Sequence analysis of the chromosome region harboring the sequence-tagged site (STS) markers YES3-3A and YES3-3B for Rysto, a gene responsible for extreme resistance to Potato virus Y (PVY) in potato, ...was performed in tetraploid potato 'Barbara' (Rrrr) and 'AC Chaleur' (rrrr) as well as their progeny selections. Three and two sequence variants were identified in Barbara resistant (R) selections and AC Chaleur susceptible (S) selections, respectively. Further analysis indicates that the variant with a 21-nucleotide (nt) deletion is likely the chromosome copy harboring the STS markers. Two primer pairs, one targeting the region containing a 20-nt deletion and the other targeting the region anchoring the YES3-3A reverse primer, were designed. As anticipated, pair one produced two visible fragments in Barbara-R bulk and one visible fragment in AC Chaleur-S bulk; pair two produced one visible fragment in all samples. When subjected to high-resolution melting (HRM) analysis, two distinct melting profiles for R and S samples were observed. Analysis of 147 progeny of Barbara × AC Chaleur revealed 72 and 75 progeny with R and S melting profiles, respectively, which was consistent with YES3-3A and YES3-3B assays and phenotyping analysis, thus demonstrating the potential of HRM profiles as novel molecular markers for Rysto. The efficacy of the newly developed HRM markers for high-throughput marker-assisted selection for Rysto-conferred resistance to PVY was validated further with three populations involving Barbara as the R parent.
Virus-infected plants show strong morphological and physiological alterations. Many physiological processes in chloroplast are affected, including the plastidic isoprenoid biosynthetic pathway the ...2C-methyl-D-erythritol-4-phosphate (MEP) pathway; indeed, isoprenoid contents have been demonstrated to be altered in virus-infected plants. In this study, we found that the levels of photosynthetic pigments and abscisic acid (ABA) were altered in Potato virus Y (PVY)-infected tobacco. Using yeast two-hybrid assays, we demonstrated an interaction between virus protein PVY helper component-proteinase (HC-Pro) and tobacco chloroplast protein 1-deoxy-D-xylulose-5-phosphate synthase (NtDXS). This interaction was confirmed using bimolecular fluorescence complementation (BiFC) assays and pull-down assays. The Transket_pyr domain (residues 394-561) of NtDXS was required for interaction with HC-Pro, while the N-terminal region of HC-Pro (residues 1-97) was necessary for interaction with NtDXS. Using in vitro enzyme activity assays, PVY HC-Pro was found to promote the synthase activity of NtDXS. We observed increases in photosynthetic pigment contents and ABA levels in transgenic plants with HC-Pro accumulating in the chloroplasts. During virus infection, the enhancement of plastidic isoprenoid biosynthesis was attributed to the enhancement of DXS activity by HC-Pro. Our study reveals a new role of HC-Pro in the host plant metabolic system and will contribute to the study of host-virus relationships. Virus-infected plants show severe symptoms, such as chlorosis and necrosis associated with changes in chloroplast structure and function. The metabolism of various isoprenoids is also influenced concurrently. As one of the isoprenoids, the accumulations of ABA have been reported in various virus infections, but the reason for the increase is still unclear. In our study, the interaction between virus protein HC-Pro and host protein NtDXS (a limiting enzyme in MEP pathway) was proved to be a key factor. Our study revealed a new role of HC-Pro in host plants metabolism system and will contribute to the study of host-virus relationships.
To find efficient and broad-spectrum viral agents, a series of purine nucleoside derivatives containing sulfa ethylamine moieties was designed and synthesized, and their antiviral activities against ...tobacco mosaic virus (TMV), cucumber mosaic virus (CMV), and potato virus Y (PVY) were evaluated. Some target compounds displayed good antiviral activities. Among them, compound 3 showed excellent protective activity against CMV and PVY with 50% effective concentration values (EC50) of 137 and 209 μg/mL, respectively, which were better than that of the control agent ningnanmycin (508 and 431 μg/mL). Moreover, the EC50 value of compound 3 for the inactivating activity against TMV was 48 μg/mL, which was better than that of ningnanmycin (88 μg/mL). In addition, compound 3 not only destroyed the structure of the TMV virus but also had a good interaction with the coat protein of the TMV virus. Therefore, compound 3 may further destroy the structure of the virus by binding to the coat protein of the TMV virus, thereby weakening the infectivity of the virus.
