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The process of identifying apple varieties holds pivotal importance in pomology and agricultural science. This intricate task not only aids growers in optimizing orchard management, but also profoundly impacts consumers and the apple industry as a whole. Selecting the right apple varieties tailored to specific environmental conditions and market demands is instrumental for the sustainability and economic viability of apple cultivation. Accurate apple variety identification further contributes to maintaining product quality and ensuring consumer satisfaction. Traditional identification methods, however, are susceptible to human error given the vast diversity of apple cultivars. In response, the integration of advanced technologies, including image processing and machine learning, has emerged as a promising approach to enhance accuracy and efficiency in apple variety identification, benefitting both the agricultural and commercial sectors. The classification of apple types involved feature extraction using three methods: MobileNetV2, EfficientNetV2B0, and a combination of GLCM and Color-Space algorithms from apple images. Machine learning models were then built to classify apple varieties, utilizing various algorithms such as support vector machine (SVM), k-nearest neighbors (Knn), random subspace (RSS), and random forest. In the case of "EfficientNetV2B0 + GLCM + Color-Space" and utilizing the ReliefF feature selection method, the random forest algorithm attains peak performance with an accuracy, precision, recall, and F-score all registering an impressive 98.33%. [ABSTRACT FROM AUTHOR]

Productivity is one of the primary economic and biological characteristics of an apple tree variety; it is this characteristic that determines the value and economic feasibility of the variety. The photosynthetic activity of the leaf surface of plants plays a leading role in forming the potential productivity of the apple tree. By "potential productivity," we mean the productivity of plants under conditions of ideal agroenvironment, optimal nutrition, and absence of diseases. To diagnose the potential productivity of cultivars we used an indicator of chlorophyll fluorescence induction–induction coefficient (Кі). According to our data, the Кі of leaves of columnar cultivars ranged from 0.720 to 0.740, indicating a high level of efficiency of photophysical processes near the photosystem II (PS II) reaction centers. For plants of columnar cultivars, the viability index ranged from 1.78 to 2.19. It has been established that individual age sections of tree trunks form different productivity potentials. Thus, based on the chlorophyll a (Chl a) fluorescence induction index, a higher intensity of photosynthesis was observed in the leaves of the cultivars ‘Valuta’, ‘Favoryt’, and ‘Bilosnizhka’ on seven to nine-year-old trunks. In contrast, for ‘Tantsivnytsia’, the highest intensity was observed on the oldest spur formation (14–19 years old). In traditional apple cultivars, the intensity of photosynthesis, as indicated by Кі, decreased with the age of spur formation; however, such a decline was not observed in columnar cultivars. The leaves of plants from the traditional cultivar ‘Idared’, situated on a homogeneous shoot, exhibited the highest photosynthetic intensity based on the F680γt / F680βt light intensity. Conversely, in the leaves of three-year-old spur formations, a 25.3% decrease in photosynthetic intensity was observed, falling to a 45.7% decrease in six-year-olds. With the optimal combination of agroecological factors for columnar cultivars, stability in the photosynthetic potential across various complex spur formations is observed. In typical apple cultivars, the age of spur formation leads to a suppression of photosynthetic intensity. The cultivar ‘Bilosnizhka’ is characterized by the highest Chl a/ Chl b content, indicating lower adaptability. In the leaves of this cultivar, the amount of Chl a exceeded Chl b by three times; in contrast, in the cultivars ‘Sparta’ and ‘Tantsivnytsia’, the difference was 2.5 times higher. This value (2.5x) correlates with increased adaptability to the conditions in which they were studied. The highest level of leaf net productivity of photosynthesis (NPP) is observed in plants of the ‘Valuta’ cultivar (13.9 g/m² for day); in the cultivars ‘Bilosnizhka’, ‘Favoryt’, ‘Bolero’, ‘Sparta’, ‘Tantsivnytsia’, and ‘Papirovka’, the accumulation of dry matter is lowered by 32.6–40.6%. [ABSTRACT FROM AUTHOR]

Fire blight of fruit crops is one of the most dangerous diseases for apple trees and other plants of the Rosaceae family, and in Kazakhstan, it is subject to quarantine. To study the spread of fire blight, a phytopathological evaluation of 59 apple varieties of domestic and foreign breeds was carried out in various regions of the south and southeast of Kazakhstan while also considering climatic conditions. The susceptibility of an apple tree to fire blight is influenced by the climatic conditions prevailing in a particular fruit region of Kazakhstan. Samples were collected from various varieties of apple trees with fire blight symptoms for molecular genetic analysis. The phytopathological evaluation and results of the PCR analysis made it possible to identify the causative agent of the disease and its spread to apple varieties in the main fruit regions of Kazakhstan. A molecular study of the resistance to the fire blight pathogen was carried out using the most effective molecular markers. A set of 10 (FBE-1_Y320; FBE-2_Y192; FBE-2_Y495; FBE-2_Y551; FB-MR5-K35; FB-MRS-R240; FB-MR5-R249; FB-MR5-rp16k15_M106; RLP1a; and RLP1b) SNPs was selected, including SNPs reported to be associated with three trait loci, as well as the two markers AE10-375 and GE-8019. Interestingly, the SNP analysis revealed that for all ten markers linked to fire blight resistance, the genotypes of all 59 apple cultivars were identical. No differences in the presence or absence of these markers were observed among the studied varieties. The 26 apple varieties of domestic and foreign breeds most resistant to fire blight were identified in the molecular analysis using the markers AE-375 and GE-8019. Among the studied 59 apple varieties, 23 varieties were identified using the AE-375 marker and 7 varieties with the GE-8019 marker. Samuret, Honeycrisp, Pinova, and Red Topaz were found to be resistant using markers AE-375 and GE-8019. The most promising apple varieties for further breeding for resistance to fire blight programs were selected. [ABSTRACT FROM AUTHOR]

Codling moth, Cydia pomonella L., is a major pest of pome fruits and walnuts worldwide. Screening the susceptibility of apple varieties to C. pomonella infestation is an important step to develop a sustainable management program against this pest. Therefore, the present study aimed to explore potential correlations between pest damage and several physical (firmness, weight, and diameter), chemical (pH, SSC, and TA), and biochemical (polyphenols) fruit properties collected from two sites with distinctively twelve and seven commercial apple varieties. The study was conducted in two distinct Moroccan regions to highlight whether the traits influencing the insect's preference could be similar for different varieties under contrasted climates. In both regions, results revealed that the pest damage varied significantly across apple varieties as well as between observation dates. The late and medium maturing varieties had similar damage patterns and were heavily attacked compared to early maturing ones. The preferred varieties were Galaxy Gala, Obro Gala, Golden Smoothee, Black Staymen, and Idared, while the least preferred ones were Anna, Dorsett, and Stark Delicious. Some physical and chemical fruit properties seemed to be associated with the insect behavior, in particular, firmness and pH were positively correlated to pest damage. Moreover, the research suggested that infestations might be influenced by diameter, weight, and polyphenol content of fruits. [ABSTRACT FROM AUTHOR]

In 1993, the apple buprestid, Agrilus mali Matsumura (Coleoptera: Buprestidae) native to northeast Asia, invaded the Yili River valley, Xinjiang Uyghur Autonomous Region, China. It is now widespread across 95% of wild apple forests (Malus sieversii (Ledeb.) Roem) in the region. This invasive species poses a major threat to wild apple populations serving as the key germplasm refuge for the ancestor of domestic apples across 6 countries in Central Eurasia. We first described the symptoms and damage caused by A. mali to wild apple trees, and then assessed the abundance of A. mali and tree damage under four different management strategies in three consecutive years (2016-2018): release of commercial biocontrol agents, aerial spraying of insecticide, aerial spraying/pruning, and establishment of fenced areas aiming to preserve understory vegetation and enhance natural pest control. The apple buprestid feeds on inner bark and preferentially damages the small branches (1-4 cm in diameter) located in the canopy 4-6 m above ground. The average fruit production declined from 90 kg to 10 kg per tree after the pest invasion. Pest abundance, as measured by counting damage scars, declined in sprayed areas. Fenced areas had higher pest abundance (damage). Fruit production in biological control and spraying/pruning areas increased slightly, while tree damage ranking declined over the years. Our results suggest that a combination of biological control and spraying/pruning may contribute to pest management of A. mali and resilience of wild apple forests in Central Eurasia. [ABSTRACT FROM AUTHOR]

