scholarly journals Bacterial Endophyte Community Dynamics in Apple (Malus domestica Borkh.) Germplasm and Their Evaluation for Scab Management Strategies

2021 ◽  
Vol 7 (11) ◽  
pp. 923
Author(s):  
Shahid A. Padder ◽  
Sheikh Mansoor ◽  
Sajad A. Bhat ◽  
Tawseef Rehman Baba ◽  
Rauoof Ahmad Rather ◽  
...  
Keyword(s):  
Community Dynamics ◽  
Venturia Inaequalis ◽  
Disease Incidence ◽  
Management Strategies ◽  
Apple Scab ◽  
Alpha Diversity ◽  
Diversity Indices ◽  
Apple Varieties ◽  
Bacterial Endophyte ◽  
Endophyte Community

The large genetic evolution due to the sexual reproduction-mediated gene assortments and propensities has made Venturia inaequalis (causing apple scab) unique with respect to its management strategies. The resistance in apple germplasm against the scab, being controlled for by more than fifteen genes, has limited gene alteration-based investigations. Therefore, a biological approach of bacterial endophyte community dynamics was envisioned across the apple germplasm in context to the fungistatic behavior against V. inaequalis. A total of 155 colonies of bacterial endophytes were isolated from various plant parts of the apple, comprising 19 varieties, and after screening for antifungal behavior followed by morphological, ARDRA, and sequence analysis, a total of 71 isolates were selected for this study. The alpha diversity indices were seen to fluctuate greatly among the isolation samples in context to microflora with antifungal behavior. As all the isolates were screened for the presence of various metabolites and some relevant genes that directly or indirectly influence the fungistatic behavior of the isolated microflora, a huge variation among the isolated microflora was observed. The outstanding isolates showing highest percentage growth inhibition of V. inaequalis were exploited to raise a bio-formulation, which was tested against the scab prevalence in eight apple varieties under controlled growth conditions. The formulation at all the concentrations caused considerable reductions in both the disease severity and disease incidence in all the tested apple varieties. Red Delicious being most important cultivar of the northwestern Himalayas was further investigated for its biochemical behavior in formulation and the investigation revealed different levels of enzyme production, chlorophyll, and sugars against the non-inoculated control.

scholarly journals Development of the antioxidant indexes (FRAP, TFC, TPC) of scabbing resistant apple varieties in storage

2020 ◽  
pp. 89-94
Author(s):  
Mihály Orosz-Tóth ◽  
Sándorné Kincses
Keyword(s):  
Nutritional Value ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Apple Fruit ◽  
Bioactive Substances ◽  
Total Polyphenol ◽  
Apple Variety ◽  
Apple Varieties ◽  
Apple Production ◽  
The Given

One of the most important groups of bioactive substances in apples are antioxidants, which have a health-preserving effect. The amount of these compounds varies not only during the ripening of the apple fruit, but also continuously during post-harvest storage. A growing group of health-conscious consumers are looking for apple varieties with a nutritional value that satisfies their needs. In the scope of our research, we examined 5 apple varieties originating from the Derecske horticultural site of KITE cPlc. in 2016. The plantation was planted to be suitable for intensive apple production. Samples were collected at the time of maturity (August-October) of the given variety. The 5 examined apple varieties (Gaia, Isaaq, Modí, Smeralda and Fujion) are all resistant to apple scab (fungal disease caused by Venturia inaequalis). The 2-month storage experiment was conducted at 16–17 °C, which had an aggressive effect on our stored apples. Total polyphenol (TPC) and flavonoid (TFC) content as well as FRAP values of the apples were measured. Measurements were taken immediately after harvest and after 1 and 2 months of storage. Our results were evaluated by using the IBM SPSS Statistics 20 software. Our aim was to compare the antioxidant results of 5 scab-resistant apple varieties, which change continuously during storage. The antioxidant content of our apple varieties increased during 2 months storage. The best result was achieved by the Modí apple variety (FRAP: 467.32 mg/100g; TFC: 317.76 mg/100g; TPC: 1771.97 mg/100g). Consumers may want to consume apples stored for a longer period of time if they are to absorb large amounts of antioxidants.

scholarly journals Disease progress of apple scab caused by Venturia inaequalis in environmentally friendly growing systems

2000 ◽  
Vol 6 (4) ◽  
Author(s):  
I. J. Holb
Keyword(s):  
Regression Analysis ◽  
Linear Regression ◽  
Venturia Inaequalis ◽  
Disease Incidence ◽  
Linear Regression Analysis ◽  
Apple Scab ◽  
Integrated System ◽  
Organic System ◽  
Disease Progress ◽  
Leaf Disease

