Common Scab Research Articles

Biocontrol of Potato Common Scab Cultivated on Different Soil Mulch

Potato common scab causes significant economic losses worldwide, and current control methods remain ineffective. However, biological control methods have been effective in controlling phytopathogens in several other crops. Trichoderma spp. and Bacillus subtilis are the most studied microorganisms in agriculture for controlling plant diseases. However, interactions between these biological control agents and the organic matter present at the cultivation site have not been extensively studied. Therefore, the objective of this study was to evaluate the action of biological agents in controlling potato common scab using different soil mulch compositions. Two field experiments were performed simultaneously: one tested T. longibrachiatum (TL) and T. asperellum (TA) treatments in the control of potato scab, and the other tested two types of soil mulch (vetch and palisade grass) and four microorganism treatments (TL, TA, B. subtilis + Enterococcus faecium + Lactobacillus plantarum (BSEFLP), and B. subtilis + B. licheniformis + T. longibrachiatum (BSBLTL)). In the first experiment, TL and TA decreased the disease severity from 80% in the control to 34%, and 56% in the control to 5%, respectively, based on yield losses caused by the potato scab. In the second experiment, TA and BSEFLP reduced the disease severity to 61% and 62%, respectively, compared with that in the control (98%), and losses caused by the common scab to 38% and 40%, respectively, when combined with vetch mulch (control: 98%), demonstrating that microbial response can be influenced by the cover crop. Therefore, this work provides evidence that biological control of potato common scab is a viable alternative for disease control.

In vitro and in vivo efficacy of some chemicals against common scab (Streptomyces scabies) of potato

Bactericides Krosin AG and Timsen; fungicides Oxicob, Micra 72WP, Provex 200WP, and Amister Top; and plant nutrients Mag Plus and Alpha Boron Plus were evaluated against Streptomyces scabies in vitro and under field conditions. Among the chemicals, Oxicob (3500 ppm) and Krosin AG (2000 ppm) demonstrated maximum zone of inhibition against S. scabies by 20.61 and 19.74 mm, respectively in in vitro. In field, maximum reduction of common scab incidence by number (64.99%) & weight (66.02%), and severity (73.53%) was achieved by Oxicob. Along with the reduction of common scab incidence by number (49.92%) & weight (47.70%), and severity (49.47%), Alpha Boron Plus resulted the highest potato tuber yield (18.07 ton ha−1) in comparison to other chemicals. The present study suggests that combination of Oxicob and Alpha Boron Plus can be applied in the field to increase potato tuber yield.

Health status of carrots Daucus carota L. ssp. sativus grown in integrated and organic farming systems

Carrot culrivars ‘Bolero’, ‘Fayette F1’, ‘Flakke, Koral’, ‘Nantes’, ‘Perfekcja’ and ‘Sukces’ were grown in integrated and organic farming systems. The severity of Alternaria leaf blight and root diseases was evaluated at harvest and after five months of storage. Fungi were isolated from carrot roots. Disease severity was affected by the years of the study, farming system and cultivar. The severity of Alternaria leaf blight was lower in the integrated farming system than in the organic system. Carrots of cvs. ‘Bolero’ and ‘Fayette F1’ were healthiest. In both production systems, the symptoms of mixed rot (soft rot, Pectobacterium carotovorum subsp. carotovorum and Sclerotinia rot, Sclerotinia sclerotiorum), dry rot (Fusarium spp.), common scab (Streptomyces scabies), crater rot (Rhizoctonia carotae) and black rot (Alternaria radicina, A. dauci) were encountered sporadically, and their severity was low on carrot roots analyzed at harvest. Disease symptoms became more severe during storage, and they were more frequently observed on carrot roots in the organic farming system. Cultivars exerted varied effects on the severity of the analyzed root diseases. The fungal pathogens isolated from carrot roots confirmed the presence of disease symptoms.

