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PubMedDate not supplied

Molecular analysis of potato virus X isolates in relation to the potato hypersensitivity gene Nx.

The coat protein gene of potato virus X is known to affect the outcome of interactions between different strains of the virus and potato plants carrying the Nx resistance gene. To analyze the role of the coat protein in interactions with Nx hosts, we used the potato virus X strain PVXDX, which induces a hypersensitive response on potato cultivars carrying the Nx resistance gene and the strain PVXDX4, which was originally derived from PVXDX and which overcomes Nx-mediated resistance. Sequencing of cloned coat protein genes representing the strains PVXDX and PVXDX4 showed that they differed at a single nucleotide. This change results in the substitution of glutamine-78 in the PVXDX coat protein for proline in PVXDX4. We constructed hybrid viral genomes by replacing the coat protein gene of a full-length clone of isolate PVXUK3 with the corresponding sequence from either PVXDX or PVXDX4. Progeny virus, derived from in vitro transcripts of these hybrid clones, showed that the single nucleotide difference between the coat protein genes of isolates PVXDX and PVXDX4 was sufficient to alter the outcome of the interaction between the virus and potato plants carrying the resistance gene Nx. Additional coat protein mutants generated in planta from transcript-derived inocula induced an intermediate host response on Nx potato cultivars which is influenced by the presence of a second, PVX-specific, resistance gene in the host plant genome.

Base Sequence↗
PubMed1998

A hypersensitive response-like mechanism is involved in resistance of potato plants bearing the Ry(sto) gene to the potyviruses potato virus Y and tobacco etch virus.

Potato plants carrying the Ry(sto) gene from Solanum stoloniferum are extremely resistant to a number of potyviruses, but it is not known at what stage of infection the resistance is expressed. The resistance may be due to Ry(sto) or to a closely linked gene. In this investigation, we used potato virus Y (PVY) and a tobacco etch virus construct that encodes beta-glucuronidase (TEV-GUS) to monitor virus infections of potato plants. Systemic spread of either virus in resistant potato plants was not detectable by serology, RT-PCR, GUS assay or bioassay although each replicated in the initially infected cells of leaves from resistant potato cultivars and was transported into neighbouring cells. However, 3 days post-inoculation (p.i.) a necrotic reaction set in that stopped movement and accumulation of both viruses by 7 days p.i. The resistance reaction (probably a hypersensitive reaction) became visible as necrotic streaks on veins on the lower leaflet surfaces of some potato cultivars carrying the Ry(sto) gene and may be elicited by a common potyviral gene product.

Genes, Plant↗
PubMed2000

Evaluation of potato tuber moth (Lepidoptera: Gelechiidae) resistance in tubers of Bt-cry5 transgenic potato lines.

The potato tuber moth, Phthorimaea operculella (Zeller), in tropical and subtropical countries, is the most destructive pest of potato, Solanum tuberosum L. The larvae attack foliage and tubers in the field and in storage. The purpose of this study was to evaluate the efficacy of a Bt-cry5 transgene to control the potato tuber moth in tuber tissues. Tuber bioassays using stored (11-12 mo old) and newly harvested tubers of Bt-cry5-Lemhi Russet and Bt-cry5-Atlantic potato lines showed up to 100% mortality of 1st instars. Mortality was lowest in the newly harvested tubers of Bt-cry5-Atlantic lines (47.1-67.6%). Potato tuber moth mortality was 100% in the Bt-cry5-Spunta lines that were transformed with Bt-cry5 gene controlled by the CaMV 35S promoter (pBIML5 vector) and in 2 of 3 lines transformed with Bt-cry5 gene controlled by the Gelvin super promoter (pBIML1 vector). The transgenic Spunta lines expressing Bt-cry5 controlled by the patatin promoter (pBMIL2 vector) showed the lowest tuber moth mortality (25.6 and 31.1%). The Bt-cry5 transgenic lines with high tuber expression of B. thuringiensis have value in an integrated pest management system to control potato tuber moth.

Animals↗
PubMed2004

Colorado potato beetles compensate for tomato cathepsin D inhibitor expressed in transgenic potato.