Apple is among the most widely cultivated perennial fruit crops worldwide. It is sensitive to salt stress, which seriously affects the growth and productivity of apple trees by destroying the homeostasis of Na+ and K+. Previous studies focused on the molecular mechanism underlying NaCl stress. However, signaling transduction under KCl stress has not been thoroughly studied. We comprehensively analyzed the salt tolerance of Malus hupehensis Rehd., which is a widely used rootstock in apple orchards, by using RNA-Seq. Roots and leaves were treated with NaCl and KCl. Based on mapping analyses, a total of 762 differentially expressed genes (DEGs) related to NaCl and KCl stress in the roots and leaves were identified. Furthermore, we identified seven hub genes by WGCNA Analysis. The Gene Ontology (GO) terms were enriched in ion transmembrane transporter and oxidoreductase activity under NaCl and KCl stress. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways focused on the plant hormone signal transduction and mitogen-activated protein kinase signaling pathway. We also screened out 28 candidate genes from 762 DEGs and verified their expression by quantitative reverse transcription polymerase chain reaction (qRT-PCR). All of these enriched genes were closely related to NaCl and KCl stress and take part in mediating the Na+ and K+ homeostasis in M. hupehensis. This transcriptome analysis provides a valuable resource for elucidating the signaling pathway of NaCl and KCl stress and is a substantial genetic resource for discovering genes related to the NaCl and KCl stress response. • We firstly analyzed the molecular mechanism of M. hupehensis under KCl stress. • Our study explored 28 novel genes related to Na+ and K+ homeostasis in apple. • The MAPK signaling pathway is the main pathway related to salt stress in apple. [ABSTRACT FROM AUTHOR]

• A comprehensive orchard dataset is collected that covers different apple varieties and lighting conditions. • A deep learning-based apple detection framework is developed with a novel suppression network. • The developed Suppression Mask R-CNN framework outperforms existing state-of-the-art DNNs. Robotic apple harvesting has received much research attention in the past few years due to growing shortage and rising cost in labor. One key enabling technology towards automated harvesting is accurate and robust apple detection, which poses great challenges as a result of the complex orchard environment that involves varying lighting conditions and foliage/branch occlusions. This letter reports on the development of a novel deep learning-based apple detection framework named Suppression Mask R-CNN. Specifically, we first collect a comprehensive apple orchard dataset for "Gala" and "Blondee" apples, using a color camera, under different lighting conditions (overcast and front lighting vs. back lighting). We then develop a novel suppression Mask R-CNN for apple detection, in which a suppression branch is added to the standard Mask R-CNN to suppress non-apple features generated by the original network. Comprehensive evaluations are performed, which show that the developed suppression Mask R-CNN network outperforms state-of-the-art models with a higher F1-score of 0.905 and a detection time of 0.25 second per frame on a standard desktop computer. [ABSTRACT FROM AUTHOR]

Frequent extreme climate events have attracted considerable attention around the world. Malus sieversii in Xinjiang is the ancestor of cultivated apple, and it is mainly distributed in the Ili river valley at end of the Tianshan Mountains. Wild fruit forests have been degraded, but the cause remains unclear. In order to identify whether extreme climate events caused this degradation reanalysis data and atmospheric circulation indices were used to determine the trends and the reasons for extreme climate changes. Subsequently, we further investigated the effect of extreme climate events on wild fruit forest using characteristics of extreme climate indices and tree-ring chronology. We found increasing trends in both extreme precipitation and warm indices, and decreasing trends in cool indices. Extreme climate events were mainly associated with the Atlantic Multidecadal Oscillation (AMO). Analysis of data of wind and geopotential height field at 500 hPa showed that strengthening wind, increasing geopotential height, cyclone and anti-cyclone circulation drivers contributed to extreme climate events. In the non-degraded region, there were significant positive correlations between tree-ring chronology and both extreme precipitation and extreme warm indices (except for warm spell duration indicator). The other extreme indices (except for heavy rain days) had a large correlation range with tree-rings in a 4–8-year period. These results indicated that extreme precipitation and extreme warm indices intensified M. sieversii growth of the non-degraded region on multi-time scales. In contrast, the degraded region showed insignificant negative relationship between tree-ring chronology and both extreme precipitation and extreme warm indices [except for warm spell duration index (WSDI)], and significant negative correlations in a 4–8-year period were detected between tree-ring chronology and most of the extreme precipitation indices, including heavy rain days, very wet days, cold spell duration indicator, simple precipitation intensity index (SDII), and annual total precipitation. Under the long disturbance of inappropriate anthropic activities, extreme climate has caused the outbreak of pests and diseases resulting in the degeneration of wild fruit forest. Our study provides scientific guidance for the ecosystem conservation in wild fruit forest in China, and also across the region. [ABSTRACT FROM AUTHOR]

Background: Apple tree fruits (Malus × domestica Borkh.) are a rich source of nutrients and nutraceuticals and are recommended as a part of the healthy, staple diet. However, apples could be also the cause of allergies including severe reactions. Allergies to fruits like apples are predominantly associated with pollinosis. In North and Central Europe, sensitisation to apples is caused mainly by cross‐reactive birch pollen aeroallergen, whereas in the Mediterranean area of Europe, apple allergy is mostly associated with allergies to peach. The allergenicity of apples differ across cultivars but only a few varieties were studied. Some factors changing apples allergenicity were identified, including unmodifiable and potentially modifiable factors for example cultivation method, ripening stage and storage conditions. Aim: This review presents current knowledge about the molecular basis of apple allergenicity and factors influencing its level. Conclusions: Selecting cultivars with low potential of allergenicity, removing apple peel and heat treatment could reduce the risk of severe allergy reaction incidence and presumably can be used in birch pollen immunotherapy. [ABSTRACT FROM AUTHOR]

Aims: Salinity plays a crucial role in numerous environmental processes, with extreme concentrations resulting in the serious decline of global agricultural productivity. Plant-specific HD-Zip I transcription factors (TFs), particularly γ-clade HD-Zip I members, are key for the adaption of plants to various abiotic stresses. Our main purpose is to characterize the function of γ-clade HD-Zip I members in apple under salt stress. Methods: GL-3 and transgenic plants were grown in a hydroponic system or in soil and exposed to the presence or absence of NaCl. Photosynthetic capacity, root damage, Na+ and K+ accumulation, reactive oxygen species (ROS) accumulation, and RNA-seq were investigated. Results: MdHB-7 (γ-clade HD-Zip I TF) expression was induced by salt stress, particularly in the roots. We employed MdHB-7 overexpression and MdHB-7 RNAi transgenic apple plants for the treatments to explore the functions of MdHB-7 under salt stress. Results from the salt treatment and phenotypic evaluation revealed the enhancement of the salt tolerance of apple plants by the MdHB-7 expression. The overexpression of MdHB-7 reduced the salt stress-induced damage to root growth and vitality and maintained ion homeostasis. Moreover, the overexpression of MdHB-7 was observed to promote the detoxification of ROS. Transcriptome and qRT-PCR analysis demonstrate that MdHB-7 overexpression up-regulated the expression of antioxidant enzyme-related genes. MdHB-7-mediated root vitality, antioxidant activity and ion homeostasis were impaired, resulting in MdHB-7 RNAi lines that were more sensitive to salt stress. Conclusions: Our results demonstrate the key role of MdHB-7 as a salinity stress tolerance regulator in apple (Malus domestica). [ABSTRACT FROM AUTHOR]

