigour. The least drought-sensitive MM106 produced less numerous but heavier fruits than the other two rootstocks. [ABSTRACT FROM AUTHOR]

Sucrose phosphate synthase (SPS) is an important link in the process of sugar metabolism. In addition, it is also involved in abiotic stresses in plants. In order to study the SPS gene family and its role in abiotic stress, we identified the MdSPS gene family members by bioinformatics methods such as correlation analysis, the HMM method, and the Clustering method, and analyzed the transient expression of MdSPS genes by quantitative real-time fluorescence analysis (qRT-PCR). The MdSPS gene family consists of a total of 19 members divided into three subfamilies distributed on 14 chromosomes in apples. The MdSPS gene family has 12 collinearity gene pairs, indicating significant duplication. Most members of this family contain a large number of plant hormone response elements, light-inducible elements, and abiotic stress response elements 2kb upstream of the promoter. Codon bias analysis shows that there are 28 high-frequency codons and no codons with strong preference in this family. Gene chip results showed that only MdSPS2, MdSPS3, MdSPS11, and MdSPS17 were up-regulated in roots, and they were all members of subfamily C. The qRT-PCR analysis showed that all members of this family responded significantly to drought stress, salt stress, and low temperature stress. Interestingly, the relative expression of MdSPS12 was significantly down-regulated under salt stress and low temperature stress. In addition, the expression of MdSPS3, MdSPS8, MdSPS11, and MdSPS17 was more than 20 fold higher than that of the control under drought stress, salt stress, and low temperature stress. These four genes could be candidates for molecular breeding in the MdSPS family. [ABSTRACT FROM AUTHOR]

The phyllosphere, a reservoir of diverse microbial life associated with plant health, harbors microbial communities that are subject to various complex ecological processes acting at multiple scales. In this study, we investigated the determinants of the spatiotemporal variation in bacterial and fungal communities within the apple tree phyllosphere, employing 16S and ITS amplicon sequencing. Our research assessed the impact of key factors—plant compartment, site, time, and cultivar—on the composition and diversity of leaf and flower microbial communities. Our analyses, based on samples collected from three cultivars in three orchards in 2022, revealed that site and time are the strongest drivers of apple tree phyllosphere microbial communities. Conversely, plant compartment and cultivar exhibited minor roles in explaining community composition and diversity. Predominantly, bacterial communities comprised Hymenobacter (25%) and Sphingomonas (10%), while the most relatively abundant fungal genera included Aureobasidium (27%) and Sporobolomyces (10%). Additionally, our results show a gradual decrease in alpha-diversity throughout the growth season. These findings emphasize the necessity to consider local microbial ecology dynamics in orchards, especially as many groups worldwide aim for the development of biocontrol strategies (e.g., by manipulating plant–microbe interactions). More research is needed to improve our understanding of the determinants of time and site-specific disparities within apple tree phyllosphere microbial communities across multiple years, locations, and cultivars. [ABSTRACT FROM AUTHOR]