Antimicrobial effect and mechanism of bovine lactoferrin against the potato common scab pathogen Streptomyces scabiei

Lactoferrin (LF) is a multifunctional protein with a broad spectrum of antimicrobial activities. In this study, we investigated the antimicrobial activity of LF against the potato common scab pathogen Streptomyces scabiei, which causes severe damage to potato tubers. LF derived from bovine (bLF) had much higher activity against S. scabiei than human LF. The minimal inhibitory concentration of bLF was 3.9 μM. The effects of both apo-bLF (iron-free) and holo-bLF (iron-saturated) on S. scabiei were not different. Bovine lactoferricin (LFcinB), a short peptide with a length of 25 amino acid residues located in the N-terminal region of bLF, showed antimicrobial activity against S. scabiei, similar to that of bLF. These results indicated that the antimicrobial activity of bLF against S. scabiei cannot be attributed to its iron-chelating effect but to the bioactivity of its peptides. When S. scabiei was treated with the fusion protein of mCherry-LFcinB (red fluorescent protein) expressed in Escherichia coli, the pseudohyphal cells instantly glowed, indicating that the peptide electrostatically binds to the surface of S. scabiei. An assay of synthetic peptides, with modified number of arginine (Arg) and tryptophan (Trp) residues based on the antimicrobial center (RRWQWR) of LFcinB showed that Trp residues are implicated in the antimicrobial activity against S. scabiei; however, Arg residues are also necessary to carry Trp residues to the cell surface to fully exert its activity. Although the single amino acid effect of Trp had low activity, Trp derivatives showed much higher activity against S. scabiei, suggesting that the derivatives effectively bind to the cell surface (cell membrane) by themselves without a carrier. Thus, amino acid derivatives might be considered effective and alternative antimicrobial substances.

Results of studying promising breeding potato hybrids under irrigated conditions in the Orenburg region

The main focus of the work on breeding hybrids is the evaluation and selection of breeding material for the desired traits under the conditions of the specific cultivation zone. Obtaining new promising potato varieties is an important task that breeders face. Currently, import substitution is the main tool in solving the problem of food security in the country. Agricultural scientists understand import substitution as increasing the output of domestic products while reducing the import of imported goods, especially in times of economic crisis. Import substitution aims to increase national goods’ competitiveness and export potential in the world food market. The purpose of this study is to study and select the most promising and adapted to the conditions of the Orenburg region potato hybrids from the breeding material of FSBSI (Federal State Budgetary Scientific Institution) “South Ural Research Institute (Research Institute) of Horticulture and Potato Production”. The research was conducted by the Methodology of Potato Crop Research (1967), International Classifier of CMEA (Council for Mutual Economic Assistance) (1984), Methodological Recommendations on the Methodology of Breeding Processes for Potato Crop (1980). The authors studied the potential of yield formation and infestation by the main common pathogens in potato breeding hybrids were carried out on the irrigated plot of K(F)X (peasant farm) “Khomutsky V.I.”. Perevolotsk district of Orenburg region in the period from 2019 to 2021. For the experimental plot, the soil cover was southern medium-humus medium-poddy chernozem. Of the 19 hybrids studied, only 21 % produced yields higher than those of the standard variety in the 3-year trials. The remaining hybrids, 79 %, show much lower yields. During the same period, 26 % of the hybrids studied were affected by common pathogens. The maximum damage of potato tubers by table rot was found in breeding hybrids 13.20.101 (5.1 %), 13.10.11 (4.5 %) and M 14.16.25 (3.3 %), common scab - 13.32.1 (26.5 %), M 14.18.99 (18.3 %) and 13.20.9 (17 %). As a result, the authors identified promising potato breeding material for further work. This hybrid is Olninsk13.30.2 (38.1 t/ha), 10.76.1 (60.9 t/ha), M 14.07.08 (38.1 t/ha), M 14.07.6 (51.1 t/ha). It combines low pathogen infestation and higher yields compared to other hybrids.

Streptomyces caniscabiei sp. nov., which causes potato common scab and is distributed across the world.