In apple (Malus spp.), crown gall disease, caused by the bacterial pathogens Rhizobium radiobacter (Ti) and R. rhizogenes (Ti), can be severe. To control the disease, breeding of apple rootstocks that exhibit crown gall resistance is a promising approach. In this study, we used a full-sib F1 population derived from a 'JM7' (susceptible) × Sanashi 63 (resistant) cross to identify quantitative trait loci (QTLs) that control resistance to tumour-inducing Rhizobium isolates found in apple production areas in Japan. Three stable QTLs, associated with a wide range of crown gall resistances, were identified in three linkage groups (LGs). QTLs for resistance to isolates Peach CG8331, Nagano 1 and Nagano 2 co-localised at the middle of LG 2 in Sanashi 63, where the crown gall resistance gene Cg (renamed as Rrr1 in this study) was previously identified. Similarly, in 'JM7', QTLs were identified on LG 11 for resistance to isolates ARAT-001, ARAT-002 and Kazuno 2, and on LG 15 for resistance to isolate ARAT-001. Fine-mapping of Rrr1 and nucleotide sequencing of a contig obtained from two bacterial artificial chromosome (BAC) clones delimited the Rrr1 gene to a region spanning 217 kb. In silico gene prediction from the region identified four genes encoding the Toll-interleukin-1 receptor/nucleotide-binding site/leucine-rich repeat (TIR-NBS-LRR) class plant resistance genes. [ABSTRACT FROM AUTHOR]

Recombination leads to the generation of new viral progeny which remain undetected by routine testing procedures and may be a threat to the infected host. Here, we have characterised the complete genome sequences of two isolates of Apple stem pitting virus from apple cv. Red Chief (Palampur) and cv. Gold Spur (N) with distinct serological reactivities. The viral genomes consisted of 9267 nucleotides for isolate Palampur and 9254 nucleotides for isolate N, excluding the poly (A) tail and contained 5five open reading frames (ORFs). Isolate N shared 80.8% sequence identity with ASPV apple isolate GA2 from China, while isolate Palampur shared 81.4% sequence identity with ASPV apple isolate PB66 from the United Kingdom. The serological difference of isolates N and Palampur along with their low sequence identity indicated the existence of two distinct virus genotypes which was corroborated by evolutionary and genetic differentiation analyses. Recombination events were detected in the RdRp and CP sequences of Palampur isolate thereby suggesting the role of recombination in the evolution of distinct virus genotypes. [ABSTRACT FROM AUTHOR]

Applying large amounts of potash fertilizer in apple orchards for high apple quality and yield aggravates KCl stress. As a phytoalexin, resveratrol (Res) participates in plant resistance to biotic stress. However, its role in relation to KCl stress has never been reported. Herein we investigated the role of Res in KCl stress response of Malus hupehensis Rehd., a widely used apple rootstock in China which is sensitive to KCl stress. KCl-stressed apple seedlings showed significant wilting phenotype and decline in photosynthetic rate, and the application of 100 μmol Res alleviated KCl stress and maintained photosynthetic capacity. Exogenous Res can strengthen the activities of peroxidase and catalase, thus eliminating reactive oxygen species production induced by KCl stress. Moreover, exogenous Res can decrease the electrolyte leakage by accumulating proline for osmotic balance under KCl stress. Furthermore, exogenous Res application can affect K+/Na+ homeostasis in cytoplasm by enhancing K+ efflux outside the cells, inhibiting Na+ efflux and K+ absorption, and compartmentalizing K+ into vacuoles through regulating the expression of K+ and Na+ transporter genes. These findings provide a theoretical basis for the application of exogenous Res to relieve the KCl stress of apples. [ABSTRACT FROM AUTHOR]

Summary: High‐temperature fermented apple is a new fermented product with characteristic black appearance, which is prepared through natural fermentation of whole fresh apple at controlled high temperature (60–90 °C) and humidity (relative humidity of 50–90%). In this work, melanoidins from high‐temperature fermented apple were obtained by ultrafiltration and subsequent diafiltration. The structural characterisation of melanoidins was investigated in the present study. Results showed that the molecular weight of the obtained melanoidins was about 179 kDa and the melanoidins were comprised primarily of furans by pyrolysis–gas chromatography–mass spectrometry. Antioxidant activities of the high‐temperature fermented apple and its melanoidins were evaluated by ABTS, DPPH, hydroxyl radicals, ferric reducing antioxidant power and Fe2+‐chelating assays. Both high‐temperature fermented apple and its melanoidins showed extremely high antioxidant activities in scavenging hydroxyl radicals. High correlation between the antioxidant activity assayed methods and the physicochemical characteristics of melanoidins was obtained. The contribution of melanoidins to the total antioxidant capacity of high‐temperature fermented apple was determined. [ABSTRACT FROM AUTHOR]

Apple (Malus domestica Borkh.) is one of the most widely produced and economically important fruits in temperate regions. Fruit color development in apple is a major focus for both breeders and researchers as consumers associate brightly colored red apples with ripeness and a good flavor. In recent years, great progress has been made in the research of apple fruit color development, but its development mechanism has not been systematic dissected from the aspects of genetics, transcription or environmental factors. Here, we summarize research on the coloration of apple fruit, including the development of important genomic databases to identify important genomic regions and genes, genetic and transcriptional factors that regulate pigment accumulation, environmental factors that affect anthocyanin synthesis, and the current breeding progress of red-skinned and red-fleshed apples. We describe key transcription factors, such as MYB, bHLH, and WD40, which are involved in the regulation of anthocyanin synthesis and fruit color development in apple. We also discuss the regulation of apple color by external environmental factors such as light, temperature, and water. The aim of this review is to provide insights into the molecular mechanisms underlying anthocyanin biosynthesis in apple. This information will provide significant guidance for the breeding of high-quality red-skinned and red-fleshed apple varieties. • This review discussed the development mechanism of apple fruit color from the perspective of multi-disciplinary and multi-factor integration. • This review analyzed genomic databases of apples over the years to identify genomic regions and genes related to fruit color development. • This review described key transcription factors, such as MYB, bHLH, and WD40, which are involved in the fruit color development in apple. • This review discussed the regulation of apple color by external environmental factors such as light, temperature, and water. • We not only systematically summarized previous studies, but also looks forward to the future cultivation of red-skinned and red-fleshed apples. [ABSTRACT FROM AUTHOR]

Malus × arnoldiana accession MAL0004 has been found to be resistant to moderately and highly virulent strains of the fire blight causal pathogen – the Gram-negative bacterium, Erwinia amylovora. Genetic analyses with an F1 segregating population derived from crossing the highly susceptible apple cultivar 'Idared' and MAL0004 led to the detection and mapping of the fire blight resistance locus of M. ×arnoldiana to linkage group (LG)12 (FB_Mar12). FB_Mar12 mapped at the distal end of LG12 below the apple SSR Hi07f01 in an interval of approximately 6 cM (Centimorgan), where both the fire blight resistance loci of M. floribunda 821 and 'Evereste' were located. We fine mapped the region containing FB_Mar12 using 892 progenies. Mining of the region of interest (ROI) on the 'Golden Delicious' doubled haploid genome (GDDH13) identified the presence of 2.3 Mb (megabases) in the homologous region. Of 40 primer pairs designed within this region, 20 were polymorphic and nine were mapped, leading to the identification of 24 significant recombinant individuals whose phenotypes were informative in determining the precise position of the locus within a 0.57 cM interval. Analyses of tightly linked marker sequences on the M. baccata draft genome revealed scaffolds of interest putatively harboring the resistance loci of M. ×arnoldiana , a hybrid between M. baccata and M. floribunda. Open reading frame (ORF) analyses led to the prediction of first fire blight resistance candidate genes with serine/threonine kinase and leucine-rich repeat domains, including homologs of previously identified 'Evereste' candidate genes. We discuss the implications of these results on breeding for resistance to fire blight. [ABSTRACT FROM AUTHOR]