Progression of apple scab epidemic in six apple cultivars, including two current and susceptible (Gala Must, Elstar), two old (Egri Piros, Darusóvári), and two resistant cultivars (Relinda, Releika), were described and analysed in a two-year-study, in two environmental-friendly growing systems (organic and integrated). Curves of disease progress, linear regression analysis of transformed disease incidence data and Area Under Disease Progress Curves (AUDPC) were used to characterise the epidemic processes of the selected cultivars. Cumulative disease progress curves showed continuous but asymmetrical scab development on the moderate or highly susceptible cultivars Gala Must, Elstar and Egri Piros, and on the tolerant or resistant cultivar Darusóvári and Relinda, in both systems. The cultivar Releika showed no symptoms either on fruit or leaf. In linear regression analysis, the best linearisation was given by logistic transformation. Adequate parameters leaf disease incidence rate, of obtained from a regression equation, were higher in the organic system than in the integrated system. Values of AUDPC showed great differences in leaf disease incidences among cultivars and between growing systems. AUDPC gave more differences for comparison of progresses of disease epidemic than growth rate of disease in different systems of disease control. Moreover, the obtained results were compared with similar studies on different pathosystems, and biological interpretations of the analyses are discussed below.

scholarly journals First Report of Atypical Scab Caused by Venturia asperata on Apple in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Yang Zhou ◽  
Haidong Bu ◽  
Chingchai Chaisiri ◽  
Qin Tan ◽  
Li Wang ◽  
...  
Keyword(s):  
Venturia Inaequalis ◽  
Disease Incidence ◽  
Large Subunit ◽  
Apple Scab ◽  
Agar Plate ◽  
Single Spore ◽  
First Report ◽  
Sequence Identity ◽  
Blast Analysis ◽  
Plastic Bag

Apple cv. ‘Huangtaiping’ (Malus pumila Mill.) is grown widely in northern China for the production of jellies, preserves, and cider. In 2018, atypical scab symptoms were observed on fruits of Huangtaiping in Heilongjiang Province of China. The disease incidence was estimated at approximately 0.4%. Symptoms were scab-like black spots (3 to 5 mm diam.) distinct from scab caused by Venturia inaequalis. Conidia were generally produced on lesions and using a modified microscope (Goh 1999), a single spore was picked up from each sample on water agar plate with a glass needle and then transferred to PDA amended with lactic acid (0.50 ml/L) and sulfate streptomycin (0.20 g/L). Fifteen isolates were obtained and incubated at 21°C for 6 weeks in darkness on PDA. The colonies on PDA were gray-black with circular morphology and floccose texture, which were similar with the characteristics of V. asperata described previously (Turan et al. 2019). The conidia were cylindrical to fusiform, 0 to 1 septate, yellowish and 19.7 (13.5 to 25.8) × 5.7 (3.6 to 6.9) μm (n = 10) in size, which were larger than previously described ones (Turan et al. 2019). DNA of three randomly selected isolates were extracted by a modified SDS method (Ping et al. 2004). The internal transcribed spacer (ITS) region of rDNA of the three selected isolates was amplified with the primers ITS4/ITS5 (White et al. 1990), sequenced and deposited in GenBank (MN958665, MN95866 and MN958667). BLAST analysis showed that the amplified sequences were identical and had 99.3% sequence identity with V. asperata (AF333447, MT459450 and MT459451), 95.4% sequence identity with V. cerasi (MK810963 and MK810964) and 94.3% sequence identity with V. carpophila (MN958609, MN958610 and MN958611). In addition, the complete large subunit ribosomal RNA gene (LSU) was amplified with the primers LROR/LR5 (Vilgalys and Hester 1990), sequenced and deposited in GenBank (MT845787, MT845788 and MT845789). BLAST analysis showed that the amplified sequences were identical and had 99.7% sequence identity with V. asperata (EF114711), 99.2% identity with V. carpophila (MT772296, MT845732 and MT845733 ) and 98% identity with V. cerasi (MK810848 and MK810849). Phylogenetic analysis based on concatenated ITS and LSU sequences showed that the tested isolates grouped with V. asperata strain 2349 in the same clade and the closest species with V. asperata was V. carpophila, followed by V. cerasi. In July 2019, pathogenicity of the isolate VAHLJ3-1-1 was evaluated on Huangtaiping. A conidia suspension with a concentration of 5×105/ml was sprayed evenly on the surface of six fruits. In order to maintain high humidity, inoculated fruits were wrapped with a plastic bag (a cotton ball with water was placed in the plastic bag) to maintain wetness for 3 days. Six fruits sprayed with water were used as a control. Four weeks after inoculation, similar symptom of atypical scab was observed on fruits of Huangtaiping, and V. asperata was isolated again from six inoculated fruits with reisolation frequency of 100% by the single spore isolation, while no symptom was observed on the control fruits. Based on the morphological and molecular identifications, the causal agent of atypical scab on Huangtaiping was identified as V. asperata. Apple scab is usually caused by V. inaequalis (Shen et al. 2020). However, apple scab has also been caused by V. asperata in Italy and France (Caffier et al. 2012; Turan et al. 2019). To the best of our knowledge, this is the first report of V. asperata associated with apple scab-like lesions in China. This information augments our knowledge of the spectrum of Venturia species associated with disease on apple fruit and will be a valuable foundation underpinning management strategies for this cultivar.