We reported earlier the importance of digestive cathepsin D-like activity for initiating dietary protein hydrolysis in Colorado potato beetle, Leptinotarsa decemlineata Say [Brunelle et al. (1999) Arch. Insect Biochem. Physiol. 42:88-98]. We assessed here whether transgenic lines of potato (Solanum tuberosum L.) expressing a cathepsin D inhibitor (CDI) from tomato would show resistance to the beetle, or if the insect would compensate for the loss of cathepsin D activity after ingesting the recombinant inhibitor. Transgenic potato lines expressing tomato CDI were developed by Agrobacterium tumefaciens genetic transformation, and selected based on their relative amount of CDI. After confirming the absence of detectable visible effects of CDI on the plant's phenotype, diet assays with control and transgenic lines were carried out to assess the impact of the inhibitor on growth and development of the insect. Leaf consumption, relative growth rate, molting incidence, and digestive protease activity were monitored at 12-h intervals over 132 h for 3rd-instar larvae provided with transgenic potato foliage. Leaf consumption and relative growth rate were slightly reduced during the first 12 h for larvae fed CDI, but no significant differences were observed thereafter. In contrast, time for molting to the 4th larval stage was significantly longer for larvae fed modified plants, with developmental delays of approximately 10 h (0.5 day) compared to control larvae. Recombinant CDI also had an impact on the insect's digestive physiology, readily inducing overproduction of digestive proteases (rubiscases), followed by a gradual decrease of total and pepstatin-sensitive activity. Overall, these observations show the ability of Colorado potato beetle to compensate for the loss of cathepsin D activity by modulating its digestive protease complement in response to aspartate-type inhibitors in the diet. From a practical viewpoint, these data stress the importance of devising improved strategies for the effective inhibition of insect digestive proteinases in vivo, based on the use of hybrid inhibitors active against different protease classes.

Animal Feed↗
PubMed1993

Genetically improved potatoes: protection from damage by Colorado potato beetles.

Russet Burbank potato plants have been genetically improved to resist insect attack and damage by Colorado potato beetles (Leptinotarsa decemlineata (Say)) by the insertion of a cryIIIA gene encoding the insect control protein of Bacillus thuringiensis var. tenebrionis. A modified gene that dramatically improved plant expression of this protein was utilized. Its expression in Russet Burbank potato plants resulted in protection from damage by all insect stages in the laboratory and in dramatic levels of protection at multiple field locations. Analysis of these genetically modified potatoes indicated that they conform to the standards for Russet Burbank potatoes in terms of agronomic and quality characteristics including taste.

Amino Acid Sequence↗
PubMed1993

Transgenic potato plants overexpressing the pathogenesis-related STH-2 gene show unaltered susceptibility to Phytophthora infestans and potato virus X.

The STH-2 gene is rapidly activated in potato leaves and tubers following elicitation or infection by Phytophthora infestans. However, its biochemical function remains unknown. In order to ascertain if STH-2 protein is directly involved in the defense of potato against pathogens, the STH-2 coding sequence under the control of the CaMV 35S promoter was introduced into potato plants. Transgenic plants expressing the STH-2 gene were analyzed for an altered pattern of susceptibility to a compatible race of P. infestans and to potato virus X. Results indicate that constitutive expression of the STH-2 gene did not reduce susceptibility of potato to these pathogens.

Cloning, Molecular↗
PubMed1992

The R1 gene conferring race-specific resistance to Phytophthora infestans in potato is located on potato chromosome V.

Late blight in potato is caused by the fungus Phytophthora infestans and can inflict severe damage on the potato crop. Resistance to P. infestans is either based on major dominant R genes conferring vertical, race-specific resistance or on "minor" genes inducing horizontal, unspecific resistance. A dihaploid potato line was identified which carried the R1 gene, conferring vertical resistance to all P. infestans races, with the exception of those homozygous for the recessive virulence allele of the locus V1. The F1 progeny of a cross between this resistant parent P(R1) and P(r), a line susceptible to all races, was analysed for segregation of R1 and of restriction fragment length polymorphism (RFLP) markers distributed on the potato RFLP map comprising more than 300 loci. The R1 locus was mapped to chromosome V in the interval between RFLP markers GP21 and GP179. The map position of R1 was found to be very similar to the one of Rx2, a dominant locus inducing extreme resistance to potato virus X.

Chromosomes↗
PubMed1979

Multiple forms of soluble monophenol, dihydroxyphenylalanine: oxygen oxidoreductase (EC 1.14.18.1) from potato tubers (Solanum tuberosum). III. Influence of pH on the molecular weight distribution of enzyme activity in potato juice.

