Search Results (13)

Potato common scab is one of the major diseases posing a threat to potato production on a global scale. No chemical agents have been found to effectively control the occurrence of this disease, and research on the identification of resistance genes and the development of molecular markers remains relatively limited. In this study, a diploid potato variety H535, which exhibits resistance to the predominant pathogen Streptomyces scabies, was utilized as the male parent, whereas the susceptible diploid potato variety H012 served as the female parent. Building upon the resistance QTL intervals pinpointed through a genome-wide association study, two potential resistance loci were localized on chromosome 2 of the potato genome, spanning the regions between 38–38.6 Mb and 41.3–42.7 Mb. These intervals accounted for 18.03% of the total phenotypic variance and are presumed to be the primary QTLs underlying scab resistance. Building upon this foundation, we expanded the hybrid progeny population, conducted resistance assessments, selected individuals with extreme phenotypes, developed molecular markers, and conducted fine mapping of the resistance gene. A phenotypic evaluation of scab resistance was carried out using a pot-based inoculation test on 175 potato hybrid progenies to characterize the F1 generation population. Twenty lines exhibiting high resistance and thirty lines displaying high susceptibility were selected for investigations. Within the preliminary mapping interval on potato chromosome 2 (spanning 38–43 Mb), a total of 214 SSR (Simple Sequence Repeat) and 133 InDel (Insertion/Deletion) primer pairs were designed. Initial screening with parental lines identified 18 polymorphic markers (8 SSR and 10 InDel) that demonstrated stable segregation patterns. Validation using bulked segregant analysis revealed that 3 SSR markers (with 70–90% linkage) and 6 InDel markers (with 70–90% linkage) exhibited significant co-segregation with the resistance trait. A high-density genetic linkage map spanning 104.59 cm was constructed using 18 polymorphic markers, with an average marker spacing of 5.81 cm. Through linkage analysis, the resistance locus was precisely mapped to a 767 kb interval (41.33–42.09 Mb) on potato chromosome 2, flanked by SSR-2-9 and InDel-3-9. Within this refined interval, four candidate disease resistance genes were identified: RHC02H2G2507, RHC02H2G2515, PGSC0003DMG400030643, and PGSC0003DMG400030661. This study offers novel insights into the genetic architecture underlying scab resistance in potato. The high-resolution mapping results and characterized markers will facilitate marker-assisted selection (MAS) in disease resistance breeding programs, providing an efficient strategy for developing cultivars with enhanced resistance to Streptomyces scabies. Full article

Potato (Solanum tuberosum L.) is a major staple crop globally, yet its production is severely impacted by common scab, a disease caused by Streptomyces spp., leading to substantial economic losses. This study evaluated copper sulfate (CuSO₄) and zinc sulfate (ZnSO₄) as potential control agents for common scab, focusing on their antimicrobial properties and effects on potato resistance mechanisms. Both CuSO₄ and ZnSO₄ exhibited dose-dependent inhibition of Streptomyces spp., significantly reducing the production of the pathogenic toxin Thaxtomin A by 57.02% and 41.29%, respectively. Electrical conductivity assays indicated their disruptive effects on cell membrane integrity, and HPLC confirmed their suppression of toxin production. Pot experiments showed that these treatments enhanced plant growth, chlorophyll content, and defense enzyme activities (SOD, POD, CAT, PPO), while reducing malondialdehyde (MDA) levels. qPCR analysis revealed upregulation of defense-related genes (PR1, PR3, PR9, SOD1, HSF1). Field trials demonstrated disease control efficiencies of 56.58% and 59.06% for CuSO₄ and ZnSO₄, respectively, with ZnSO₄ increasing yield by 19.29%. These findings highlight CuSO₄ and ZnSO₄ as effective agents for suppressing Streptomyces spp. and enhancing potato resistance, offering practical value for sustainable potato production systems. Full article

This study investigates the early detection of sweet potato scab by using hyperspectral imaging and machine learning techniques. The research focuses on developing an accurate, economical, and non-destructive approach for disease detection and grading. Hyperspectral imaging experiments were conducted on two sweet potato varieties: Guangshu 87 (resistant) and Guicaishu 2 (susceptible). Data preprocessing included denoising, region of interest (ROI) selection, and average spectrum extraction, followed by dimensionality reduction using principal component analysis (PCA) and random forest (RF) feature selection. A novel dynamic grading method based on spectral-time data was introduced to classify the early stages of the disease, including the early latent and early mild periods. This method identified significant temporal spectral changes, enabling a refined disease staging framework. Key wavebands associated with sweet potato scab were identified in the near-infrared range, including 801.8 nm, 769.8 nm, 898.5 nm, 796.4 nm, and 780.5 nm. Classification models, including K-nearest neighbor (KNN), support vector machine (SVM), and linear discriminant analysis (LDA), were constructed to evaluate the effectiveness of spectral features. Among these classification models, the MSC-PCA-SVM model demonstrated the best performance. Specifically, the Susceptible Variety Disease Classification Model achieved an overall accuracy (OA) of 98.65%, while the Combined Variety Disease Classification Model reached an OA of 95.38%. The results highlight the potential of hyperspectral imaging for early disease detection, particularly for non-destructive monitoring of resistant and susceptible sweet potato varieties. This study provides a practical method for early disease classification of sweet potato scab, and future research could focus on real-time disease monitoring to enhance sweet potato crop management. Full article

