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PubMed2006

Potide-G derived from potato (Solanum tuberosum L.) is active against potato virus YO (PVYO) infection.

A PVYO virus-resistant potato (Solanum tuberosum L. cv. Golden Valley) was identified, and further, from its tubers, a small (5.57 kDa) antiviral peptide potide-G was isolated. Application of potide-G on virus susceptible potato (cv. Winter valley) expressed robust resistance to PVYO infection and showed no virus infected morphology. We found that PVYO infection spreads up completely within 3 days post inoculation (dpi) in susceptible cultivar. PVYO was more accumulated toward the basal leaves, when infection occurred longer. Combined results of morphology of PVYO infection, ELISA, RT-PCR, and real-time PCR showed the resistance to the PVYO infection depends on the expression of Ry gene. Indeed, the real-time PCR result showed that the Ry gene up-regulated to 3 times higher in PVYO infected cv. Golden valley. Golden crude protein was found to be active against PVYO infection in the in vivo test. In addition, application of potide-G in a virus susceptible potato potently reduced the viral infection actively with 50 times lower concentration than that of the Golden protein. Further identification of a host-specific resistant gene in a plant and the peptide derived from it offers new opportunities for the development of novel bio-pesticides against plant virus.

Capsid Proteins↗

PubMed1992

Increased resistance to potato virus X and preservation of cultivar properties in transgenic potato under field conditions.

During the last three years we performed field trials to assess levels of resistance against potato virus X (PVX) and changes in intrinsic properties of the potato cultivars Bintje and Escort upon the introduction of the PVX coat protein (CP) gene. Analysis of leaf and tuber samples collected in the field at two week intervals revealed a stable expression of the PVX CP gene throughout the growing season. This resulted in a large decrease in PVX incidence among clonal progeny obtained from previously infected Bintje and Escort clones. Based on evaluation of 50 defined morphological characteristics, tuber yield and grading, 81.8% of the Escort and 17.9% of the Bintje derived transgenic clones proved to be true to type. Overall lightsprout morphology was a useful criterion for the early detection of deviant transgenic clones. Using the polymerase chain reaction (PCR) with convergent primers spanning transgenic sequences, true to type clones could be distinguished unambiguously from the corresponding untransformed cultivars. Clear distinctions between independent transgenic clones could be made by inverted PCR (IPCR) diagnosis revealing integration-specific border fragments. These results demonstrate the commercial feasibility of improving potato cultivars by selectively adding new traits while preserving intrinsic properties, and the possibility of unambiguously identifying independent transgenic cultivars.

Base Sequence↗

PubMed2001

A review of host major-gene resistance to potato viruses X, Y, A and V in potato: genes, genetics and mapped locations.

In view of modern developments in the technologies available for breeding potatoes for resistance to virus diseases, it is timely to review the host major genes that confer resistance, in Solanum species, to potato viruses X, Y, A and V (the viruses for which the resistance genes have been most extensively studied). Over the course of 60 years, many such genes in Solanum species have been characterized: a comprehensive list is presented. Inheritance studies are reviewed, including linkage studies and molecular mapping, and the positions of resistance genes mapped so far are listed. It is apparent from recent research that disease resistance genes are often clustered in particular regions of the chromosomes; the significance of these resistance gene clusters is discussed. The information presented will be useful for potato breeding, and for genetic and mapping studies and gene cloning.

Chromosome Mapping↗

PubMed1995

The coat protein of potato virus X is a strain-specific elicitor of Rx1-mediated virus resistance in potato.

The Rx1 gene in potato confers extreme resistance to potato virus X (PVX). To investigate the mechanism and elicitation of Rx resistance, protoplasts of potato cv. Cara (Rx1 genotype) and Maris Bard (rx1 genotype) were inoculated with PVX and tobacco mosaic virus (TMV). At 24 h post-inoculation in Maris Bard protoplasts there was at least 100-fold more PVX RNA than in protoplasts of Cara. TMV RNA accumulated to the same level in both types of protoplast. However, when the TMV was inoculated together with PVX the accumulation of TMV RNA was suppressed in the Cara (Rx1 genotype) protoplasts to the same extent as PVX. The Rx1 resistance also suppressed accumulation of a recombinant TMV in which the coat protein gene was replaced with the coat protein gene of PVX. It is therefore concluded that Rx1-mediated resistance is elicited by the PVX coat protein, independently of any other proteins encoded by PVX. The domain of the coat protein with elicitor activity was localized by deletion and mutation analysis to the structural core of a nonvirion form of the coat protein.