Fourteen strains of Streptomyces isolated from scab lesions on potato are described as members of a novel species based on genetic distance, morphological observation and biochemical analyses. Morphological and biochemical characteristics of these strains are distinct from other described phytopathogenic species. Strain NE06-02DT has white aerial mycelium and grey, cylindrical, smooth spores on rectus-flexibilis spore chains. Members of this species group can utilize most of the International Streptomyces Project sugars, utilize melibiose and trehalose, produce melanin, grow on 6-7 % NaCl and pH 5-5.5 media, and are susceptible to oleandomycin (100 µg ml-1), streptomycin (20 µg ml-1) and penicillin G (30 µg ml-1). Though the 16S rRNA gene sequences from several members of this novel species are identical to the Streptomyces bottropensis 16S rRNA gene sequence, whole-genome average nucleotide identity and multi-locus sequence analysis confirm that the strains are members of a novel species. Strains belonging to this novel species have been isolated from the United States, Egypt and China with the earliest known members being isolated in 1961 from common scab lesions of potato in both California, USA, and Maine, USA. The name Streptomyces caniscabiei sp. nov. is proposed for strain NE06-02DT (=DSM111602T=ATCC TSD-236T) and the other members of this novel species group.

Plant Natural Products as Antimicrobials for Control of Streptomyces scabies: A Causative Agent of the Common Scab Disease.

The common scab disease caused by Streptomyces scabies, a soil-dwelling Gram-positive bacterium, is an economically important disease of potatoes and other tuber crops. The lack of effective treatments against this disease accounts for large economic losses globally. Plant extracts were screened to find several that effectively inhibited Streptomyces scabies growth in culture. Seven tinctures showed the greatest inhibition of S. scabies growth by reducing pathogen growth in culture by 75% or more. These extracts were myrrh, garlic, cayenne, barberry, frankincense, wild indigo root, and lavender. Myrrh extract from Commiphora myrrha, a resin made from tree sap, showed strong antibacterial activity by reducing the growth of S. scabies to 13% of the control. Additionally, a flavonoid library was screened to identify several compounds that were effective to control the pathogen growth. The flavonoids that showed the greatest inhibition of Streptomyces scabies growth were sophoraflavanone G, jaceosidin, baicalein, and quercetin. Minimum inhibitory concentrations for the effective flavonoids were calculated to be 6.8 ± 0.4 μM, 100.0 ± 2.1 μM, 202.9 ± 5.3 μM, and 285.2 ± 6.8 μM, respectively. The mean lethal doses for these flavonoids against Streptomyces scabies were 2.0 ± 0.1 μM, 22.6 ± 0.5 μM, 52.9 ± 1.3 μM, and 37.8 ± 1.0 μM, respectively. A live/dead assay showed complete cell death in the presence of sophoraflavanone G indicative of a bactericidal mechanism for flavonoid action on Streptomyces scabies. Scanning electron and transmission electron microscopy imaging showed damaged cell membrane morphologies when Streptomyces scabies was exposed to these flavonoids. Mycelia appeared as flat and deflated structures with contents seen as spewing from branching hyphae with numerous holes and tears in the membrane structure indicative of cell death. Sophoraflavanone G showed the greatest potency and potential as a natural antibiotic from the library of tested flavonoids. These results suggest that these plant compounds act on the pathogen through a bactericidal mechanism involving cell membrane destabilization and disruption leading to cell death.

Foliar Application of Fungicides Registered Against Late Blight Influences Main Potato Tuber Diseases and Key Quantitative Characteristics of Tubers