Potato virus Y (PVY) is one of the most important constraints to potato production worldwide. There is an increasing occurrence of recombinant PVY strains PVYNTN and PVYN-Wi and a decline in the ...incidence of the nonrecombinant PVYO. We hypothesized that this may be due to the ability of these recombinant strains to antagonize and/or outcompete PVYO in mixed infections. To determine this, we investigated interactions between PVYO and three recombinant PVY strains common in North America: PVYNTN, PVYN-Wi, and PVYN:O. Overall, our study showed that these interactions are tissue-dependent. Specifically, PVYNTN, the main causal agent of potato tuber necrotic ringspot disease (PTNRD), was found to be more adaptable than PVYO, especially in potato leaves due, at least in part, to the Ny gene that confers hypersensitive resistance (HR) to PVYO. Furthermore, PVYN-Wi was found to repress PVYO in potato tubers but act synergistically in potato leaves. The PVYO-induced foliage necrosis in cultivar ‘Ranger Russet’ was observed to be more severe in plants co-infected by PVYN-Wi and PVYN:O, respectively, resulting in plant death. Strikingly, this PVYO -induced necrosis was suppressed by PVYNTN in doubly infected plants. These interactions may, at least partially, explain the decreasing incidence of PVYO in United States potato production regions, especially given that many cultivars contain the Ny gene, which likely limits PVYO enabling PVYNTN and PVYN-Wi to outcompete. We also found that replication and cell-to-cell movement of these PVY strains in tubers at 4 °C was similar to levels at ambient temperature.
The importance of potato has increased dramatically in Indonesia over the last three decades. During this period, 'Granola', a potato cultivar originally from Germany, has become the most common ...cultivar for fresh consumption in Indonesia. In August 2014, a survey was conducted in Sulawesi, where potato fields cultivated with Granola and its selection, 'Super John', were sampled for Potato virus Y(PVY) presence. PVY was found in Sulawesi for the first time. Samples determined to be positive for PVY were subsequently typed to strain using reverse-transcription polymerase chain reaction assays. All PVY isolates sampled were identified as PVY super(NTN) recombinants, with three recombination junctions in P3, VPg, and CP regions of the genome. Three local PVY isolates were subjected to whole-genome sequencing and subsequent sequence analysis. The whole genomes of the Indonesian PVY super(NTN) isolates I-6, I-16, and I-17 were found to be closely related to the European PVY super(NTN)-A. This recombinant type was shown previously to cause potato tuber necrotic ringspot disease (PTNRD) in susceptible potato cultivars. The dependence of potato farmers on mostly a single cultivar, Granola, may have given a competitive advantage to PVY super(NTN) over other PVY strains, resulting in the predominance of the PVY super(NTN) recombinant. The dominance of PVY super(NTN) in Sulawesi, and possibly in Indonesia as a whole, represents a potential risk to any newly introduced potato cultivar to the country, especially cultivars susceptible to PTNRD.
Potato (
) plants are exposed to diverse environmental stresses, which may modulate plant-pathogen interactions, and potentially cause further decreases in crop productivity. To provide new insights ...into interactive molecular responses to heat stress combined with virus infection in potato, we analyzed expression of genes encoding pathogenesis-related (PR) proteins markers of salicylic acid (SA)-mediated plant defense and heat shock proteins (HSPs), in two potato cultivars that differ in tolerance to elevated temperatures and in susceptibility to potato virus Y (PVY). In plants of cv. Chicago (thermosensitive and PVY-susceptible), increased temperature reduced
gene expression and this correlated with enhancement of PVY infection (virus accumulation and symptom production). In contrast, with cv. Gala (thermotolerant and PVY resistant), which displayed a greater increase in
gene expression in response to PVY infection, temperature affected neither PR transcript levels nor virus accumulation.
genes were induced by elevated temperature in both cultivars but to higher levels in the thermotolerant (Gala) cultivar. PVY infection did not alter expression of
genes in the Gala cultivar (possibly because of the low level of virus accumulation) but did induce expression of
and
in the susceptible cultivar (Chicago). These findings suggest that responses to heat stress and PVY infection in potato have some common underlying mechanisms, which may be integrated in a specific consolidated network that controls plant sensitivity to multiple stresses in a cultivar-specific manner. We also found that the SA pre-treatment subverted the sensitive combined (heat and PVY) stress phenotype in Chicago, implicating SA as a key component of such a regulatory network.