Base Sequence↗

PubMed2000

An Ry-mediated resistance response in potato requires the intact active site of the NIa proteinase from potato virus Y.

Ry confers extreme resistance to all strains of potato virus Y (PVY). To identify the elicitor of the Ry-mediated resistance against PVY in potato, we expressed each of the PVY-encoded proteins in leaves of PVY-resistant (Ry) and -susceptible (ry) plants. For most of the proteins tested, there was no evident response. However, when the NIa proteinase was expressed in leaves of Ry plants, there was a hypersensitive response (HR). Proteinase active site mutants failed to induce the Ry-mediated response. The HR was also induced by the NIa proteinase from pepper mottle virus (PepMoV), which has the same cleavage specificity as the PVY enzyme, but not by the tobacco etch virus (TEV) or the potato virus A (PVA) proteinases that cleave different peptide motifs. Based on these results, we propose that Ry-mediated resistance requires the intact active site of the NIa proteinase. Although the structure of the active proteinase could have elicitor activity, it is possible that this proteinase releases an elicitor by cleavage of a host-encoded protein. Alternatively, the proteinase could inactivate a negative regulator of the Ry-mediated resistance response.

Amino Acid Sequence↗

PubMed1990

[Measuring energy turnover in the adult swine during feeding of rations with potato starch, potatoes, beets, pressed shreds and coarse fodder as supplements to a basic ration. 1. Energy turnover and energy utilization].

25 rations with a wide variation of the content of various carbohydrates (crude fibre 36-185; water-soluble carbohydrates 25-306, starch 272-683 g/kg DM) were fed to male castrates (n = 8) of a live weight between 90 and 180 kg, and energy metabolism was measured. The rations were composed of a cereal basic ration and various feed-stuffs (potato starch-raw and soaked) potatoes (raw and steamed), sugar beet and products from it, maize pellets, dried roughage lucerne, clover, lupin, grass, rye straw meal) as supplements. The digestibility and metabolisability of the energy of the rations ranged between 88 and 62 or 86 and 60% resp. Between 2 and 4% of the consumed energy were lost in urine. The partial utilization of the metabolizable energy of the rations varied between 80% (processed supplement of potato starch) and 52% (supplement of rye straw). The rations with supplements of dried roughage were relatively well energetically utilized-between 63 and 70%. A regressively calculated difference of 17%-units was regressively calculated between the utilization of metabolizable energy of either precaecal or postileal origin.

Animal Feed↗

PubMed2005

Aspects of potato leafhopper (Homoptera: Cicadellidae) biology on Solanum berthaultii and other potato genotypes.

Survival of nymphs and adult males and females of potato leafhopper, Empoasca fabae (Harris), on six potato (Solanum spp.) genotypes with varied levels of resistance was evaluated and related to type, density, and droplet/head size of foliar glandular trichomes. Survival was greater on Solanum tuberosum cultivars ('Allegany' and 'Elba') compared with accessions of the wild S. berthaultii (PI 473331 and PI 473334). The barrier provided by glandular trichomes may affect survival of E.fabae by restricting nymph and adult feeding. PI 473331 was the most pubescent host, bearing type A and type B trichomes and the most unsuitable host for E. fabae. Allegany possesses leaflets with low trichome densities and small gland diameter and was the most suitable host for adult E. fabae survival. Females generally had higher survival rates than males. Nymphal and adult leafhoppers differed greatly in their survival rates, particularly on S. tuberosum x S. berthaultii hybrids (Q174-2 and NY123). Interestingly, nymphs had longer (190 d) mean lethal time (LT50) than adults (31 d) when held on Q174-2, and a lower LT50 (19 d) when held on NY123 compared with adults (104 d). Starvation, dehydration, or both were likely associated with mortality of nymphs confined on PI 473331 and PI 473334. Nymphs on these accessions died at a comparable rate to those confined on a starvation treatment and more rapidly than those supplied with water only, sucrose solution or other potato genotypes. Darkened trichome exudates were observed on insects held on PI 473331 and PI 473334, consistent with previous reports that glandular trichomes of S. berthaultii contain phenolic oxidation chemistry. This study aids in the identification of the probable mechanisms of resistance to E. fabae used by S. berthaulti and its hybrids with S. tuberosum.