Malus xiaojinensis Cheng et Jiang is a special and significant germplasm resource of semi-dwarf apple in China. Abiotic stresses, such as Fe and high salinity, affect Malus xiaojinensis growth and development. WRKY transcription factors (TFs) are widely involved in the responses of plants to different stresses. In the present study, a new WRKY gene was isolated from Malus xiaojinensis and designated as MxWRKY64. Subcellular localization showed that MxWRKY64 was a nucleus localized protein. The expression level of MxWRKY64 was highly affected by Fe and salt stress in M. xiaojinensis seedlings. When MxWRKY64 was introduced into Arabidopsis thaliana, it greatly increased the Fe and salt tolerance in transgenic plant. When dealt with Fe stress, overexpression of MxWRKY64 in transgenic A. thaliana contributed to higher levels of fresh weight, root length, and contents of chlorophyll and Fe than wild type (WT). Increased expression of MxWRKY64 in transgenic A. thaliana also resulted in higher activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), higher contents of proline and chlorophyll, while malondialdehyde (MDA) content was lower, especially in response to salt stress. Therefore, these results suggest that MxWRKY64 probably plays an important role in response to Fe and salt stress in Arabidopsis. [ABSTRACT FROM AUTHOR]

Aims: In China, apple production areas are largely from the coastal to inland areas and across varied climate zones. However, the relationship among soil micro‐organisms, environmental factors and fruit quality has not been clearly confirmed in orchards. Here we attempted to identify the variation of soil bacteria in the main apple producing regions and reveal the relationship among climatic factor, soil properties, soil bacterial community and fruit quality. Methods and Results: Sixty soil samples were collected from six main apple producing areas in China. We examined the soil bacteria using bacterial 16S rRNA gene amplicon profiling. The results show that the soil bacterial diversity of apple orchards varied from the Bohai Bay Region to the Loess Plateau Region. Proteobacteria, Acidobacteria and Actinobacteria were the predominant taxa at the phylum level for all six areas. In the Bohai Bay and the Loess Plateau region, which are the two largest apple producing areas, Proteobacteria and Actinobacteria had the highest relative abundance, respectively. Furthermore, soil bacterial diversity showed positive correlation with the mean annual temperature (MAT), soil organic matter (SOM) and pH. Excluding a direct effect on the apple fruit quality, MAT exerted an indirect influence through soil SOM and pH to alter the relative abundance of dominant taxa and shift the bacterial diversity, which affects the apple fruit titratable acids and soluble solids. Conclusions: Geographic variables underlie apple orchard soil bacterial communities vary according to spatial scale. Environmental factors exert an indirect effect on apple fruit quality via shaping soil bacterial community. Significance and Impact of the Study: This study provides a list of bacteria associated with environmental factors and the ecological attributes of their interactions in apple orchards, which will improve our ability to promote soil bacterial functional capabilities in order to reduce the fertilizer input and enhance the fruit quality. [ABSTRACT FROM AUTHOR]

Finding an environmentally friendly way to utilize thinned young apple (TYA) fruits is of great interest in food industry since they were found rich in functional phytochemicals. Making TYA juice is an excellent way but very limited knowledge has been acquired. The juice‐making procedures optimization of a red‐fleshed and six varieties of TYA fruits were performed with/without steam sterilization before juicing, and the color index, phytochemicals particularly including phenolics and aromas were detailed characterized. Results showed that steaming sterilization of seven TYA were observed conducive to color stability and maintenance, higher sugar contents, comparable acid contents, but lower juice yield and total polyphenol in TYA juices. Moreover, similar polyphenol profiles were detected. Typical 22 aroma compounds were characterized with different profiles and trends in TYA juices. All these findings provide scientific basis for TYA juice making, and demonstrated that TYAs are of great value to develop seasoning juice products. Practical application: Fruit thinning is a necessary measure to improve fruit quality in apple production. Thinned young apples can expand the fruit gap through thinning, which is convenient for fruit expansion.The abandoned TYAs in the orchard are posing a risk of environmental pollution, or become host of pathogens to accelerate the spread of fruit diseases. Moreover, discarding the TYAs is a waste of agricultural and food resource since the content of total extractable polyphenols in TYAs is as high as 10 times that in ripe apples. More optimization of processing techniques such as making juice were suggested to improve TYA utilization including the extraction of polyphenols, polysaccharides, and aromas. More food or cosmetics products are expected to be developed based on the TYA juices to improve the commercial value and find an environmentally friendly way to make use of the thinned young fruit. [ABSTRACT FROM AUTHOR]

The Japanese beetle, Popillia japonica Newman, is an invasive insect to the United States that feeds on turfgrass roots as a larva and the foliage, flowers, and fruit of many major ornamental and agricultural crops, such as apple, as an adult. Despite its generalist feeding behavior, P. japonica shows preferences for certain plant species and cultivars. Classical biological control for P. japonica , including release of Istocheta aldrichi (Mensil), has been pursued in Minnesota. This study was conducted to assess the effects of apple cultivar on season-long abundance of adult P. japonica and their defoliation; and to assess effects of apple cultivar and P. japonica abundance and sex on parasitism of P. japonica by I. aldrichi. Sampling occurred during the summers of 2017 and 2018 on Zestar! and Honeycrisp cultivars in four different apple orchards. Abundance and defoliation of P. japonica was higher on Honeycrisp than Zestar!. Parasitism of P. japonica by I. aldrichi was higher for females than for males. In 2018, the relationship between parasitism of P. japonica and host density varied by cultivar. These findings may help growers determine which apple cultivars should be prioritized for scouting and management efforts and may provide an estimate of potential biological control by I. aldrichi in agricultural areas in the Midwest. [ABSTRACT FROM AUTHOR]

Brassinosteroid signaling downstream genes regulate many important agronomic traits in rice. However, information on such genes is limited in Arabidopsis and Rosaceae species. We identified these genes in Arabidopsis and nine Rosaceae species. They were, respectively, named based on chromosomal locations. Segmental duplication and whole-genome duplication under purifying selection, as determined by Ka/Ks analysis, likely contributed to Rosaceae gene expansion. Apple (Malus domestica), Arabidopsis , and rice genes were generally similar, while several Rosaceae genes differed from their rice homologs in various characteristics, such as gene length, subcellular localization, transmembrane topology, conserved domains, secondary structures, and responses to external signals. The brassinosteroid downstream genes in apple were, respectively, induced or repressed by five phytohormones. Furthermore, these apple downstream genes were differentially expressed in different apple grafting combinations ("Nagafu No. 2"/"Malling 9" and "Nagafu No. 2"/"Nagafu No. 2") and long–short shoot varieties ("Yanfu No. 6" and "Nagafu No. 2"). Responses of the MdBZR genes to diverse stress signals were examined and candidate hub genes were identified. These findings indicated that several brassinosteroid signaling downstream genes in Rosaceae functionally differed from their rice homologs, and certain apple genes may play roles in plant height and stress responses. This study provided valuable information and presented enriched biological theories on brassinosteroid signaling downstream genes in apple. Identification of such genes serve to help expand apple breeding and growth. This study provides useful information for brassinosteroid signaling downstream genes. [ABSTRACT FROM AUTHOR]

Phloridzin is a phenolic acid associated with the genus Malus (Mill.) that causes apple replant disease. The removal of phloridzin is of great significance to alleviate this condition, and hence biochar was investigated for this purpose. The goal of this study was to improve the adsorption capacity of biochar for phloridzin by chemical modification. Biochar from apple branches and biochar modified with chitosan to were characterized by elemental analysis, Brunauer Emmett Teller analysis, Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. Batch adsorption experiments were employed to select the optimal biochar dosage and adsorption time. The results showed that biochar treated for 24 h at 6 g L−1 achieved best adsorption properties and that the chitosan-modified biochar provided a higher adsorption capacity than the unmodified material. The influence of pH upon the adsorption was studied and the results were fitted with isotherm and kinetic equations. The results showed that adsorption process corresponds to a Langmuir isotherm and pseudo-second-order kinetics. The qmax of the biochar was increased from 15.93 to 28.96 mg g−1 by modification with chitosan. The pH was shown to play an important role in the adsorption process. The adsorption of phloridzin to biochar was demonstrated to be a single-layer multiple component adsorption process based on chemisorption. This study provides a theoretical basis to alleviate apple replant disease. [ABSTRACT FROM AUTHOR]