Adequate integrated management of potato leaf diseases can have an influence on pathogens which are challenging to control and cause main potato tuber diseases. Deriving from this hypothesis, an experiment was designed to evaluate the efficacy of foliar application of twelve fungicides on late blight in tubers, common scab, black scurf and silver scurf. In the period of 2013 to 2017, the fungicides were equally applied six times in registered doses during the growing seasons. Eight tuber disease indicators and eight yield characteristics were then evaluated in harvested tuber samples. Significant differences were found among the fungicides used. In comparison to the negative control (n. c.), the application of Infinito, Ranman Top and Revus Top reduced the quantity of tubers infected by late blight by 72% on average. The incidence of common scab increased by 65% of n. c. under the effect of copper oxychloride, while an average reduction by 19% of n. c. was observed with the use of Acrobat MZ WG, Curzate Gold and Consento. The occurrence of silver scurf was significantly enhanced by Curzate Gold and Consento (105% of n. c.), while it was suppressed by Revus Top and Revus (85% of n. c.). All fungicides were ineffective on black scurf yet had a positive influence on the potato yield and quality, with the choice of fungicide having a great impact on the quality of tubers. The application of any safe fungicide is important, especially in years similar to 2015, which was the most devastating recent year for potato production in terms of structural changes in yield of tubers.

First Report of Streptomyces stelliscabiei Causing Potato Common Scab in Guizhou Province, China.

Potato (Solanum tuberosum L.) common scab can be caused by multiple pathogenic Streptomyces spp. worldwide. Potato tubers (cv. Favorita) with severe pitted common scab symptoms were observed at a small farm (2 hectares) during harvest in Anshun, Guizhou province in early May 2020. The disease incidence was around 10%, and symptomatic samples were collected to isolate the pathogen. Two isolates, ZR-IMU141 and ZR-IMU146 (Accession number MW995958 and MW995959 respectively), showed more than 99% sequence identity to S. stelliscabiei sequences (Accession No. HM018085). Five house-keeping genes for multi-locus sequence analyze (MLSA) of Streptomycetaceae were amplified, sequenced and uploaded to NCBI: atpD (MZ343164 and MZ343165), gyrB (MZ343162 and MZ343163), recA (MZ343166 and MZ343167), rpoB (MZ343168and MZ343169) and trpB (MZ343170 and MZ343171). All the genes show over 98% identity with S. stelliscabiei. Phylogenetic trees of 16S rRNA gene sequence and multi-locus sequence analysis (MLSA) were constructed. The two isolates contain pathogenicity genes txtAB, nec1, and tomA, which was confirmed by PCR. To complete Koch's postulates, 9 potato seedlings (cv. Favorita, 15 centimeters high), were transferred to new pots and inoculated with spore suspensions of ZR-IMU141 and ZR-IMU146 (104 CFU/ml), or water as a negative control. Two months later, potato tubers inoculated with either ZR-IMU141 or ZR-IMU146 exhibited typical symptoms of potato common scab, such as superficial or deep, raised, pitted, or polygonal lesions like the field symptoms, but the negative controls remained asymptomatic. The pathogens were reisolated from the lesions and confirmed identical to the original isolate by 16s rRNA gene sequences. To our knowledge, this is the first report of S. stelliscabiei causing potato common scab in Guizhou province, China. We believe that this report will draw attention to the study and management of the increased pool of scab pathogens in China.

Streptomyces rhizophilus Causes Potato Common Scab Disease.

Common scab (CS) caused by Streptomyces spp. is a significant soilborne potato disease that results in tremendous economic losses globally. Identification of CS-associated species of the genus Streptomyces can enhance understanding of the genetic variation of these bacterial species and is necessary for the control of this epidemic disease. The present study isolated Streptomyces strain 6-2-1(1) from scabby potatoes in Keshan County, Heilongjiang Province, China. PCR analysis confirmed that the strain harbored the characteristic Streptomyces pathogenicity island (PAI) genes (txtA, txtAB, nec1, and tomA). Pathogenicity assays proved that the strain caused typical scab lesions on potato tuber surfaces and necrosis on radish seedlings and potato slices. Subsequently, the strain was systemically characterized at morphological, physiological, biochemical, and phylogenetic levels. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain 6-2-1(1) shared 99.86% sequence similarity with Streptomyces rhizophilus JR-41T, isolated initially from bamboo in rhizospheric soil in Korea. PCR amplification followed by Sanger sequencing of the 16S rRNA gene of 164 scabby potato samples collected in Heilongjiang Province from 2019 to 2020 demonstrated that approximately 2% of the tested samples were infected with S. rhizophilus. Taken together, these results demonstrate that S. rhizophilus is capable of causing potato CS disease and may pose a potential challenge to potato production in Heilongjiang Province of China.