Animals↗

PubMed1997

Expression of the potato leafroll virus ORF0 induces viral-disease-like symptoms in transgenic potato plants.

The role of the open reading frame 0 (ORF0) of luteoviruses in the viral infection cycle has not been resolved, although the translation product (p28) of this ORF has been suggested to play a role in host recognition. To investigate the function of the potato leafroll luteovirus (PLRV) p28 protein, transgenic potato plants were produced containing the ORF0. In the lines in which the ORF0 transcripts could be detected by Northern (RNA) analysis, the plants displayed an altered phenotype resembling virus-infected plants. A positive correlation was observed between levels of accumulation of the transgenic transcripts and severity of the phenotypic aberrations observed. In contrast, potato plants transformed with a modified, untranslatable ORF0 sequence were phenotypically indistinguishable from wild-type control plants. These results suggest that the p28 protein is involved in viral symptom expression. Southern blot analysis showed that the transgenic plants that accumulated low levels of ORF0 transcripts detectable only by reverse transcription-polymerase chain reaction, contained methylated ORF0 DNA sequences, indicating down-regulation of the transgene provoked by the putatively unfavorable effects p28 causes in the plant cell.

Amino Acid Sequence↗

PubMed1991

Resistance in Solanum brevidens to both potato virus Y and potato virus X may be associated with slow cell-to-cell spread.

A series of experiments was carried out to investigate the nature of the resistance of the wild potato species, Solanum brevidens, to potato virus X (PVX) and potato virus Y (PVY). In vitro inoculation of leaf protoplasts of S. brevidens and the virus-susceptible dihaploid S. tuberosum genotype PDH40 with PVX or PVY using polyethylene glycol showed that protoplasts of both species were similar in susceptibility. However, examination of protoplasts prepared from the leaves of S. tuberosum and S. brevidens inoculated 2 to 5 weeks earlier showed that the percentage of PVX- and PVY-infected leaf cells of S. tuberosum were, respectively, 45- to 100-fold and about 1000-fold greater than the percentage of infected leaf cells of S. brevidens. These results suggest that resistance in S. brevidens to both PVX and PVY could be associated with slow cell-to-cell spread rather than with slow virus replication.

Disease Susceptibility↗

PubMed1993

Signal for potyvirus-dependent aphid transmission of potato aucuba mosaic virus and the effect of its transfer to potato virus X.

A British isolate of potato aucuba mosaic potexvirus (PAMV) was transmitted by aphids (Myzus persicae) which had fed previously on a source of potato Y potyvirus (PVY). Nucleotide sequence analysis of the PAMV coat protein gene indicated that amino acid residues 14 to 16 from the N terminus of the coat protein have the sequence DAG, which is also found in the coat proteins of potyviruses and is required for their aphid transmissibility. A recombinant virus isolate (TXPA7) was produced in which a segment of the coat protein gene of PAMV encoding the 40 N-terminal amino acids was inserted in the genome of potato X potexvirus (PVX) in place of the segment encoding the 28 N-terminal amino acids of PVX coat protein. This isolate, and a second similar recombinant (TXPA5) in which the DAG motif was changed to YTS, were mechanically transmissible to intact plants, in which they caused slightly milder symptoms than PVX. Particles of TXPA7 reacted in immunosorbent electron microscopy with PVX- and PAMV-specific antibodies and so were antigenically distinguishable from PAMV and PVX particles, which reacted only with their homologous antibody, and from TXPA5 particles, which reacted only with the PVX antibody. Recombinant TXPA7 was transmitted by aphids that had already fed on a source of PVY whereas TXPA5 and PVX were not. TXPA7 was not transmitted by aphids that had not fed on a PVY source. It is concluded that (i) the potyvirus-dependent aphid transmissibility of PAMV results from possession of a domain which includes the DAG motif and is located near the N terminus of the virus coat protein, and (ii) potyvirus-dependent aphid transmissibility can be conferred on PVX, a non-aphid-borne potexvirus, by substituting this domain for the N-terminal part of its coat protein.

Amino Acid Sequence↗

PubMed1997

Evidence for heterologous encapsidation of potato spindle tuber viroid in particles of potato leafroll virus.