BACKGROUND: The host specificity of known Bacillus thuringiensis Cry and Vip pesticidal proteins still needs extensive investigation and the proteins currently used in crop protection are not effective against many pest species. Cydia pomonella (L.) is a widespread and economically important pest of apples, very difficult to control, since the larvae spend most of their life inside a fruit. Currently, large amounts of broad‐spectrum, detrimental synthetic agents are used to combat this herbivore and therefore biopesticides with high activity against C. pomonella are very much needed. RESULTS: The toxicity of B. thuringiensis Cry9Ea along with five distinct pesticidal proteins (Cry1Aa, Cry1Ca, Cry1Ia, Cry2Ab and Vip3Aa) has been determined towards the first‐instar larvae of C. pomonella. Cry9Ea has much higher activity than the remaining tested proteins (30–1200‐fold lower LC50) and possibly is the most potent B. thuringiensis pesticidal protein bioassayed against C. pomonella so far. In contrast, Cry9Ea is not toxic towards Spodoptera exigua (Hübn.), indicating a potentially narrow spectrum of activity. Both insect species show high variability in susceptibility to the remaining Cry/Vip proteins. CONCLUSIONS: The obtained results extend the existing knowledge regarding B. thuringiensis pesticidal protein host range and indicate Cry9Ea as a promising candidate for successful biological control of C. pomonella. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Summary: Co‐infection of apple trees with several viruses/viroids is common and decreases fruit yield and quality. Accurate and rapid detection of these viral pathogens helps to reduce losses and prevent virus spread. Current molecular detection assays used for apple viruses require specialized and expensive equipment. Here, we optimized a CRISPR/Cas12a‐based nucleic acid detection platform for the diagnosis of the most prevalent RNA viruses/viroid in apple, namely Apple necrotic mosaic virus (ApNMV), Apple stem pitting virus (ASPV), Apple stem grooving virus (ASGV), Apple chlorotic leaf spot virus (ACLSV) and Apple scar skin viroid (ASSVd). We detected each RNA virus/viroid directly from crude leaf extracts after simultaneous multiplex reverse transcription‐recombinase polymerase amplification (RT‐RPA) with high specificity. Positive results can be distinguished by the naked eye via oligonucleotide‐conjugated gold nanoparticles. The CRISPR/Cas12a‐RT‐RPA platform exhibited comparable sensitivity to RT‐qPCR, with limits of detection reaching 250 viral copies per reaction for ASPV and ASGV and 2500 copies for the others. However, this protocol was faster and simpler, requiring an hour or less from leaf harvest. Field tests showed 100% agreement with RT‐PCR detection for 52 samples. This novel Cas12a‐based method is ideal for rapid and reliable detection of apple viruses in the orchard without the need to send samples to a specialized laboratory. [ABSTRACT FROM AUTHOR]

Summary: Salt stress dramatically impedes plant growth and development as well as crop yield. The apple production regions are reduced every year, because of the secondary salt damage by improper fertilization and irrigation. To expand the cultivation area of apple (Malus domestica) and select salt‐resistant varieties, the mechanism of salt tolerance in apple is necessary to be clarified. The miR156/SPL regulatory module plays key roles in embryogenesis, morphogenesis, life cycle stage transformation, flower formation and other processes. However, its roles in the mechanisms of salt tolerance are unknown. In order to elucidate the mechanism of 156/SPL regulating salt stress in apple, we performed RLM‐5' RACE and stable genetic transformation technology to verify that both mdm‐MIR156a and MdSPL13 responded to salt stress in apple and that the latter was the target of the former. MIR156a overexpression weakened salt resistance in apple whereas MdSPL13 overexpression strengthened it. A total of 6094 differentially expressed genes relative to nontransgenic apple plants were found by RNA‐Seq analysis of MdSPL13OE. Further verification indicated that MdSPL13 targeted the MdWRKY100 gene promoter. Moreover, MdWRKY100 overexpression enhanced salt tolerance in apple. Our results revealed that the miR156/SPL module regulates salt tolerance by up‐regulating MdWRKY100 in apple. This study is the first to elucidate the mechanism underlying the miRNA network response to salt stress in apple and provides theoretical and empirical bases and genetic resources for the molecular breeding of salt tolerance in apple. [ABSTRACT FROM AUTHOR]

Summary: Changes in carbohydrates and organic acids largely determine the palatability of edible tissues of horticulture crops. Elucidating the potential molecular mechanisms involved in the change in carbohydrates and organic acids, and their temporal and spatial crosstalk are key steps in understanding fruit developmental processes. Here, we used apple (Malus domestica Borkh.) as research materials and found that MdbHLH3, a basic helix–loop–helix transcription factor (bHLH TF), modulates the accumulation of malate and carbohydrates. Biochemical analyses demonstrated that MdbHLH3 directly binds to the promoter of MdcyMDH that encodes an apple cytosolic NAD‐dependent malate dehydrogenase, activating its transcriptional expression, thereby promoting malate accumulation in apple fruits. Additionally, MdbHLH3 overexpression increased the photosynthetic capacity and carbohydrate levels in apple leaves and also enhanced the carbohydrate accumulation in fruits by adjusting carbohydrate allocation from sources to sinks. Overall, our findings provide new insights into the mechanism of how the bHLH TF MdbHLH3 modulates the fruit quality. It directly regulates the expression of cytosolic malate dehydrogenase MdcyMDH to coordinate carbohydrate allocation and malate accumulation in apple. [ABSTRACT FROM AUTHOR]

Colletotrichum fioriniae of the C. acutatum species complex is an important hemibiotrophic pathogen of vegetables and fruits in temperate regions worldwide. In apple, it is one of the primary species responsible for bitter rot disease. Understanding the disease cycle is complicated because many broadleaf plants can be hosts of C. fioriniae. By detecting and quantifying rain-splashed C. acutatum species complex conidia in more than 500 samples from heavily bitter-rot-infected apple orchards and nearby forested woodlots over two summers, we show that conidial quantities were higher in the woodlots than in the orchards. Testing of more than 1,000 surface-disinfected leaves of apple and 24 different forest plant species showed that overall C. fioriniae was an abundant leaf endophyte, with high variation in leaf colonization area. Endophytic isolates from leaves were pathogenic on apples, and multilocus sequence analysis showed 100% identity between most isolates from leaves and diseased fruits. Apple leaves endophytically infected with C. fioriniae were present in a conventionally managed orchard and abundant in an untreated orchard. These lines of evidence, in the context of previously published research, lead us to hypothesize that the main ecological role of C. fioriniae is that of a leaf endophyte, which we present as a generalized C. fioriniae infection cycle that provides an updated framework for its integrated management in agricultural systems. [ABSTRACT FROM AUTHOR]

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BACKGROUND: Fruit softening is a major determinant of commercial value and shelf life. A transcriptomic analysis of 'Golden Delicious' and 'Golden Del. Reinders' (a bud mutation of 'Golden Delicious' that readily softens) apple fruit was conducted during storage. RESULTS: A comparative analysis of the obtained expression profiles of fruit between two cultivars identified 1345 upregulated and 3475 downregulated differentially expressed genes (DEGs). The DEGs identified were associated with cellular processes and carbohydrate metabolism and were especially enriched in cell‐wall‐related genes. Among the cell‐wall‐related genes, the xyloglucan endotransglucosylase/hydrolases (XTH) gene MdXTHB was significantly upregulated and exhibited high expression levels in 'Golden Del. Reinders' fruit, which had a lower level of firmness relative to 'Golden Delicious'. Overexpression of MdXTHB in both 'Golden Delicious' and 'Fuji', which typically maintain high levels of firmness in storage, exhibited faster rates of softening and an earlier peak of ethylene production than empty‐vector‐infiltrated fruit did. CONCLUSION: The results of this study indicate that MdXTHB potentially promotes apple fruit softening by degrading the fruit cell wall. This result is also useful to designing further experiments on the molecular regulation of fruit softening in apple. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Background: Soil salinity is a critical threat to global agriculture. In plants, the accumulation of xanthine activates xanthine dehydrogenase (XDH), which catalyses the oxidation/conversion of xanthine to uric acid to remove excess reactive oxygen species (ROS). The nucleobase-ascorbate transporter (NAT) family is also known as the nucleobase-cation symporter (NCS) or AzgA-like family. NAT is known to transport xanthine and uric acid in plants. The expression of MdNAT is influenced by salinity stress in apple. Results: In this study, we discovered that exogenous application of xanthine and uric acid enhanced the resistance of apple plants to salinity stress. In addition, MdNAT7 overexpression transgenic apple plants showed enhanced xanthine and uric acid concentrations and improved tolerance to salinity stress compared with nontransgenic plants, while opposite phenotypes were observed for MdNAT7 RNAi plants. These differences were probably due to the enhancement or impairment of ROS scavenging and ion homeostasis abilities. Conclusion: Our results demonstrate that xanthine and uric acid have potential uses in salt stress alleviation, and MdNAT7 can be utilized as a candidate gene to engineer resistance to salt stress in plants. [ABSTRACT FROM AUTHOR]