Potato common scab (CS) caused by Streptomyces scabiei is a severe disease that threatens tuber quality and its market value. To date, little is known about the mechanism regulating the resistance of potato to CS. In this study, we identified a presequence translocase-associated motor 16 gene from potato (designated StPAM16-1) that is involved in the response to the phytotoxin thaxtomin A (TA) secreted by S. scabiei. The StPAM16-1 protein was localized in the mitochondria, and the expression of the gene was upregulated in potato leaves treated with TA. The suppression of StPAM16-1 in potato led to enhanced resistance to TA and S. scabiei. Protein interaction analyses revealed that StPAM16-1 interacted with the subunit 5b of the COP9 signalosome complex (StCSN5). Similar to that of StPAM16-1, the expression levels of StCSN5 significantly increased in potato leaves treated with TA. These results indicated that StPAM16-1 acted as a negative regulator and was functionally associated with StCSN5 in the immune response of potato plants against CS. Our study sheds light on the molecular mechanism by which PAM16 participates in the plant immune response. Furthermore, both StPAM16-1 and StCSN5 could be potential target genes in the molecular breeding of potato cultivars with increased resistance to CS. Full article

Most cultivated potato (Solanum tuberosum) varieties are highly susceptible to common scab (Streptomyces scabei). The disease is widespread in all major potato production areas and leads to high economic losses and food waste. Varietal resistance is seen as the most viable and sustainable long-term management strategy. However, resistant potato varieties are scarce, and their genetic architecture and resistance mechanisms are poorly understood. Moreover, diploid potato relatives to commercial potatoes remain to be fully explored. In the current study, a panel of 384 ethyl methane sulfonate (EMS)-mutagenized diploid potato clones were evaluated for common scab coverage, severity, and incidence traits under field conditions, and genome-wide association studies (GWASs) were conducted to dissect the genetic architecture of their traits. Using the GAPIT-MLM and RTM-GWAS statistical models, and Mann–Whitney non-parametric U-tests, we show that 58 QTNs/QTLs distributed on all 12 potato chromosomes were associated with common scab resistance, 52 of which had significant allelic effects on the three traits. In total, 38 of the 52 favorable QTNs/QTLs were found to be pleiotropic on at least two of the traits, while 14 were unique to a single trait and were found distributed over 3 chromosomes. The identified QTNs/QTLs showed low to high effects, highlighting the quantitative and multigenic inheritance of common scab resistance. The QTLs/QTNs associated with the three common scab traits were found to be co-located in genomic regions carrying 79 candidate genes playing roles in plant defense, cell wall component biosynthesis and modification, plant–pathogen interactions, and hormone signaling. A total of 61 potato clones were found to be tolerant or resistant to common scab. Taken together, the data show that the studied germplasm panel, the identified QTNs/QTLs, and the candidate genes are prime genetic resources for breeders and biologists in breeding and targeted gene editing. Full article

Modern potato varieties from high-input, conventional farming-focused breeding programs produce substantially (up to 45%) lower yields when grown in organic production systems, and this was shown to be primarily due to less efficient fertilization and late blight (Phytophthora infestans) control methods being used in organic farming. It has been hypothesized that the breeding of potato varieties suitable for the organic/low-input sector should (i) focus on increasing nutrient (especially N) use efficiency, (ii) introduce durable late blight resistance, and (iii) be based on selection under low-input conditions. To test this hypothesis, we used an existing long-term factorial field experiment (the NEFG trials) to assess the effect of crop management practices (rotation design, fertilization regime, and crop protection methods) used in conventional and organic farming systems on crop health, tuber yield, and mineral composition parameters in two potato varieties, Santé and Sarpo mira, that were developed in breeding programs for high and low-input farming systems, respectively. Results showed that, compared to Santé, the variety Sarpo mira was more resistant to foliar and tuber blight but more susceptible to potato scab (Streptomyces scabies) and produced higher yields and tubers with higher concentrations of nutritionally desirable mineral nutrients but lower concentrations of Cd. The study also found that, compared to the Cu-fungicides permitted for late blight control in organic production, application of synthetic chemical fungicides permitted and widely used in conventional production resulted in significantly lower late blight severity in Sante but not in Sarpo mira. Results from both ANOVA and redundancy analysis (RDA) indicate that the effects of climatic (precipitation, radiation, and temperature) and agronomic (fertilization and crop protection) explanatory variables on crop health and yield differed considerably between the two varieties. Specifically, the RDA identified crop protection as a significant driver for Santé but not Sarpo mira, while precipitation was the strongest driver for crop health and yield for Sarpo mira but not Santé. In contrast, the effect of climatic and agronomic drivers on tuber mineral and toxic metal concentrations in the two varieties was found to be similar. Our results support the hypothesis that selection of potato varieties under low agrochemical input conditions can deliver varieties that combine (i) late blight resistance/tolerance, (ii) nutrient use efficiency, and (iii) yield potential in organic farming systems. Full article