DNA MARKING WHEN CREATING APPLE VARIETIES WITH STABLE SCAB RESISTANCE

2020 ◽  
pp. 94-99
Author(s):  
М.I. Dulov ◽  
Keyword(s):  
Resistance Genes ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Genetic Resistance ◽  
Scab Resistance ◽  
Apple Breeding ◽  
Apple Varieties ◽  
Pcr Product ◽  
Fruit Flavor ◽  
New Generation

The use of chemical means of protection against Apple scab is associated with high material costs and causes great harm to the environment. Growing of apple varieties with stable resistance to scab (the pathogen Venturia inaequalis) will significantly limit the use of pesticides. On the territory of the Russian Federation, the Rvi6 gene is considered immune, which determines resistance to five scab races, including the most aggressive fifth. The country has scabimmune apple varieties created by scientists from VNIISPK, NCFSCHWWG, FRC named after I. V. Michurin , VSTISP and other scientific institutions. In recent years, the Rvi6 gene has been overcome by scab in many European countries, and the Rvi5 gene, which is immune to four scab races, has been overcome in Russia and Germany. When creating high-yielding apple varieties of a new generation, with good fruit flavor quality, long-term and stable resistance to scab, in addition to the rvi6 resistance gene, the most promising sources are the Rvi5, Rvi11, Rvi12, Rvi14 and Rvi15 genes. The Rvi2, Rvi4, Rvi6, Rvi7 and Rvi9 genes in the apple breeding process are best used in extended pyramids of genetic resistance to scab. This will allow you to combine several scab resistance genes that control the immune system in one apple genotype. The article describes the characteristics of DNA markers, the nucleotide sequence of primers, the size of target fragments of the PCR product, including the size of the dominant allele product for detecting Rvi genes of the Venturia inaequalis pathogen that are promising for apple breeding in varieties and hybrid material. Amplification programs were selected to identify resistance genes to various races of apple scab.

scholarly journals Effect of Leaf Wetness Duration, Temperature, and Conidial Inoculum Dose on Apple Scab Infections

Plant Disease ◽  
1999 ◽  
Vol 83 (6) ◽  
pp. 531-534 ◽  
Author(s):  
J. R. Hartman ◽  
L. Parisi ◽  
P. Bautrais
Keyword(s):  
Venturia Inaequalis ◽  
Disease Incidence ◽  
Apple Scab ◽  
The Other ◽  
Leaf Wetness ◽  
Leaf Wetness Duration ◽  
Inoculum Dose ◽  
Golden Delicious ◽  
Wetness Period ◽  
Series Of Experiments

Apple seedlings (2 months old, ‘Idared’ × ‘Golden Delicious’) were inoculated with conidia of Venturia inaequalis in order to study the effects of inoculum dose and leaf wetness duration on development of apple scab symptoms. For each experiment, the C3 curve (indicating heavy infection levels) was used as the basis for relating infection to temperature and leaf wetness duration. In one series of experiments, seedlings were treated with inoculum doses of 1.5, 5.4, 15.6, 32.2, 81.2, and 250 × 103 conidia/ml and leaves were kept wet during C3 infection periods at temperatures of 6, 11, 16, and 22°C. At all four temperatures, disease incidence (scab lesions/plant) increased with increasing inoculum doses up to about 81.2 × 103 conidia/ml. Disease incidence was lower at 22°C than at the other temperatures. In a second series of experiments, seedlings inoculated with 10 × 103 conidia/ml were kept moist for infection periods ranging from 0.6 to 2.0 times the C3 leaf wetness duration curve at 6, 11, 16, and 22°C. Disease incidence increased with increasing duration of leaf wetness and generally leveled off between 150 and 200% of the C3 curve. At this inoculum dose (10 × 103 conidia/ml), doubling the leaf wetness duration indicated by the C3 curve resulted in high disease incidence, similar to levels obtained with a higher inoculum (250 × 103 conidia/ml) and shorter wetness period (1.0 C3).