Background: In plants, CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1) is a key negative regulator in photoperiod response. However, the biological function of COP1-interacting protein 1 (CIP1) and the regulatory mechanism of the CIP1-COP1 interaction are not fully understood. Results: Here, we identified the apple MdCIP1 gene based on the Arabidopsis AtCIP1 gene. Expression pattern analysis showed that MdCIP1 was constitutively expressed in various tissues of apple, and responded to stress and hormone signals at the transcriptional level. Ectopic expression of MdCIP1 complemented the phenotypes of the Arabidopsis cip1 mutant, and MdCIP1 inhibited anthocyanin biosynthesis in apple calli. In addition, the biochemical assay demonstrated that MdCIP1 could interact with MdCOP1 protein by their coiled-coil domain, and MdCIP1-OX/cop1–4 had a similar phenotype in photomorphogenesis with the cop1–4 mutant, suggesting that COP1 is epistatic to CIP1. Furthermore, the transient transformation assay indicated that MdCIP1 repressed anthocyanin biosynthesis in an MdCOP1-mediated pathway. Conclusion: Take together, this study finds that MdCIP1 acts as a repressor in regulating hypocotyl elongation and anthocyanin biosynthesis through MdCOP1 in apple. [ABSTRACT FROM AUTHOR]

Fruit shape is the result of the interaction between genetic, epigenetic, environmental factors and stochastic processes. As a core biological descriptor both for taxonomy and horticulture, the point atwhich shape stability is reached becomes paramount in apple cultivar identification, and authentication in commerce. Twelve apple cultivars were sampled at regular intervals from anthesis to harvest over two growing seasons. Linear and geometric morphometrics were analysed to establish if and when shape stabilised and whether fruit asymmetry influenced this. Shape stability was detected in seven cultivars, four asymmetric and three symmetric. The remaining five did not stabilise. Shape stability, as defined here, is cultivar-dependent, andwhen it occurs, it is late in the growing season. Geometric morphometrics detected stability more readily than linear, especially in symmetric cultivars. Key shape features are important in apple marketing, giving the distinctness and apparent uniformity between cultivars expected at point of sale. [ABSTRACT FROM AUTHOR]

Extensive use of simple sequence repeat (SSR) is facilitated if loci would be transferable across species even in closely related genera to overcome high cost and efforts involved in their development as major constraints. In the present study, apple and pear genomic microsatellite primer pairs were used to amplify SSR loci in apple, pear, quince and loquat genotypes, respectively. Already reported SSRs were selected based on their polymorphic survey for successful amplification with at least one polymerase chain reaction (PCR) product of the approximate size expected for a homologous locus screened among apple and pear genotypes for further transferability exploration across other temperate pome fruit crops, respectively. Highest transferability of apple and pear SSR, 61.53 % and 73.33 % was observed in closely related quince and apple genotypes, respectively. This indicated that primer binding sites between these two closely related genera, Malus and Pyrus, are fairly well conserved. Maximum transferability rate was found to be 93.33 % and 80.00 % across all the subjected genotypes for primer CH05D11 and TSUenh016 in apple and pear, respectively. The transferability of markers is based on genomic similarity, and can reflect the relationship of genome collinearity and even evolution between species. This high level of transferability of apple and pear SSRs to other temperate pome fruit crops indicated their promise for application to future molecular screening, map construction, and comparative genomic studies, etc. [ABSTRACT FROM AUTHOR]

In 2014-2017 an investigation was carried out into the occurrence of fungal storage diseases of five apple varieties (Red Jonaprince, Gala, Golden Delicious, Gloster and Ligol) in the Sandomierz orchard region. The fruit was stored at a CA cold storage room with ULO controlled atmosphere for six months. Occurrence of eight storage diseases was found. The most frequently occurring disease was bull's eye rot and the losses caused thereby were even 24% of the affected fruit. The cultivars most susceptible to this disease were the 'Golden Delicious' and 'Ligol' apples; the least susceptible were the 'Gloster' ones. The apples were significantly less affected by the fungi that cause brown rot, grey mould rot, blue mould rot and apple scab. Very seldom were the symptoms of calyx end rot, mouldy core and core rot, and anthracnose. Varying severity of infection of the varieties was noted in each season of observation. [ABSTRACT FROM AUTHOR]

Columnar growth in apples can have considerable positive consequences for orchard maintenance, but the lack of columnar cultivars producing fruits with desired market quality prevents their broader utilization in orchards. New crossings focused on their breeding are therefore conducted throughout the world every year. Unfortunately, the reliable discrimination between columnar growth and normal phenotype is difficult until seedlings are 2–3 years of age. However, molecular marker–assisted selection (MAS) can be used in seedlings several weeks old providing immense help in breeding programmes focused on columnar apple production. Here, we describe a rapid and reliable method for the detection of both wild‐type (WT) and columnar (Co) alleles originating from 'McIntosh Wijcik' in a single reaction using a real‐time PCR allelic discrimination approach. Our assay was tested in 130 genotypes (80 normal and 50 columnar habit) from various crossings and their parents, and in all cases, genotype corresponded to phenotype. The assay is thus suitable for laboratories interested in high‐throughput MAS for columnar tree habit breeding. [ABSTRACT FROM AUTHOR]

Gymnosporangium species (Pucciniaceae, Pucciniales, Basidiomycota) are the causal agents of cedarapple rust diseases, which can lead to significant economic losses to apple cultivars. Currently, the genus contains 17 described species that alternate between spermogonial/aecial stages on Malus species and telial stages on Juniperus or Chamaecyparis species, although these have yet to receive a modern systematic treatment. Furthermore, prior studies have shown that Gymnosporangium does not belong to the Pucciniaceae sensu stricto (s.str.), nor is it allied to any currently defined rust family. In this study we examine the phylogenetic placement of the genus Gymnosporangium. We also delineate interspecific boundaries of the Gymnosporangium species on Malus based on phylogenies inferred from concatenated data of rDNA SSU, ITS and LSU and the holomorphic morphology of the entire life cycle. Based on these results, we propose a new family, Gymnosporangiaceae, to accommodate the genus Gymnosporangium, and recognize 22 Gymnosporangium species parasitic on Malus species, of which G. lachrymiforme, G. shennongjiaense, G. spinulosum, G. tiankengense and G. kanas are new. Typification of G. asiaticum, G. fenzelianum, G. juniperi-virginianae, G. libocedri, G. nelsonii, G. nidus-avis and G. yamadae are proposed to stabilize the use of names. Morphological and molecular data from type materials of 14 Gymnosporangium species are provided. Finally, morphological characteristics, host alternation and geographical distribution data are provided for each Gymnosporangium species on Malus. [ABSTRACT FROM AUTHOR]