The aphid Myzus persicae (Sulz.) was shown to transmit potato spindle tuber viroid (PSTVd) to potato clone DTO-33 from source plants doubly infected with potato leafroll virus (PLRV) and PSTVd. Transmission was of the persistent type and did not occur when the insects were allowed to feed on singly infected plants. Only low levels of PSTVd were associated with purified PLRV virions, but its resistance to digestion with micrococcal nuclease indicates that the viroid RNA is encapsidated within the PLRV particles. Epidemiological surveys carried out at three locations in China revealed a strong correlation between PSTVd infection and the presence of PLRV, suggesting that PLRV can facilitate PSTVd spread under field conditions.

Capsid↗

PubMed2000

Aphid transmission studies using helper component proteins of potato virus Y expressed from a vector derived from potato virus X.

The genes encoding the helper component (HC) proteins of two strains of Potato virus Y (PVY) were cloned and the proteins expressed from a vector derived from Potato virus X (PVX). The expressed HC contained six N-terminal histidine residues to facilitate purification by metal affinity chromatography. Approximately 2-4 microg/g of purified HC was obtained from leaves of Nicotiana benthamiana plants systemically infected by recombinant PVX. Preparations of the HC protein derived from PVY ordinary strain (PVY(o)) assisted aphid transmission of purified particles of PVY(o) and PVY strain C (PVY(c); a naturally occurring non-aphid transmissible strain of PVY which contains a defective HC), as well as Potato aucuba mosaic virus. The HC derived from PVY(c) contained the Glu-Ile-Thr-Cys (EITC) motif, and mutation of Glu (E) to Lys (K) enabled the mutant PVX-expressed preparations to assist virus transmission by aphids. Expression of HC protein from the PVX vector produced biologically active protein. This approach should facilitate further studies to elucidate more precisely the molecular mechanism of virus transmission by aphids.

Amino Acid Sequence↗

PubMed2001

Use of a vector based on Potato virus X in a whole plant assay to demonstrate nuclear targeting of Potato spindle tuber viroid.

Potato spindle tuber viroid (PSTVd) is a covalently closed circular RNA molecule of 359 nucleotides that replicates within the nucleus of host cells. To determine how this small, highly structured RNA enters the nucleus, we have developed a virus-based, whole plant in vivo assay that uses green fluorescent protein (GFP) as the reporter molecule. The coding region of GFP was interrupted by insertion of an intron derived from the intervening sequence 2 of the potato ST-LS1 gene. A cDNA copy of the complete PSTVd genome was, in turn, embedded within the intron, and this construct was delivered into Nicotiana benthamiana plants via a vector based on Potato virus X. The intron-containing GFP subgenomic RNA synthesized during virus infection cannot produce a functional GFP unless the RNA is imported into the nucleus, where the intron can be removed and the spliced RNA returned to the cytoplasm. The appearance of green fluorescence in leaf tissues inoculated with constructs containing a full-length PSTVd molecule embedded in the intron indicates that nuclear import and RNA splicing events did occur.

Active Transport, Cell Nucleus↗

PubMed1966

Isolation, Crystallization, and Partial Identification of Potato Factor II from Potato Tubers.

The isolation, crystallization, and partial identification of potato factor II, a stimulator from the chemically neutral fraction of potato extract, is described. The compound was originally found to stimulate elongation of dwarf peas grown under red light, a gibberellin bioassay. It melts between 137 degrees and 139 degrees . In paper chromatography it migrates to R(F) 0.62 in isopropyl alcohol: ammonium hydroxide: H(2)O (10:1:1, v/v). Based on infrared and NMR data, it does not contain a lactone ring and possibly possesses an amide radical and an OH(-) group, as well as many methylene radicals. Potato factor II may be similar to certain of the fatty acid derivatives previously reported to stimulate growth of excised sections, but it is unique in that it stimulates growth of intact plants. This effect points to the need for completely separating neutral from acid gibberellin-like substances when the latter are assayed on dwarf peas.

Journal Article↗

PubMed1994

Pseudothionin-St1, a potato peptide active against potato pathogens.

A 5-kDa polypeptide, pseudothionin Solanum tuberosum 1 (Pth-St1), which was active against Clavibacter michiganensis subspecies sepedonicus, a bacterial pathogen of potatoes, has been purified from the buffer-insoluble fraction of potato tubers by salt extraction and HPCL. Pth-St1 was also active against other potato pathogens tested (Pseudomonas solanacearum and Fusarium solani). The N-terminal amino acid sequence of this peptide was identical (except for a N/H substitution at position 2) to that deduced from a previously reported cDNA sequence (EMBL accession number X-13180), which had been misclassified as a Browman-Birk protease inhibitor. Pth-St1 did not inhibit either trypsin or insect alpha-amylase activities, and, in contrast with true thionins, did not affect cell-free protein synthesis or beta-glucuronidase activity. Northern-blot and tissue-print analyses showed that steady-state mRNA levels were highest in flowers (especially in petals), followed by tubers (especially in the epidermal cell layers and in leaf primordia), stems and leaves. Infection of leaves with a bacterial pathogen suspended in 10 mM MgCl2 switched off the gene, whereas mock inoculation with 10 mM MgCl2 alone induced higher mRNA levels.