Early prediction of potato tuber diseases using ann classifier

Many plant diseases have distinct visual symptoms, which can be used to identify and classify them correctly. This article presents a potato tuber disease classification algorithm that leverages these distinct appearances and advances in computer vision made possible by machine learning. It is estimated that the major loss occurred in potato yield due to the diseases. In present study, we have collected sample of potato tuberdisease images from crop field and valid dataset. This dataset contains 210 images of potato tuber disease. It has 3 class of sample of Black Scurf, Common Scab and Green Colour. The 76 features are extracted from these images regarding color, texture and area. The extracted features are used to develop a model. The developed model is based on neural network for prediction and classification of potato image samples. The Feed Forward Neural Network (FFNN) Model is used for prediction and classification of unknown tuber disease. The average accuracy of ANN model is achieved 84.60%. Classifier is helpful in early and accurate prediction of the tuber diseases of potato crop.

‘BRS F183’ (Potira): Cultivar de batata de duplo propósito, com alto potencial produtivo e excelente qualidade de fritura de palitos

ABSTRACT ‘BRS F183’ (Potira) is a late-maturing and red skin potato cultivar, suitable for French fry processing, due to tuber high dry matter content of long oval shape, large size, light yellow flesh, and light fry color. It is also suitable for the fresh market due to its attractive tubers of intense red color, smooth skin and shallow eyes. In six trials, ‘BRS F183’ showed average tuber yields that did not differ from ‘Asterix’. The marketable yield was relatively high, reaching 98.5% in the tropical ecosystem. Larger tubers of ‘BRS F183’ than ‘Asterix’ were also observed in the autumn crop of the subtropical ecosystem. In most of the trials, the dry matter content was higher than that of ‘Asterix’, varying from 20.5 to 23.0%. A very low incidence of tuber disorders was observed in ‘BRS F183’, with the secondary growth lower than ‘Asterix’. ‘BRS F183’ presented medium tuber dormancy. Tuber glucose content suitable for French fry processing (≤1.2 mg g-1 of fresh mass) was shown by ‘BRS F183’ after harvest and storage at 7.5°C, 8.9°C and 20°C for up to 180 days, while ‘Asterix’ was suitable up to 120 days after storage at 8.9ºC. ‘BRS F183’ is moderately resistant to early blight and moderately susceptible to late blight. It is susceptible to PVY, PLRV, and root-knot nematode. Field observations indicate that resistance/susceptibility to soft rot, black scurf, and bacterial wilt of ‘BRS F183’ is not different from the main cultivars grown in the country. However, higher susceptibility to common scab was shown in some validation tests. ‘BRS F183’ was released in 2020 by Embrapa, as a product of the breeding program developed by Embrapa Temperate Agriculture and Embrapa Vegetables.

Agroeconomic efficiency of chemical ameliorants new forms for potato cultivation

Applying granulated AgroMag to the soil in doses of 100-200 kg/ha annually and foliar treatment with AgroMag AktiMax during the growing season in combination with NPK-fertilizers with a predominance of potassium (N:P:K = 1:1-1.3:1.3-1.5) provides a significant increase in potato yields, a decrease in tuber morbidity common scab, improving the quality of products and increasing the fertility of acidic sod-podzolic soils.

A Perspective on Common Scab (Streptomyces scabiei) Disease Management Strategies in Potato Crop