Potato scab, a global soil-borne disease caused by Streptomyces, is pivotal in developing resistant cultivars due to its complex resistance mechanisms. This study investigates the transcriptomic responses in potato to common scab using resistant variety CS10 and susceptible CS11 post S. scabie inoculation (0 d and 10 d, 12 cDNA libraries). Differential expression analysis identified 147 key DEGs (Differentially Expressed Genes) essential in disease recognition, signal transduction, and defense. GO (Gene Ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) enrichment analyses revealed several significant metabolic pathways, such as ADP binding, heme binding, chloroplast thylakoid membrane, photosynthesis, glutathione metabolism, and homologous recombination, among others. Notably, the correlation between chloroplast pathways (GO:0019745) and photosynthesis (map00195) highlights photosynthesis’s role in potato scab response, while the oxygen transport (GO:0031408)-related glutathione metabolism pathway (map00480) emphasizes antioxidant defenses. Furthermore, three potential resistance genes were validated: Ethylene Response Factor ERF010 (LOC102589042), Disease Resistance Protein RPP13 (LOC102605863), and Cytochrome P450 83B1 (LOC102604056), demonstrating the linkage between metabolic pathways and pathogen response. These findings offer insights into potato’s molecular resistance mechanisms against potato scab, supporting the breeding of resistant varieties and comprehensive disease management, thus advancing sustainable agriculture. Full article

For potato crops, host resistance is currently the most effective and sustainable tool to manage diseases caused by the plasmodiophorid Spongospora subterranea. Arguably, zoospore root attachment is the most critical phase of infection; however, the underlying mechanisms remain unknown. This study investigated the potential role of root-surface cell-wall polysaccharides and proteins in cultivars resistant/susceptible to zoospore attachment. We first compared the effects of enzymatic removal of root cell-wall proteins, N-linked glycans and polysaccharides on S. subterranea attachment. Subsequent analysis of peptides released by trypsin shaving (TS) of root segments identified 262 proteins that were differentially abundant between cultivars. These were enriched in root-surface-derived peptides but also included intracellular proteins, e.g., proteins associated with glutathione metabolism and lignin biosynthesis, which were more abundant in the resistant cultivar. Comparison with whole-root proteomic analysis of the same cultivars identified 226 proteins specific to the TS dataset, of which 188 were significantly different. Among these, the pathogen-defence-related cell-wall protein stem 28 kDa glycoprotein and two major latex proteins were significantly less abundant in the resistant cultivar. A further major latex protein was reduced in the resistant cultivar in both the TS and whole-root datasets. In contrast, three glutathione S-transferase proteins were more abundant in the resistant cultivar (TS-specific), while the protein glucan endo-1,3-beta-glucosidase was increased in both datasets. These results imply a particular role for major latex proteins and glucan endo-1,3-beta-glucosidase in regulating zoospore binding to potato roots and susceptibility to S. subterranea. Full article

The phytotoxin thaxtomin A (TA) is the key pathogenicity factor synthesized by the bacteria Streptomyces scabiei, the main causal agent of common scab of potato (Solanum tuberosum L.). TA treatment of potato tuber flesh produces a brown color that was attributed to necrosis. The intensity of TA-induced browning was generally thought to correlate with potato sensitivity to the disease. In this study, we found that TA-induced browning was much more intense in the potato tuber flesh of the common scab moderately resistant variety Russet Burbank (RB) than that observed in tubers of the disease-susceptible variety Yukon Gold (YG). However, there was no significant difference in the level of TA-induced cell death detected in both varieties, suggesting that tubers response to TA does not correlate with the level of sensitivity to common scab. TA-treated potato tuber tissues accumulated significantly higher levels of phenolic compounds than untreated controls, with a higher phenol content detected in RB TA-treated tissues than in those of YG. Browning was associated with a significant induction of the expression of genes of the phenylpropanoid pathway in RB tubers, indicating that TA activated this metabolic pathway. These results suggest that tuber flesh browning induced by TA is due to the accumulation of phenolic compounds. These phenolics may play a role in the protection of potato tubers against S. scabiei. Full article