Actinomycetales↗

PubMed2004

Replicase mediated resistance against potato leafroll virus in potato Desirée plants.

Potato leafroll virus (PLRV) is a major menace for the potato production all over the world. PLRV is transmitted by aphids, and until now, the only strategy available to control this pest has been to use large amounts of insecticides. Transgenic approaches involving the expression of viral replicases are being developed to provide protection for plants against viral diseases. The purpose of this study was to compare the protection afforded by the differential expression of PLRV replicate transgene in potato plants cv. Desirée, Plants were genetically modified to express the complete sense PLRV replicase gene. Two constructions were used, one containing the constitutive 35SCaMV promoter and the other the phloem-specific RolA promoter from Agrobacterium rhizogenes. Transgenic plants were infected with PLRV in vitro, using infested aphids. In plants in which 35SCaMV controlled the expression of the PLRV replicase gene, signs of infection were initially detected, although most plants later developed a recovery phenotype showing undetectable virus levels 40 days after infection. In turn, those plants with the RolA promoter displayed an initial resistance that was later overcome. Different molecular mechanisms are likely to participate in the response to PLRV infection of these two types of transgenic plants.

Enzyme Induction↗

PubMed2002

[Isolation of endophytic bacteria in potato and test of antagonistic action to bacterial ring rot of potato].

In this study, two hundred and forty bacterial strains were isolated from inner tissue of potato tubers collected from DaTong, TaiYuan and Inner Mongolia Autonomous regions. On the basis of antagonistic examination in vitro, fifty and five bacteria strains were characterized for antagonistic bacteria to ring rot of potato. It was 22.9 percentage of all bacteria strains. The biggest radius of suppression circle was 13 mm. Nine strains were chosen for their suppression of bacterial ring rot, blackleg and dry rot of potato. These strains were bacteriologically ideatified. Strain 118 was Pseudomonas fluorescens biovar V. Strain 110 was Bacillus pumilus. Strain 085 was Bacillus stearothermophilus. Strain 069 was Erwinia herbicola. Strain 043 was Xanthomomas fragariae. Strain 116 was Curtobacterium. Strains A-10' and T3 were Bacillus. Strain H1-6 was Pseudomonas fluorescens.

Bacillus↗

PubMed1987

Purification and properties of lectin from potato tubers and leaves; interaction with acid phosphatase from potato tuber.

The haemagglutination activity of lectin, (STA) was determined during vegetation of potatoes (Solanum tuberosum var. Uran). Traces of haemagglutination activity were found in young stalks and first leaves. In the next leaves the maximal activity appeared after 6-8 weeks of vegetation and, simultaneously with the decrease in leaves it appeared in young tubers (at the time of their differentiation from stolons), reaching the maximum in the 18th week of vegetation. Lectins from potato tubers and leaves were extracted with acetate buffer, pH 3.6, salted out with ammonium sulphate, and purified alternatively by affinity chromatography on GlcNAc-Spheron or by adsorption on trypsinated and glutaraldehyde-fixed rabbit erythrocytes. Chromatography on Sephadex G-200 was used for preparative separation of isomeric forms. In the tubers four isolectins were found, differeing in molecular mass, pI values, content of sugars and haemagglutination activity. Two of these forms were isolated in homogeneous form: a heavy dimeric form, Mr 130,000-142,000 containing 59.6% of sugars (including 28.8% arabinose, 6.9% galactose, 16.5% glucose, 1.6% xylose and 3.1% mannose), and a light monomeric form. of Mr 21,000-22,000, containing 20% of neutral sugars (2.5% of pentoses and 17.5% of hexoses). From leaves, a single heavy dimeric lectin of Mr 136,000, containing 14.3% of neutral sugars was isolated. The effect of tuber isolectin on the activity, pH optima and heat-stability of the potato acid phosphatase has been described.

Acid Phosphatase↗