Malus hupehensis is an extensively used apple rootstock in China. In the current study, M. hupehensis seedlings were treated with exogenous 2.2 µm 6‐benzyladenine (6‐BA) so as to investigate the mechanism by which 6‐BA affects lateral root development.The results indicate that 6‐BA treatment promotes elongation and thickening of both root and shoot in M. hupehensis, but reduces the number of lateral roots, as well as reducing the auxin level after 6‐BA treatment. Moreover, MhAHK4, MhRR1 and MhRR2 were also significantly up‐regulated in response to 6‐BA treatment.Expression levels of auxin synthesis‐ and transport‐related genes, such as MhYUCCA6, MhYUCCA10, MhPIN1 and MhPIN2, were down‐regulated, which corresponds with lower auxin levels in the 6‐BA‐treated seedlings. A negative regulator of auxin, MhIAA3, was induced by 6‐BA treatment, leading to reduced expression of MhARF7 and MhARF19 in 6‐BA‐treated seedlings. As a result, expression of MhWOX11, MhWOX5, MhLBD16 and MhLBD29 was blocked, which in turn inhibited lateral root initiation.In addition, a lower auxin level decreased expression of MhRR7 and MhRR15, which repressed expression of key transcription factors associated with root development, thus inhibiting lateral root development. In contrast, 6‐BA treatment promoted secondary growth (thickening) of the root by inducing expression of MhCYCD3;1 and MhCYCD3;2. Collectively, the changes in hormone levels and gene expression resulted in a reduced number of lateral roots and thicker roots in 6‐BA‐treated plants. [ABSTRACT FROM AUTHOR]

Among the postharvest pathogens of apple fruit, Penicillium expansum (P.expansum) is considered to be one of the most common fungal pathogens worldwide. It is the causal agent of blue mold decay; the main serious economically disease of apple fruits, and the main producer of patulin (PAT). The principal objective of this work was to evaluate the aggressiveness and the PAT production of three isolated strains from apples produced in the East of Algeria. These strains were isolated then screened for their inhibitory activity against Escherichia coli and Bacillus subtilis (18 mm and 18 mm for S7; 10 mm and 11mm for S3), as well as their ability to cause blue rot (S4). The three strains S7, S3, and S4 (MN904448, MT023795 and MN904449, respectively) were identified as P. expansum by ITS1, ITS4, and ß-tubulin gene sequences analysis. The in vitro ability to produce PAT was confirmed by Gas chromatography-mass spectrometry of strains' crude extracts cultured on YES (Yeast-Extract-Sucrose) medium. Indeed, these strains exhibited a great capacity to cause blue mold decay for all tested apples (26 to 52 mm lesion diameter), after nine days of incubation at 25°C. Apples rotten area analysis that was performed by UPLC analysis revealed that these three strains were able to produce PAT at different concentrations ranging from 0.57 to 469 µg/mL. Thus, these strains constitute a risk to consumer health because these amounts exceed the permissive level of PAT. [ABSTRACT FROM AUTHOR]

The local plant genetic resources of Malus sp. in the pre-Balkan region of the town of Troyan were studied. Eight cultivars and forms from the group of the early ripening apples were studied. The following more widespread types were specified: ‚Vista Bella’, ‘Mollies Delicious’, ‘Prima’, forms of the group of ‘Petrovki’, ‘Byala ranna’ and ‘Chervena ranna’. Their main morphological characteristics were studied: height, diameter, stalk length, colouring, biochemical analysis, fruit taste. Most of them have increased resistance to the main apple diseases, which allows their cultivation without the application of plant protection and makes them suitable for organic fruit production. [ABSTRACT FROM AUTHOR]

Apple, as one of the most important economic forest tree species, is widely grown in the world. Abiotic stresses, such as high salinity and iron deficiency, affect apple growth and development. WRKY transcription factors (TFs) are widely involved in the responses of plants to adverse stresses. In the present study, a new WRKY gene was isolated from Malus xiaojinensis and designated as MxWRKY55. Subcellular localization showed that MxWRKY55 was localized to the nucleus. The expression level of MxWRKY55 was highly affected by salt, low-Fe, and high-Fe stresses in M. xiaojinensis seedlings. When MxWRKY55 was introduced into Arabidopsis thaliana, it greatly enhanced the salt and Fe tolerance. When dealt with high- and low-Fe stresses, the overexpression of MxWRKY55 in transgenic A. thaliana resulted in higher levels of root length and fresh weight as well as contents of chlorophyll and Fe than wild type (WT). Increased expression of MxWRKY55 in transformed A. thaliana also contributed to higher contents of chlorophyll and proline and higher activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), while malondialdehyde (MDA) content was lower, especially in response to salt stress. Therefore, these results show that MxWRKY55 plays a positive role in the process of plant resistance to salt, low-Fe, and high-Fe stresses. [ABSTRACT FROM AUTHOR]

Venturia inaequalis is a notorious fungal pathogen and show classical gene for gene interaction with its apple host. Neutral markers provide clues about history, evolutionary potential, genetic diversity and population structure of V. inaequalis. The genetic diversity and population structure of fungus indicates that the pathogen is highly diverse with the capacity to breach the scab resistance genes. In the present study, we collected 108 V. inaequalis isolates from three apple cultivars differing in Rvi1 resistance gene. Based on the AMOVA, the variation was mostly distributed among the isolates, providing evidence of non-existence of subpopulation in orchards thus founder population is difficult to arise in Kashmir apple orchards. Pair wise genetic differentiation is less due to regular occurrence of gene flow between the populations residing on different orchard as infected material is transported without stringent quarantine measures. Based on principal coordinate analysis and clustering algorithm as implemented in STRUCTURE, we observed admixture between the two subpopulations, which is quite low, suggesting the existence of pre-zygotic and post-zygotic barriers to gene flow and we cannot rule out the existence of other structures shared by accessions belonging to different varieties. Due to the continuous increase in introduction and monoculture of apple varieties, mixed orchard with different host resistance specificities are more suitable for managing the apple scab in Kashmir valley. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the application of CaCO3 in liquid formulation on the incidence of sunburn and the visual quality of apples, as well as to test application times and dosages of biostimulants in increasing the red Color of the fruits. The study was carried out in partnership with the rural producer, in the orchards located in the municipality of Fraiburgo-SC, in the 2018/2019 harvest. To meet the proposed objectives, two different experiments were conducted: experiment 1 - application of calcium carbonate to reduce the incidence of sunburn in apples and experiment 2 - use of biostimulant to increase the red Color in the epidermis of apples. The variables analyzed were: production data (kg plant-1, fruits plant-1, average fruit mass and aspects related to fruit quality: pulp firmness, soluble solids content, mineral content in fruits, percentage of red Color in the epidermis of the fruits and incidence of sunburn. The tests carried out to promote the red Color of the fruits showed satisfactory results. However, the tests developed aiming at reducing the incidence of sunburn did not show reliable results, since the environmental conditions, mainly the sunstroke, were not favorable to the development of the damage to the fruits, making it impossible to obtain conclusive information on the efficiency of the CaCO3 product. in reducing the incidence of sunburn in apples. The application of CaCO3 as a sunscreen does not improve the calcium content of the harvested fruits. The application of Physiogrow® Color promotes better allocation of the harvested fruits in categories of greater coloration of the epidermis. [ABSTRACT FROM AUTHOR]

In a two-year study, the effects of three training systems on apple fruit and leaf parameters: 9 fruit yield, 8 physicochemical and 4 antioxidant capacity related parameters and the relationships among 11 yield quality parameters, of the apple cultivar 'Royal Gala' were studied. In addition, light penetration into the tree canopy was determined. The investigated three training systems were Oblique Palmette (1250 trees ha-1), Bibaum (1923 trees ha-1) and Slender Spindle (1666 trees ha-1). Light penetration into the tree canopy, fruit number per tree, fruit weight, fruit yield, fruit skin colour, fruit firmness, starch index of fruit, N- and K-contents of leaves as well as ascorbic acid content, total anthocyanins and total antioxidant capacity of fruit indicated significant differences (P < 0.05) amongst the training systems, but the differences were not significant between experimental years. The Bibaum gave the highest values for light penetration into the tree canopy, fruit number per tree, fruit yield, fruit skin colour, starch index of fruit, N- and K-contents of leaves and total anthocyanins, which were significantly different from those of the Oblique Palmette or the Slender Spindle. The Slender Spindle gave the highest values for fruit weight, fruit firmness and total antioxidant capacity, which were significantly different from those of the Bibaum. Fruit of the Oblique Palmette trained trees showed the highest ascorbic acid content, which was significantly different from that of the Slender Spindle but not from the Bibaum. From the 55 correlation pairs of each training system, 27, 17 and 15 were significant at P < 0.05 in the Oblique Palmette, the Bibaum and the Slender Spindle, respectively. Only five correlation pairs were significant in all the three training systems. This study clearly demonstrated that most of the parameters were largely affected by the training systems, which may influence apple growing practices and fruit quality in a given orchard training system. [ABSTRACT FROM AUTHOR]