scholarly journals Efficient Control of Apple Scab with Targeted Spray Applications

Agronomy ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 217 ◽  
Author(s):  
Michael Chatzidimopoulos ◽  
Fenia Lioliopoulou ◽  
Thomas Sotiropoulos ◽  
Evangelos Vellios
Keyword(s):  
Venturia Inaequalis ◽  
Meteorological Data ◽  
Disease Incidence ◽  
Apple Scab ◽  
Similar Efficacy ◽  
Critical Growth ◽  
Growth Stages ◽  
Trial Site ◽  
Growing Seasons ◽  
Chemical Groups

For two consecutive growing seasons (2017 and 2018), three different fungicide spray programs, each with five sprays from unrelated chemical groups, were evaluated for their effectiveness against apple scab (causal agent: Venturia inaequalis) in an experimental trial in Greece. The targeted application programs consisted of five sprays with protective and systemic fungicides from unrelated chemical groups, in alternation. The applications were started at the pink bud stage (a copper-based fungicide had previously been applied at the green bud stage) and completed at the second fruit fall to arrest the primary infections by ascospores. These five-spray programs were compared to the standard farmer practice (12 sprays per season), whereas untreated plots were used as controls. The timing of the applications was based: a) on the critical growth stage of the crop, and b) on the risk analysis for infection calculated by the software Field Climate, which incorporated meteorological data from the trial site. All the five-spray programs were of very high efficacy against apple scab, showing disease severity ratings on leaves and fruits below 1.88%. In both years, in the untreated control, the disease incidence and severity on leaves ranged from 96.5% to 99.3% and from 65.2% to 75.93%, respectively. The five-spray programs showed similar efficacy to the standard 12-application program in all cases. From the results, it becomes apparent that apple scab can be controlled effectively by five targeted applications with selected fungicides at critical growth stages of the crop.

scholarly journals Effect of pruning on disease incidence of apple scab and powdery mildew in integrated and organic apple production

2005 ◽  
Vol 11 (1) ◽  
Author(s):  
I. J. Holb
Keyword(s):  
Powdery Mildew ◽  
Production System ◽  
Production Systems ◽  
Venturia Inaequalis ◽  
Disease Incidence ◽  
Apple Scab ◽  
Organic Production ◽  
Environmentally Benign ◽  
Apple Cultivars ◽  
Apple Production

In a three-year study, the effect of two winter pruning treatments (strong and weak) on apple scab (Venturia inaequalis) and powdery mildew (Podosphaera leucotricha) was evaluated on six apple cultivars (`Rewena', `Elstar', 'Liberty', 'Gala', 'Pilot' and `Jonica') in two environmentally-benign apple production systems (integrated and organic). Results on apple scab showed that compared to the integrated production system, the pathogen caused significantly more infection on the leaves of cvs. `Elstar', 'Gala' and `Jonica' in the organic production system. The effect of pruning treatments on apple scab was mainly detectable on the cultivars susceptible to the disease such as cvs. 'Gala' and `Jonica'. The weak pruning correlated with a higher level of apple scab infection than the strong pruning, especially in the organic production system. Primary mildew infection was very low in both protection systems (below 2 %), therefore, effect of pruning on primary mildew infection could not be analysed. Low secondary mildew incidence was detected in the organically treated orchard part; however, incidence of powdery mildew was significantly higher (P> 0.05) on cvs. 'Elstar', 'Pilot' and `Jonica' in the integrated orchard part compared to cvs. 'Gala', 'Rewena' and 'Liberty'. The highest incidence of mildew was on cv. 'Elstar'. Pruning had very low effect on incidence of secondary mildew infection on leaves.