Potato common scab (CS) is a worldwide soil-borne disease that severely reduces tuber quality and market value. We observed that foliar application of tryptophan (Trp) could induce resistance against CS. However, the mechanism of Trp as an inducer to trigger host immune responses is still unclear. To facilitate dissecting the molecular mechanisms, the transcriptome of foliar application of Trp and water (control, C) was compared under Streptomyces scabies (S) inoculation and uninoculation. Results showed that 4867 differentially expressed genes (DEGs) were identified under S. scabies uninoculation (C-vs-Trp) and 2069 DEGs were identified under S. scabies inoculation (S-vs-S+Trp). Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses indicated that Trp induced resistance related to the metabolic process, response to stimulus, and biological regulation. As phytohormone metabolic pathways related to inducing resistance, the expression patterns of candidate genes involved in salicylic acid (SA) and jasmonic acid/ethylene (JA/ET) pathways were analyzed using qRT-PCR. Their expression patterns showed that the systemic acquired resistance (SAR) and induced systemic resistance (ISR) pathways could be co-induced by Trp under S. scabies uninoculation. However, the SAR pathway was induced by Trp under S. scabies inoculation. This study will provide insights into Trp-induced resistance mechanisms of potato for controlling CS, and extend the application methods of Trp as a plant resistance inducer in a way that is cheap, safe, and environmentally friendly. Full article

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. Full article

Potatoes contain antioxidants such as flavonoids, carotenoids and ascorbic acid. High level consumption worldwide makes potato a valuable source of phytonutrients. Developing new potato varieties with high nutritional value in combination with resistance to pathogens is an important task. In this study, 25 interspecific potato hybrids with resistance to Synchytrium endobioticum, common scab, silver scab, rhizoctonia, nematodes and PVY were evaluated for total phenolics, total flavonoids, total carotenoids, ascorbic acid contents and antioxidant activity. The identification of the dominant allele related with yellow flesh color at the Chy locus was also performed by the specific CAPS marker. Total protein content was detected and ranged from 8.19 ± 0.59 to 30.17 ± 4.56 mg/g dry weight (DW). Total starch and total carbohydrate contents were in the range of 9.0–21.0% and 73.21 ± 20.94–676.36 ± 195.28, respectively. Total phenolic content of hybrids varied from 8.45 to 82.75 mg/100 g, and total flavonoids content—from 0.64 to 9.67 mg/100 g DW. It is possible to distinguish samples with high protein and carbohydrate contents, high level of substances with antioxidant activity and characterized by resistance to pathogens. Quality evaluation has shown that some of the samples have a high potential for processing and chip production in combination with high eating qualities. These samples can be used in breeding programs to develope varieties resistant to pathogens and with high nutritional value. Full article

Streptomyces scabies is a Gram-positive bacterial pathogen that causes common scab disease to several crops, particularly in the potato. It is a soil borne pathogen, a very devastating scab pathogen and difficult to manage in the field. Streptomyces has several species that cause common scab such as S. scabiei, S. acidiscabies, S. europaeiscabiei, S. luridiscabiei, S. niveiscabiei, S. puniciscabiei, S. reticuliscabiei, S. stelliscabiei, S. turgidiscabies, S. ipomoeae. Common scab disease harmfully affects potato economic and market value due to the presence of black spots on the tuber. Owing to its genetic diversity and pathogenicity, the determination of pathogen presence in potato fields is still challenging. In this study, S. scabies genetic diversity was measured by surveying five potato-growing areas of Pakistan during the growing season 2019. A total of 50 Streptomyces isolates, including S. scabies, S. acidiscabies, S. griseoflavus were isolated and identified based on morphologic, biochemical and molecular analysis. Virulent confirmation assays confirmed ten virulent strains of Streptomyces spp. On the potato cultivars Cardinal and Santee. Among the Streptomyces species, S. scabies showed the highest scab index, followed by S. acidiscabies and S. griseoflavus by exhibiting the scab-like lesions on potato tubers. Ten potato cultivars were screened against these virulent isolates of Streptomyces. The Faisalabad white variety showed the highest scab index followed By Cardinal, Tourag, Kuroda, Santee, Lady Rosetta, Asterix, Diamant, Faisalabad red and Sadaf. Moreover, genetic diversity and pathogenicity of Streptomyces spp. on potato tubers were also likely diverse in different geographical regions and also potato cultivars. This study represents a contribution to understanding the local interaction between potatoes and Streptomyces spp. in Pakistan. It will aid in supporting a solution for the management of this pathogen around the world. Full article