Fungal endophytes inhabit a similar ecological niche to that occupied by many phytopathogens, with several pathogens isolated from healthy tissues in their latent phase. This study aimed to evaluate the pathogenicity, the colonisation ability, and the enzyme activity of 37 endophytic fungal isolates recovered from apparently healthy apple shoot and leaf tissues. The pathogenicity of the isolates was assessed on 'Royal Gala' and 'Braeburn' fruit and detached 'Royal Gala' shoots. For the non-pathogenic isolates, their ability to endophytically colonise detached 'Royal Gala' shoots was evaluated. Enzyme activity assays were undertaken to determine whether the pathogenicity of the endophytes was related to the production of the extracellular enzymes, amylase, cellulase, pectinase, protease, and xylanase. Of the 37 isolates studied, eight isolates, representing the genera Colletotrichum , Diaporthe , Fusarium, and Penicillium, were shown to be pathogenic on both apple shoots and fruit. Two isolates identified as Trichoderma atroviride , were pathogenic only on shoots, and three isolates, representing the genus Diaporthe , were pathogenic only on fruit. Of the remaining 24 isolates, 22 (Biscogniauxia (n = 8), Chaetomium (n = 4), Trichoderma (n = 3), Epicoccum (n = 2), Neosetophoma (n = 2), Xylaria (n = 1), Daldinia (n = 1), and Paraphaeosphaeria (n = 1)) were recovered from the inoculated apple shoots but two failed to colonise the shoot tissues. Of the isolates tested, 20 produced amylase, 15 cellulase, 25 pectinase, 26 protease, and 13 xylanase. There was no correlation between the range and type of enzymes produced by the isolates and their pathogenicity or ability to endophytically colonise the shoot tissue. The study showed that approximately one-third (13/37) of the isolates recovered from the apparently healthy apple shoot tissues were observed as latent pathogens. The isolates that did not cause disease symptoms may have the ability to reduce colonisation of apple tissues by pathogens including Neonectria ditissima associated with European canker of apple. • Latent plant pathogens isolated from healthy plant tissue identified as endophytes. • Pathogenicity and enzyme production of 37 fungal apple endophyte isolates assessed. • Thirteen isolates produced disease symptoms on apple fruit and/or detached shoots. • Twenty-two isolates endophytically colonised apple shoots, with no symptoms. • Enzyme production did not differentiate between pathogenic and endophytic isolates. [ABSTRACT FROM AUTHOR]

'Ruixue' apples were used as the test material to study the effect of 10 μM methyl jasmonate (MeJA) on the quality and cell wall metabolism of apples after 18 d of storage. The results showed that MeJA significantly decreased the respiratory rate, reduced the titratable acid content and maintained a high soluble solids content. MeJA has been shown to suppress the activities and gene expressions of WSP, CSP, ISP, and cellulose in contrast to the control group, thereby maintaining a lower cell permeability and higher exocarp firmness. MeJA significantly decreased the expression of MdACS, MdACO, MdPL, Mdgal, and MdPG genes in the apple exocarp when compared to the control group. In addition, the overexpression of MdPL18 increased the content of cell wall polysaccharides such as WSP and CSP, enhanced cell wall-degrading enzyme activities, and accelerated fruit ripening and softening, whereas silencing MdPL18 did the opposite. Together, these results demonstrate that exogenous MeJA maintains the Ruixue apple fruit quality by regulating the metabolism of cell wall substances. [ABSTRACT FROM AUTHOR]

Background The genetic basis of colour development in red-fesh apples (Malus domestica Borkh) has been widely characterised; however, current models do not explain the observed variations in red pigmentation intensity and dis‑ tribution. Available methods to evaluate the red-fesh trait rely on the estimation of an average overall colour using a discrete class notation index. However, colour variations among red-fesh cultivars are continuous while develop‑ ment of red colour is non-homogeneous and genotype-dependent. A robust estimation of red-fesh colour intensity and distribution is essential to fully capture the diversity among genotypes and provide a basis to enable identifca‑ tion of loci infuencing the red-fesh trait. Results In this study, we developed a multivariable approach to evaluate the red-fesh trait in apple. This method was implemented to study the phenotypic diversity in a segregating hybrid F1 family (91 genotypes). We developed a Python pipeline based on image and colour analysis to quantitatively dissect the red-fesh pigmentation from RGB (Red Green Blue) images and compared the efciency of RGB and CIEL*a*b* colour spaces in discriminating geno‑ types previously classifed with a visual notation. Chemical destructive methods, including targeted-metabolite analysis using ultra-high performance liquid chromatography with ultraviolet detection (UPLC-UV), were performed to quantify major phenolic compounds in fruits’ fesh, as well as pH and water contents. Multivariate analyses were performed to study covariations of biochemical factors in relation to colour expression in CIEL*a*b* colour space. Our results indicate that anthocyanin, favonol and favanol concentrations, as well as pH, are closely related to fesh pigmentation in apple. Conclustion Extraction of colour descriptors combined to chemical analyses helped in discriminating genotypes in relation to their fesh colour. These results suggest that the red-fesh trait in apple is a complex trait associated with several biochemical factors. [ABSTRACT FROM AUTHOR]