Novel purine nucleoside derivatives containing a sulfonamide moiety were prepared, as well as their antiviral activities against potato virus Y (PVY), cucumber mosaic virus (CMV), and tobacco mosaic ...virus (TMV) were evaluated. The antiviral mechanisms of the compounds were investigated. Results showed that most of the compounds had good antiviral activities. Compound 5 at 500 μg/mL exhibited excellent curative and protective activities of 52.5% and 60.0% and of 52.0% and 60.2% for PVY and CMV, respectively, which are higher than those of ningnanmycin (48.1%, 49.6%; 45.3%, 47.7%), ribavirin (38.3%, 48.2%; 40.8%, 45.5%), and chitosan oligosaccharide (32.5%, 33.8%; 35.1%, 34.6%). Moreover, compound 5 displayed good inactivating activity against TMV, with an EC50 value of 48.8 μg/mL, which is better than that of ningnanmycin (84.7 μg/mL), ribavirin (150.4 μg/mL), and chitosan oligosaccharide (521.3 μg/mL). The excellent antiviral activity of compound 5 is related to its immune induction effect which can regulate the physiological and biochemical processes in plants, including defense-related enzyme activities, defense-related genes, and photosynthesis-related proteins. These results indicate that purine nucleoside derivatives containing a sulfonamide moiety are worthy of further research and development as new antiviral agents.
Summary
Amino acid substitutions in the eukaryotic translation initiation factor 4E (eIF4E) result in recessive resistance to potyviruses in a range of plant species, including Capsicum spp. ...Correspondingly, amino acid changes in the central part of the viral genome‐linked protein (VPg) are responsible for the potyvirus’s ability to overcome eIF4E‐mediated resistance. A key observation was that physical interaction between eIF4E and the VPg is required for viral infection, and eIF4E mutations that cause resistance prevent VPg binding and inhibit the viral cycle. In this study, polymorphism analysis of the pvr2‐eIF4E coding sequence in a worldwide sample of 25 C. annuum accessions identified 10 allelic variants with exclusively non‐synonymous variations clustered in two surface loops of eIF4E. Resistance and genetic complementation assays demonstrated that pvr2 variants, each with signature amino acid changes, corresponded to potyvirus resistance alleles. Systematic analysis of the interactions between eIF4E proteins encoded by the 10 pvr2 alleles and VPgs of virulent and avirulent potato virus Y (PVY) and tobacco etch virus (TEV) strains demonstrated that resistance phenotypes arose from disruption of the interaction between eIF4E and VPg, and that viral adaptation to eIF4E‐mediated resistance resulted from restored interaction with the resistance protein. Complementation of an eIF4E knockout yeast strain by C. annuum eIF4E proteins further shows that amino acid changes did not impede essential eIF4E functions. Altogether, these results argue in favour of a co‐evolutionary ‘arms race’ between Capsicum eIF4E and potyviral VPg.
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•Hydrodynamic cavitation inactivates PVY in water samples after 500 passes or less.•Hydrodynamic cavitation disrupts the viral capsid.•Hydrodynamic cavitation induces minor damage in ...the viral genome.•Mechanical effects of cavitation likely play the main role in the PVY inactivation.•Hydrodynamic cavitation can be used for inactivation of waterborne viruses.
Waterborne plant viruses can destroy entire crops, leading not only to high financial losses but also to food shortages. Potato virus Y (PVY) is the most important potato viral pathogen that can also affect other valuable crops. Recently, it has been confirmed that this virus is capable of infecting host plants via water, emphasizing the relevance of using proper strategies to treat recycled water in order to prevent the spread of the infectious agents. Emerging environmentally friendly methods such as hydrodynamic cavitation (HC) provide a great alternative for treating recycled water used for irrigation. In the experiments conducted in this study, laboratory HC based on Venturi constriction with a sample volume of 1 L was used to treat water samples spiked with purified PVY virions. The ability of the virus to infect plants was abolished after 500 HC passes, corresponding to 50 min of treatment under pressure difference of 7 bar. In some cases, shorter treatments of 125 or 250 passes were also sufficient for virus inactivation. The HC treatment disrupted the integrity of viral particles, which also led to a minor damage of viral RNA. Reactive species, including singlet oxygen, hydroxyl radicals, and hydrogen peroxide, were not primarily responsible for PVY inactivation during HC treatment, suggesting that mechanical effects are likely the driving force of virus inactivation. This pioneering study, the first to investigate eukaryotic virus inactivation by HC, will inspire additional research in this field enabling further improvement of HC as a water decontamination technology.
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