Potato common scab (CS), caused by Streptomyces scabiei, and is a major potato disease that causes deep pitted lesions on the surface of the tuber. The market value and quality of tubers with CS are reduced, resulting in significant economic losses to potato growers. Traditional control strategies such as irrigation and reduced soil pH help to reduce CS but are not efficient methods. Celest® 100 FS (Fludioxanil), Emesto® 24% FS (Penflufen) and Bio magic® (Bacillus subtilis) were tested on CS in this study. A disc diffusion method was used to evaluate the efficacy of these products under in vitro conditions at three different concentrations: 100 ppm, 200 ppm, and 300 ppm. After 7 days, results showed that Bio Magic was the most effective at reducing the growth of Streptomyces scabiei, followed by Emesto 24 FS and Celest 100 FS at 300 ppm. The maximum inhibition percentage by Bio Magic was 45.05%, followed by Celest 100FS at 38.38% and Emesto 24FS at 31.47%. In greenhouse experiments, Celest 100FS treated potato tubers produced the highest yield of 2250g per pot (10" x 10" inch), followed by Bio Magic at 2000g, Emesto 24FS at 1850g, and the non-treated control at 1300g.The data indicated that Celest 100FS provided the best control of CS in greenhouse trials.

Efficacy of Some Biocontrol Agents Against Streptomyces scabiei the Causative of Common Scab Disease in Potatoes

Efficacy of Some Biocontrol Agents Against Streptomyces scabiei the Causative of Common Scab Disease in Potatoes

Old Enzyme, New Role: The β-Glucosidase BglC of Streptomyces scabiei Interferes with the Plant Defense Mechanism by Hydrolyzing Scopolin

The beta-glucosidase BglC fulfills multiple functions in both primary metabolism and induction of pathogenicity of Streptomyces scabiei, the causative agent of common scab in root and tuber crops. Indeed, this enzyme hydrolyzes cellobiose and cellotriose to feed glycolysis with glucose directly and modifies the intracellular concentration of these cello-oligosaccharides, which are the virulence elicitors. The inactivation of bglC led to unexpected phenotypes such as the constitutive overproduction of thaxtomin A, the main virulence determinant of S. scabiei. In this work, we reveal a new target substrate of BglC, the phytoalexin scopolin. Removal of the glucose moiety of scopolin generates scopoletin, a potent inhibitor of thaxtomin A production. The hydrolysis of scopolin by BglC displayed substrate inhibition kinetics, which contrasts with the typical Michaelis–Menten saturation curve previously observed for the degradation of its natural substrate cellobiose. Our work, therefore, reveals that BglC targets both cello-oligosaccharide elicitors emanating from the hosts of S. scabiei, and the scopolin phytoalexin generated by the host defense mechanisms, thereby occupying a key position to fine-tune the production of the main virulence determinant thaxtomin A.

Bacterial Community Is Affected by Locations and Time Rather Than Potato Varieties but Streptomyces spp. Are Related to Potato Varieties

Improved knowledge and a better understanding of the functions of bacterial communities are vital for effective crop disease management. This study was conducted to study a bacterial community’s relationship with the common scab in four different potato varieties (Dejima, DJ; Atlantic, DS; Seohong, SH; Haryeong, HY) at two different locations (Gangneung and Chuncheon) and spatial locations (rhizosphere and furrow) at two different times (preharvest and postharvest). In addition, metagenomic sequencing was performed by extracting genomic DNA from soil samples to observe the dominant bacterial microbes and disease severity of the common scab in all the tested varieties in spatial location and time. The results suggest that the most dominant bacterial phyla in all the soil samples were Proteobacteria, Acidobacteria, and Bacteroidetes. Additionally, Streptomyces spp. were found to be more abundant in the susceptible variety (DJ) than in other varieties (DS, SH, and HY). Interestingly, bacterial communities were found to be more diverse across the two different geographical locations, spatial locations, and harvesting times, rather than the variety of potato, according to PCoA analysis. There were no interlinked changes in bacterial communities among the varieties. Moreover, the 14 most dominant bacterial genus correlation networks with Streptomyces spp. suggested that there was a significant positive and negative correlation to some extent. Alpha and beta diversity results clearly indicated that the possible reason for differences in bacterial communities might have been due to the different spatial locations, in comparison with varieties, which suggests that there was no significant correlation between bacterial community richness and diversity among the varieties.

ITRAQ-Based Proteomics Analysis of Response to Solanum tuberosum Leaves Treated with the Plant Phytotoxin Thaxtomin A.