Gel chromatography on Sepharose and on Sephadex was used to separate the soluble phenol oxidase in various potato juices into multiple molecular forms ranging from 36,000 to 800,000 daltons. Adjustment of potato juice from physiological pH (ca. 6) to pH 4.5 or to pH 7.8 resulted in the predominance of low-mol.-wt. (less than 150,000 daltons) or high-mol.-wt. (greater than 150,000 daltons) enzyme forms, respectively. This suggests association phenomena of subunits. In potato juice of physiological pH and in potato juice adjusted to pH 4.5, all enzyme forms exhibited both monophenol and o-diphenol oxidase activities (assayed at pH 6.0). In potato juice adjusted to pH 7.8 considerable loss of monophenol oxidase activity (assayed at pH 6.0) occurred. This suggests that o-diphenol oxidase is more alkali-stable than monophenol oxidase. The significance of these findings for enzyme purifications and for the in vivo action of the enzyme is discussed.

Catechol Oxidase↗
PubMed2005

Nuclear and chloroplast DNA reassessment of the origin of Indian potato varieties and its implications for the origin of the early European potato.

The modern cultivated potato was first recorded in Europe in 1562, but its area(s) of exportation has long been in dispute. Two competing hypotheses have proposed an "Andean" area (somewhere from upland Venezuela to northern Argentina) or a lowland south central "Chilean" area. Potato landraces from these two areas can be distinguished, although sometimes with difficulty, by (1) cytoplasmic sterility factors, (2) morphological traits, (3) daylength adaptation, (4) microsatellite markers, and (5) co-evolved chloroplast (cp) and mitochondria (mt) DNA. The Chilean introduction hypothesis originally was proposed because of similarities among Chilean landraces and modern "European" cultivars with respect to traits 2 and 3. Alternatively, the Andean introduction hypothesis suggests that (1) traits 2 and 3 of European potato evolved rapidly, in parallel, from Andean landraces to a Chilean type through selection following import to Europe, and (2) the worldwide late blight epidemics beginning in 1845 in the United Kingdom displaced most existing European cultivars and the potato was subsequently improved by importations of Chilean landraces. We reassess these two competing hypotheses with nuclear microsatellite and cpDNA analyses of (1) 32 Indian cultivars, some of which are thought to preserve putatively remnant populations of Andean landraces, (2) 12 Andean landraces, and (3) five Chilean landraces. Our microsatellite results cluster all Indian cultivars, including putatively remnant Andean landrace populations, with the Chilean landraces, and none with the "old Andigenum" landraces. Some of these Indian landraces, however, lack the cpDNA typical of Chilean landraces and advanced cultivars, indicating they likely are hybrids of Andean landraces with Chilean clones or more advanced cultivars. These results lead us to reexamine the hypothesis that early introductions of potato to Europe were solely from the Andes.

Cluster Analysis↗
PubMed2002

Texture of cooked potatoes (Solanum tuberosum). 2. Changes in pectin composition during storage of potatoes.

During the storage season changes in the chemical composition of the pectin moiety of the cell walls of raw potatoes were studied. This compositional analysis was performed for the cultivars Nicola and Irene, which represent two extremes with regard to sensory-perceived texture. Both cultivars were divided into three size categories. From each size category a dry matter (DM) distribution was made. From these distributions potatoes at the low and high ends of this distribution were selected for further analysis. In total 12 different samples were analyzed three times during the storage season. The analysis comprised a pectin fractionation study. Pectic fractions were extracted from the cell wall material (CWM) by increasing the harshness of the extraction procedure. This resulted in a calcium-complexed pectic fraction, two pectic fractions weakly bound to the CWM, and a residue fraction, respectively. It was shown that no statistically significant differences (p > or = 0.95), either in yield or in chemical composition, could be observed between the two cultivars studied (Nicola and Irene), between sizes (large, medium, and small), and between potatoes with either high or low DM contents. However, statistically significant effects of storage both on the yield and on the chemical composition of the pectic moiety of the CWM could be observed, irrespective of cultivar, size, and DM content. Despite the substantial changes in the composition of the pectic moiety of the CWM of the raw material, no to minimal changes in the sensory-perceived texture of the cooked potatoes were observed upon storage. This suggests that the observed changes in pectin composition upon storage are overruled by other aspects that contribute more importantly to the sensory-perceived texture of steam-cooked potatoes.