The effect of plant cultivar on the degree of mycorrhization and the benefits mediated by arbuscular mycorrhizal fungi (AMF) have been documented in many crops. In apple, a wide variety of rootstocks are commercially available; however, it is not clear whether some rootstock genotypes are more susceptible to mycorrhization than others and/or whether AMF species identity influences rootstock compatibility. This study addresses these questions by directly testing the ability/efficacy of four different AMF species (Rhizophagus irregularis, Septoglomus deserticola, Claroideoglomus claroideum or Claroideoglomus etunicatum) to colonize a variety of commercially available Geneva apple rootstock genotypes (G.11, G.41, G.210, G.969, and G.890). Briefly, micropropagated plantlets were inoculated with individual species of AMF or were not inoculated. The effects of the rootstock genotype/AMF interaction on mycorrhization, plant growth, and/or leaf nutrient concentrations were assessed. We found that both rootstock genotype and the identity of the AMF are significant sources of variation affecting the percentage of colonization. However, these factors largely operate independently in terms of the extent of root colonization. Among the AMF tested, C. etunicatum and R. irregularis represented the most compatible fungal partners, regardless of apple rootstock genotype. Among the rootstocks tested, semi-dwarfing rootstocks appeared to have an advantage over dwarfing rootstocks in regard to establishing and maintaining associations with AMF. Nutrient uptake and plant growth outcomes were also influenced in a rootstock genotype/AMF species-specific manner. Our findings suggest that matching host genetics with compatible AMF species has the potential to enhance agricultural practices in nursery and orchard systems. [ABSTRACT FROM AUTHOR]

Türkiye is a prominent contributor to pear and diverse pome fruit production. Pear fruit with unusual brown to black spots and rot symptoms observed in public marketplaces in Mardin province have raised concerns regarding postharvest fruit health. The consistent isolation of a fungus from these fruits revealed morphological features indicative of Neoscytalidium dimidiatum. Phylogenetic confirmation of its identity ensued through BLASTn searches targeting, the internal transcribed spacer (ITS) of ribosomal DNA, the partial translation elongation factor 1‐alpha gene (tef1), and the partial β‐tubulin gene (tub2). Pathogenicity evaluations were conducted on common pome fruits, namely pears, apples, and quinces, unveiling the susceptibility of all examined fruits to postharvest infection by this emergent pathogen. Furthermore, an investigation was carried out to discern the pathogen's response to varying temperature ranges on pear fruits, revealing that the most pronounced lesions occurred at 30°C, followed by 25°C, 35°C, and 20°C. Conversely, no lesion development was observed at 10°C, 15°C, or 40°C. To the best of our knowledge, this study represents the first report of N. dimidiatum as the etiological agent responsible for postharvest rot in pear fruit. The implications of these findings highlight the potential threat posed by this pathogen to pome fruits postharvest, especially in regions where cold storage facilities are not widely utilized, warranting increased vigilance and preventive measures. [ABSTRACT FROM AUTHOR]