Seasonal changes in phenolic compounds in the leaves of scab-resistant and susceptible apple cultivars

2009 ◽  
Vol 89 (4) ◽  
pp. 745-753 ◽  
Author(s):  
M Mikulic Petkovsek ◽  
F Stampar ◽  
R Veberic
Keyword(s):  
Phenolic Compounds ◽  
Seasonal Changes ◽  
High Performance ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Growing Season ◽  
Total Phenols ◽  
Apple Varieties ◽  
Apple Leaves ◽  
Apple Cultivars

Leaf samples were collected from apple varieties susceptible and resistant to apple scab [Venturia inaequalis (Cke.) Wint.] from June to September for 2 yr between 2005 and 2006. These were analyzed for phenolic compounds, using high-performance liquid chromatography (HPLC). In the apple leaves, the following hydroxycinnamic acids were detected: chlorogenic, caffeic and p-coumaric acids; the following dihydrochalcone: phloridzin, and the following flavonoids: epicatechin, catechin, rutin and quercitrin. The total of phenolic compounds in apple leaves was determined spectrophotometrically, using the Folin-Ciocalteu method. During the growing season, the content of phenolic compounds changed and was related to the physiological stage of the tissue and cultivar used. Each phenolic compound had its own curve of seasonal changes in concentration. In 2005 there was no significant change in total phenols during the growing season. In 2006, their content changed significantly during the growing season; statistically the highest content of total phenols was found in the leaves in August. Total phenols as well as single phenolics were statistically higher in resistant than in susceptible apple varieties for both years.Key words: Malus × domestica Borkh., leaves, phenolic compounds, seasonal changes, Venturia inaequalis (Cke.) Wint., resistance

scholarly journals Incorporating Adjuvants with Captan to Manage Common Apple Diseases

Plant Disease ◽  
2018 ◽  
Vol 102 (1) ◽  
pp. 231-236 ◽  
Author(s):  
Chelsi P. Abbott ◽  
Janna L. Beckerman
Keyword(s):  
Venturia Inaequalis ◽  
Disease Incidence ◽  
Apple Scab ◽  
Yield Losses ◽  
Pathogen Population ◽  
Bitter Rot ◽  
Apple Cultivars ◽  
Colletotrichum Spp ◽  
Disease Pressure ◽  
Control Failures

Captan has become an increasingly important fungicide in the management of common apple diseases such as apple scab (Venturia inaequalis) and bitter rot (Colletotrichum spp.) due to the low risk of fungicide resistance evolving in either pathogen population to this product. Restrictions on the amount of captan that can be applied per season limits the amount and the number of applications a grower may use, resulting in control failures during high disease pressure years. This 3-year field study evaluated how adjuvants combined with captan affected the incidence and severity of apple scab and bitter rot on two different apple cultivars. Results showed that Li700 plus captan and Bond Max plus captan reduced disease incidence of apple scab and bitter rot in years with moderate to high disease pressure by increasing the coverage and retention of captan. The addition of these adjuvants also resulted in possible yield losses due to russetting caused by phytotoxicity. The overall benefits of incorporating adjuvants with captan based on this study could reduce disease incidence while potentially saving a grower up to $5,329 ha–1 due to fungicide reduction.

scholarly journals Genetic diversity of Venturia inaequalis isolates (Apple scab) in China and U.K. determined by SSR markers

PLoS ONE ◽  
2021 ◽  
Vol 16 (6) ◽  
pp. e0252865
Author(s):  
Xiancheng Li ◽  
Fei Tao ◽  
Sanhong Fan ◽  
Haiyuan Li ◽  
Jiarong Yang ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Venturia Inaequalis ◽  
Management Strategies ◽  
Apple Scab ◽  
Genetic Distances ◽  
Group Iv ◽  
Group V ◽  
Group I ◽  
Group Ii ◽  
High Level

Apple scab caused by Venturia inaequalis is a serious disease of cultivated apple worldwide. In this study, we collected 132 V. inaequalis isolates from Shaanxi, Gansu, Xinjiang, and the U.K. and analyzed their genetic diversity by using 13 microsatellite markers. Cluster analysis based on population structure and genetic distances suggested high similarity among the four regions. Population differentiation values ranged from 0.044 to 0.155, indicating there is a high level of kinship among the four regions. All isolates could be divided into 5 lineages with a 0.76 similarity coefficient. Among the four regions, Shaanxi had only one lineage, Group II; Gansu had four lineages, Group I, Group II, Group IV, and Group V; Xinjiang had all five lineages, Group I, Group II, Group III, Group IV, and Group V; and the U.K. had three lineages, Group I, Group II and Group IV. High molecular variance was detected for populations in the four regions, with 91% of the variance occurring within the populations and 9% among the populations. Structure analysis there are three common ancestors of these four regions. The results of the present study shed light on the genetic diversity of V. inaequalis in Shaanxi, Gansu and Xinjiang, which will lead to the development of more effective management strategies and new resistant apple cultivars through molecular marker-assisted selection.

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