Thaxtomin A (TA) is a phytotoxin secreted by Streptomyces scabies that causes common scab in potatoes. However, the mechanism of potato proteomic changes in response to TA is barely known. In this study, the proteomic changes in potato leaves treated with TA were determined using the Isobaric Tags for Relative and Absolute Quantitation (iTRAQ) technique. A total of 693 proteins were considered as differentially expressed proteins (DEPs) following a comparison of leaves treated with TA and sterile water (as a control). Among the identified DEPs, 460 and 233 were upregulated and downregulated, respectively. Based on Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses, many DEPs were found to be involved in defense and stress responses. Most DEPs were grouped in carbohydrate metabolism, amino acid metabolism, energy metabolism, and secondary metabolism including oxidation–reduction process, response to stress, plant–pathogen interaction, and plant hormone signal transduction. In this study, we analyzed the changes in proteins to elucidate the mechanism of potato response to TA, and we provided a molecular basis to further study the interaction between plant and TA. These results also offer the option for potato breeding through analysis of the resistant common scab.

The effect of nanoparticles of metals and nonmetals of multicomponent trace element preparation «Avatar-2 protection» and microbial preparation «Azogran» on the incedence and severity of infectious diseases of potato

The aim of the research was to study the influence of nanoparticles (NPs) of metals and nonmetals of multicomponent trace element preparation «Avatar-2 protection» and microbial preparation «Azogran» on infectious diseases of potato in vivo. Affection of potato cultivar Suvenir Chernihivskyi by diseases was evaluated in two small plot studies on soddy podzolic soil and alkaline chernozem. Symptoms of common scab and dry rot in tubers were identified visually and then the severity and the rate of the diseases were calculated. The presence of viruses in plants was examined by agglutination tests and the rates of the viral infections were calculated. The results of the study indicate that on the soddy podzolic soil the composition of Se+I NPs significantly decrease disease severity of both common scab and dry rot by 20.00 and 17.50% respectively, whereas «Avatar-2 protection» preparation, «Azogran» preparation and the combination of «Azogran» preparation with the composition of Se+I NPs significantly decreased only the severity of dry rot by 22.50%. The combination of «Azogran» preparation with the composition of Se+I NPs significantly decreased the incidence and the disease severity of common scab, the incidence and the disease severity of dry rot on the alkaline chernozem by 40.00; 30.00; 25.00 and 30.00% respectively; whereas «Avatar-2 protection» preparation significantly decreased the incidence of viral diseases by 33.33–66.67% on both soils. The effect of the composition of Se+I NPs, «Avatar-2 protection» preparation and «Azogran» preparation is promising for further investigation. Particularly, an abundance of different groups of microorganisms in potato’s rhizosphere under the treatment with studied substances needs to be evaluated in order to understand the mechanisms diseases’ incidence and severity decrease. The effect of the studied NPs and preparations on other diseases of potato and diseases of other agricultural crops needs to be studied. The results of these studies can be useful for the development of the control methods for various infectious diseases of agricultural crops.

Quantitative Trait Locus Mapping for Common Scab Resistance in a Tetraploid Potato Full-Sib Population.

Despite the negative impact of common scab (Streptomyces spp.) on the potato industry, little is known about the genetic architecture of resistance to this bacterial disease in the crop. We evaluated a mapping population (∼150 full sibs) derived from a cross between two tetraploid potatoes ('Atlantic' × B1829-5) in three environments (MN11, PA11, ME12) under natural common scab pressure. Three measures to common scab reaction, namely percentage of scabby tubers and disease area and lesion indices, were found to be highly correlated (>0.76). Because of the large environmental effect, heritability values were zero for all three traits in MN11, but moderate to high in PA11 and ME12 (∼0.44 to 0.79). We identified a single quantitative trait locus (QTL) for lesion index in PA11, ME12, and joint analyses on linkage group 3, explaining ∼22 to 30% of the total variation. The identification of QTL haplotypes and candidate genes contributing to disease resistance can support genomics-assisted breeding approaches in the crop.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.