Effective nutrient management necessitates monitoring of nutrient requirement, extent and timing of nutrient supply during the fruit development. To achieve a good nutrient balance and its impact on fruit quality, study of nutrient dynamics is of utmost importance as it provides an intriguing stratagem to control tree nutrient status. The research aimed at investigating seasonal patterns of nutrient concentrations in leaves and fruits of apple (Malus × domestica Borkh.) cv Silver Spur on various clonal rootstocks (MM106, M4 and M9) during the year 2019–2020 and their impact on fruit quality. For this purpose collection of leaf and fruit samples commenced from one month after full bloom (May 15) until harvesting (September 18) at an interval of twenty one days and samples were evaluated for both macro and micro-nutrients {Nitrogen (N), Phosphorus (P), Potassium (K), Calcium (Ca), Magnesium (Mg) and Boron (B)} and quality characteristics. In general, concentration of N, P, K and B declined continuously in both leaf and fruit toward the end of fruit maturation, whereas leaf Ca and Mg augmented along the cycle, however fruit Ca and Mg increased up to first fruit development stage and then decreased again signifying nutrient dilution along growing season and its effect on fruit quality. With respect to rootstocks, semi-vigorous rootstock MM106 recorded higher values for leaf and fruit nutrient concentrations as compared to dwarf M9 and semi-dwarf M4 rootstocks specifying a significant effect of rootstocks on nutrient absorption. [ABSTRACT FROM AUTHOR]

SUMMARY: Soluble sugar content is a key component in controlling fruit flavor, and its accumulation in fruit is largely determined by sugar metabolism and transportation. When the diurnal temperature range is greater, the fleshy fruits accumulated more soluble sugars and become more sweeter. However, the molecular mechanism underlying this response remains largely unknown. In this study, we verified that low‐temperature treatment promoted soluble sugar accumulation in apple fruit and found that this was due to the upregulation of the Tonoplast Sugar Transporter genes MdTST1/2. A combined strategy using assay for transposase‐accessible chromatin (ATAC) sequencing and gene expression and cis‐acting elements analyses, we identified two C‐repeat Binding Factors, MdCBF1 and MdCBF2, that were induced by low temperature and that might be upstream transcription factors of MdTST1/2. Further studies established that MdCBF1/2 could bind to the promoters of MdTST1/2 and activate their expression. Overexpression of MdCBF1 or MdCBF2 in apple calli and fruit significantly upregulated MdTST1/2 expression and increased the concentrations of glucose, fructose, and sucrose. Suppression of MdTST1 and/or MdTST2 in an MdCBF1/2‐overexpression background abolished the positive effect of MdCBF1/2 on sugar accumulation. In addition, simultaneous silencing of MdCBF1/2 downregulated MdTST1/2 expression and apple fruits failed to accumulate more sugars under low‐temperature conditions, indicating that MdCBF1/2‐mediated sugar accumulation was dependent on MdTST1/2 expression. Hence, we concluded that the MdCBF1/2‐MdTST1/2 module is crucial for sugar accumulation in apples in response to low temperatures. Our findings provide mechanistic components coordinating the relationship between low temperature and sugar accumulation as well as new avenues to improve fruit quality. Significance Statement: This study showed that low temperature induced the expression levels of the transcription factors genes MdCBF1/2 in apple, which could bind to the promoters of the tonoplast sugar transporter genes MdTST1/2 and activate their expression, leading to Glc, Fru, and Suc accumulation at high concentrations in the vacuoles. [ABSTRACT FROM AUTHOR]

This study investigated the properties of starch isolated from the unripe fruit of two apple cultivars (Malus domestica Borkh) grown in southern Poland (Central Europe). The chemical composition of both starches, molecular mass, their granulation, thermal characteristics, swelling characteristics, and rheological characteristics were studied. The starches differed significantly in ash, phosphorus, and protein content. The water-binding capacity at temperatures of 25–65 °C was similar, while differences of 20% appeared at higher temperatures. In contrast, a significant difference was found in the solubility of the two starches in the temperature range of 25–75 °C. The study showed that apple starches have a relatively low tendency to retrograde, with the enthalpy of gelatinization for starch from the Oliwka variety being 40% higher than that from the Pyros variety. However, the starches differed in the hardness of the gels formed, i.e., one variety formed soft gels with an internal structure resistant to external forces, while the other formed hard gels. [ABSTRACT FROM AUTHOR]