Salt stress is an important environmental factor affecting the growth and production of agricultural crops and fruits worldwide, including apple (Malus × domestica). In this study, we demonstrate that a salt-responsive MYB transcription factor (TF), designated as MdMYB63, promotes survival under salt stress. Overexpression of MdMYB63 in apple calli significantly enhanced salt tolerance. Screening of the AP2/ERF family of TFs identified MdERF106 as an interaction partner of MdMYB63. Further analyses showed that the MdMYB63–MdERF106 complex significantly promotes the expression of downstream MdSOS1 , thereby improving the Na+ expulsion and salt tolerance of apple. These functional analyses of MdMYB63 have provided valuable insights into the regulatory network of salt tolerance, and lay a theoretical foundation for the cultivation of new salt-tolerant apple varieties. • Functional analyses of MdMYB63 provide valuable insights into the salt tolerance. • Overexpression of MdMYB63 in apple calli promotes its survival under salt stress. • MdMYB63 binds to MBS on the promoter of MdSOS1 to enhance its transcription. • MdERF106 can significantly promote the effect of MdMYB63 on the expression of downstream MdSOS1 by forming a protein complex. • MYBs can directly regulate SOS1 to participate in the salt tolerance of plants. [ABSTRACT FROM AUTHOR]

The local plant resources of Malus sp. in the Fore Balkan region of Troyan town – the villages Beli Osam, Shipkovo, Chiflik were studied. The more wide- spread cultivars and forms of apples were established: Canadian Reinette, Yellow Belle Fleur, Winter green, forms of the groups of Perusha, Shekerka, Belurka, Tziganka, Troyanka. The main morphological characteristics of the fruits of 5 selected large-fruited genotypes from deserving greater attention were studied: weight, shape, colouration, pedicel length and palatability of fruits. Most of them have increased resistance of the main apple diseases, which allows their cultivation without applying plant protection and make them suitable for organic fruit production. [ABSTRACT FROM AUTHOR]

Accurate recognition of green fruit targets is one of the key technologies for fruit growth monitoring and yield estimation. To solve the problem of fruit misidentification due to the similarity between fruit skin and leaf colors, a progressive detection method of green apples in natural environments was proposed. Image enhancement based on fuzzy set theory was carried out to make the fruit targets more salient in the whole image. Then, the fruit areas were roughly determined by the attention-based information maximization (AIM) algorithm, and the recognized apple regions were cropped according to the adaptive pixel-extending method to remove the background information. After that, accurate segmentation of fruit targets was accomplished by fusing the illumination-invariant image and R-component of the cropped image. To evaluate the performance of this method, it was compared with the illumination invariance theory-based algorithm, mean shift algorithm, K-means clustering algorithm, manifold ranking algorithm and GrabCut algorithm. The test was conducted using 200 green apple images under different growth statuses. Experimental results showed that the segmentation rate of the proposed method was 86.91%, which was 3.26%, 6.35%, 16.43%, 3.08% and 4.7% higher than those of the other five methods, respectively. The false positive rate and false negative rate were 0.88% and 10.53%, which gained an advantage over those of the other five segmentation algorithms. The localization error was 3.65%. In conclusion, the proposed method can accurately segment green fruit targets, which can lay the foundation for intelligent management of fruits over the entire growing season. [ABSTRACT FROM AUTHOR]

Apple and pear scab are foliar diseases of ornamental and fruiting apple and pear trees. Unmanaged, yield and aesthetic losses can be severe. Overreliance on synthetic fungicides means novel means of disease management are required. Field trials were conducted using apple (Malus cv. Crown Gold) and pear (Pyrus communis 'Williams Bon Chrétien') to assess the efficacy of a range of commercially available inducing resistance (IR) agents (harpin protein, potassium phosphite, salicylic acid derivative, and chitosan) as root drenches against both scab diseases. A synthetic fungicide (penconazole) spray program used within the UK for apple and pear scab control was included for comparison. Each IR agent was applied four times, (i) before the visible appearance of scab (April through June, i.e., preventatively) or (ii) after symptoms of scab were visibly observed (June through August, i.e., curatively). Limited efficacy as scab protectants was demonstrated when IR agents were applied curatively. Likewise, limited efficacy was recorded when IR agents were applied once or twice as a preventative measure. However, when IR agents were applied as root drenches greater or equal to three times, efficacy as scab protectants was confirmed (increased leaf chlorophyll content, increased fruit yield, reduced leaf and fruit scab severity). A synthetic fungicide penconazole spray program provided the greatest protection against apple and pear scab in all trials when sprayed preventatively rather than curatively. Results suggest application of at least three root drenches from April through June with an appropriate IR agent provides a useful addition to existing methods of apple and pear scab management under field conditions. [ABSTRACT FROM AUTHOR]

In order to detect the soluble solids content of apples quickly and accurately, a portable apple soluble solids content detector based on USB2000 + micro spectrometer was developed. The instrument can communicate with computer terminal and mobile app through network port, Bluetooth and other ways, which can realize the rapid acquisition of apple spectral information. Firstly, the visible / near-infrared spectrum data and soluble solids content information of 160 apple samples were collected; secondly, the spectral data preprocessing methods were compared, and the results showed that the prediction model of sugar content based on partial least square (PLS) method after average smoothing preprocessing was accurate. The correlation coefficient (RP) and root mean square error (RMSEP) of the prediction model were 0.902 and 0.589 ° Brix, respectively. Finally, on the basis of average smoothing preprocessing, competitive adaptive reweighted sampling (CARS) and successive projections algorithm (SPA) were used to optimize the wavelength of spectral data, and PLS model was constructed based on the selected 17 characteristic wavelengths, which can increase the accuracy of soluble solids content prediction model, increase the RP to 0.912, and reduce RMSEP to 0.511 ° Brix. The portable visible / near infrared spectrum soluble solids prediction model based on the instrument and method has high accuracy, and the detector can quickly and accurately measure the soluble solids content of apple. [ABSTRACT FROM AUTHOR]

The present study investigated how different storage conditions affect antioxidant levels in three scab-resistant and powdery mildew-tolerant apple cultivars. The contents of carotenoids, along with free and glycosylated phenolic acids, were quantified in harvested apples and apples stored in boxes with controlled atmospheric conditions (1.2% O2 and 2.2% CO2) and temperature (1 °C), boxes with regulated temperature (1 °C) and storage rooms with a temperature between 1 and 4 °C. All three cultivars demonstrated a continuous decrease in total carotenoid content (sum of ß-carotene, lutein, neoxanthin, violaxanthin, zeaxanthin and antheraxanthin) during the storage period. However, apples stored under controlled atmospheric conditions showed significantly higher carotenoid levels than apples stored under other approaches over 3 and 5 months of storage. Although the storage approach clearly affected carotenoid levels across the three tested cultivars, the ratio between the levels of individual carotenoids was neither affected by storage approach nor cultivar. Free phenolic acid contents were found to be cultivar specific; whereas, all three cultivars demonstrated similar glycosylated phenolic acid contents. Chlorogenic acid was the most common free phenolic acid in all three cultivars, while protocatechuic and caffeic acid were the dominant glycosylated phenolic acids identified from the cultivars. Interestingly, stored apples showed higher free phenolic acid levels than harvested apples; while, both harvested and stored apples showed similar concentrations of glycosylated phenolic acids. As such, none of the three tested storage conditions had a pronounced effect on either group of phenolic acids (total content or concentrations of individual compounds). [ABSTRACT FROM AUTHOR]