Apple Glomerella leaf spot (GLS) is an emerging fungal disease caused by Colletotrichum fructicola and other Colletotrichum species. These species are polyphyletic and it is currently unknown how these pathogens convergently evolved to infect apple. We generated chromosome‐level genome assemblies of a GLS‐adapted isolate and a non‐adapted isolate in C. fructicola using long‐read sequencing. Additionally, we resequenced 17 C. fructicola and C. aenigma isolates varying in GLS pathogenicity using short‐read sequencing. Genome comparisons revealed a conserved bipartite genome architecture involving minichromosomes (accessory chromosomes) shared by C. fructicola and other closely related species within the C. gloeosporioides species complex. Moreover, two repeat‐rich genomic regions (1.61 Mb in total) were specifically conserved among GLS‐pathogenic isolates in C. fructicola and C. aenigma. Single‐gene deletion of 10 accessory genes within the GLS‐specific regions of C. fructicola identified three that were essential for GLS pathogenicity. These genes encoded a putative non‐ribosomal peptide synthetase, a flavin‐binding monooxygenase and a small protein with unknown function. These results highlight the crucial role accessory genes play in the evolution of Colletotrichum pathogenicity and imply the significance of an unidentified secondary metabolite in GLS pathogenesis. [ABSTRACT FROM AUTHOR]

The main objective of the research was to assess weight loss, respiration rate, firmness, soluble solids content (SSC), titratable acidity and vitamin C content of the autochthonous Karasüt apple throughout cold storage. The 'Granny Smith' cultivar was used as positive control. The fruit was kept at a temperature of 0.0±0.5℃ and relative humidity of 90±5%. Quality losses were observed in the apples during cold storage. The weight loss of Karasüt apple (6.70%) was higher than that of Granny Smith (2.20%) at the end of cold storage. A lower respiration rate was measured in the Karasüt apple (1.23 nmol CO2 kg-1 s-1), compared to the positive control (1.53 nmol CO2 kg-1 s-1) at harvest. On the contrary, the respiration rate was higher on days 30 and 60. The fruit firmness of Granny Smith (27.14 N) was higher than that of Karasüt (22.47 N) at the end of cold storage. During the cold storage, a higher SSC was obtained from Karasüt apple compared to the positive control. However, titratable acidity was lower in Karasüt apple. In the first two measurements of cold storage, the vitamin C of Karasüt apple was higher than that of the positive control. As a result, it was revealed that Karasüt apple had faster quality losses during cold storage than Granny Smith apple cultivar. [ABSTRACT FROM AUTHOR]

Neonectria fruit rot (NFR), an apple disease caused by the fungus Neonectria ditissima, is common in Brazilian orchards, but several aspects of its epidemiology are not well elucidated. The objectives of this study were to: i) test in vitro germination of ascospores at different temperatures and wetness periods and compare with conidia germination, ii) evaluate and compare the monocyclic components of NFR caused by conidia and ascospore infection in wounded and unwounded ripe detached 'Gala' apple and iii) evaluate and compare the monocyclic components of NFR caused by conidia infection in 'Rocha' pear fruit under different temperatures. Germination of conidia and ascospores occurred in the range of 12–28 °C. At 35 °C no germination occurred, for both ascospores and conidia, regardless of the wetness period (3–60 h). With the same wetness period, conidia germination was always higher than ascospores at any temperature. For ascospores, the optimal temperature for germination ranged from 18–21 °C, lower than the estimated for conidia, which ranged from 21 to 24 °C. In wounded detached apple fruit, the incubation period varied from 35 to 49 days after ascospore inoculation, and for conidia from 14 to 42 days. When comparing the same temperatures, mean lesion growth rate was always higher for fruits inoculated with conidia than with ascospores. Unwounded fruits inoculated in the calyx-end did not present Neonectria fruit rot symptoms. The disease on 'Rocha' pear fruit has shorter incubation and latent periods than those of 'Gala' apple and higher AUDPC at 25 °C. The fast monocycle development represents a risk if the disease spread to pear orchards but also sets pear fruit as a good option for future NFR control studies. [ABSTRACT FROM AUTHOR]

The purpose of this study was to improve the protocol of clonal micropropagation for effective mass production of the Zarya Alatau apple cultivar through the use of axillary buds. In Kazakhstan’s challenging climate, the Zarya Alatau apple thrives because of its unique traits, including fruit preservation until May, cold hardiness, and resistance to scab and powdery mildew. Micropropagation is essential for healthy mother tree establishment, and this research focused on key factors for successful in vitro propagation. The sterilization of explants was optimized: 1.6% solution of sodium hypochlorite effectively sterilized plant materials for 10 minutes. Nutrient media composition was evaluated for efficient shoot regeneration. The study examined axillary bud regeneration on Murashige and Skoog medium with different concentrations of hormones. A combination of 6-benzylaminopurine (0.5 mg/L) and gibberellic acid (0.5 mg/L) yielded optimal results, with shoots reaching 3.5 cm. Root induction was analyzed with varying indole-3-acetic acid (IAA) concentrations, and the best results were achieved with 1.5 mg/L IAA, resulting in an 85% rooting frequency. Adapting in vitro plants to ex vitro conditions is crucial given their sensitivity to environmental changes. Well-developed leaves and a robust root system are essential for successful acclimatization during transplantation into a soil substrate. This research provides valuable insights into the critical parameters for a successful transition of in vitro propagated plants to soil conditions, optimizing micropropagation practices.

Russet formation in apple (Malus domestica Borkh.) is a superficial skin disorder that detracts from fruit appearance and is likely controlled by many small-effect quantitative trait loci (QTLs). Genomewide prediction has been reported to be an effective breeding approach when targeting highly quantitative traits in apple. Our objective was to investigate the utility of genomewide prediction for russet formation within an apple breeding program. Germplasm included 1,009 unselected offspring from 13 full-sib families derived from 14 breeding parents. 'Honeycrisp' and 'Minneiska', two breeding parents prone to moderate levels of russet, were highly represented. High-quality single nucleotide polymorphism data (947 SNPs) and three years of shoulder and lenticel russet formation data were leveraged in this study. Moderate predictive abilities (r = 0.28−0.35) were observed across training-testing set scenarios and models. In this germplasm, the inclusion of previously detected QTLs as fixed effects in the model did not have significant effects on predictive abilities. Postdiction (retrospective) analyses demonstrated that genomewide predictions and phenotypic observations agreed for 54% of advanced selections. Genomewide prediction is a promising approach when targeting russet formation, a trait that cannot be phenotypically observed in offspring in apple breeding programs until they are past their juvenile phase.

Retention of fruit firmness, as an important component of fruit quality during cold storage, is one of three primary targets of Washington State University's apple breeding program. Fruit firmness is phenotyped with a penetrometer to obtain firmness measurements of outer and inner fruit cortices. Since the breeding program's inception in 1994, substantial records of fruit firmness from Phase Two selections have been amassed, as part of its routine breeding evaluation. From 2005 to 2019, firmness data from at-harvest and after-storage samples were analyzed to describe 15-year trends in fruit firmness (and its postharvest retention) of the selections. Genetic backgrounds of selections were estimated using average allelic representation to describe pedigree relatedness of selections to cultivars and to quantify the potential influence of cultivar representation on the selections' firmness traits. Results showed that the breeding program has been selecting for increased fruit firmness and retention capacity postharvest (especially inner cortex) of the selections. The selections' increased inner cortex firmness coincided with increasing average allelic representation of 'Cripps Pink', suggesting the cultivar's influence in firmness at harvest and firmness retention during storage. 'Honeycrisp', another important breeding parent (as noted from the increasing average allelic representation from 0.10 to 0.40) has likely positively impacted firmness retention in the selections. In summary, the 15-year trend analysis highlighted the influence of important cultivars, such as Cripps Pink, Gala, and Honeycrisp, in fruit firmness and/or firmness retention of breeding program Phase Two selections.