Cell Wall↗
PubMed1997

Transgenic potato expressing a double-stranded RNA-specific ribonuclease is resistant to potato spindle tuber viroid.

We have produced transgenic potato lines expressing the yeast-derived double-stranded RNA-specific ribonuclease pac1. Five lines of pac1 potato (Solanum tuberosum L., cultivar Russet Burbank) challenged with potato spindle tuber viroid (PSTVd) suppressed PSTVd infection and accumulation. All of the progeny potato tubers produced by resistant plants were also free of PSTVd. Because the pac1 gene product digested PSTVd in vitro, double-stranded regions in PSTVd molecule and/or replicative intermediates may be targeted by pac1 gene product in the transgenic potato plant.

Endoribonucleases↗
PubMed2001

A major quantitative trait locus for resistance to Potato leafroll virus is located in a resistance hotspot on potato chromosome XI and is tightly linked to N-gene-like markers.

Potato leafroll virus (PLRV) causes one of the most widespread and important virus diseases in potato. Resistance to PLRV is controlled by genetic factors that limit plant infection by viruliferous aphids or virus multiplication and accumulation. Quantitative trait locus (QTL) analysis of resistance to virus accumulation revealed one major and two minor QTL. The major QTL, PLRV.1, mapped to potato chromosome XI in a resistance hotspot containing several genes for qualitative and quantitative resistance to viruses and other potato pathogens. This QTL explained between 50 and 60% of the phenotypic variance. The two minor QTL mapped to chromosomes V and VI. Genes with sequence similarity to the tobacco N gene for resistance to Tobacco mosaic virus were tightly linked to PLRV.1. The cDNA sequence of an N-like gene was used to develop the sequence characterized amplified region (SCAR) marker N127(1164) that can assist in the selection of potatoes with resistance to PLRV.

Chromosome Mapping↗
PubMed2002

Potato gene Y-1 is an N gene homolog that confers cell death upon infection with potato virus Y.

ADG2 is a DNA sequence mapped to a resistance (R) gene-rich region at the distal end of chromosome XI in potato (Solanum tuberosum subsp. andigena). The gene, in which ADG2 represents the predicted nucleotide-binding domain (NBS), was cloned and characterized. The coding region of the gene (designated as Y-1) is 6,187 bp long and structurally similar to gene N that confers hypersensitive resistance to Tobacco mosaic virus in Nicotiana spp. Both belong to the TIR-NBS-LRR class of genes and show 57% identity at the amino acid sequence level. The introns of Y-1 were spliced as predicted from the sequence. Y-1 cosegregated with Ry(adg), a gene for extreme resistance to Potato virus Y (PVY) on chromosome XI, as tested in a potato-mapping population and with independent potato cultivars. Leaves of the transgenic potato plants expressing Y-1 under the control of Cauliflower mosaic virus 35S promoter developed necrotic lesions upon infection with PVY, but no significant resistance was observed, and plants were systemically infected with PVY.

Amino Acid Sequence↗
PubMed2002

Volatiles from potato plants infected with potato leafroll virus attract and arrest the virus vector, Myzus persicae (Homoptera: Aphididae).

The influence of viral disease symptoms on the behaviour of virus vectors has implications for disease epidemiology. Here we show that previously reported preferential colonization of potatoes infected by potato leafroll virus (genus Polerovirus) (luteovirus) (PLRV) by alatae of Myzus persicae, the principal aphid vector of PLRV, is influenced by volatile emissions from PLRV-infected plants. First, in our bioassays both differential immigration and emigration were involved in preferential colonization by aphids of PLRV-infected plants. Second, M. persicae apterae aggregated preferentially, on screening above leaflets of PLRV-infected potatoes as compared with leaflets from uninfected plants, or from plants infected with potato virus X (PVX) or potato virus Y (PVY). Third, the aphids aggregated preferentially on screening over leaflet models treated with volatiles collected from PLRV-infected plants as compared with those collected from uninfected plants. The specific cues eliciting the aphid responses were not determined, but differences between headspace volatiles of infected and uninfected plants suggest possible ones.

Animals↗
PubMed1993

Functionally Homologous Host Components Recognize Potato Virus X in Gomphrena globosa and Potato.

All known isolates of potato virus X (PVX), with the exception of a South American isolate PVXHB, induce an extreme resistance response on potato carrying the Rx gene and elicit the production of necrotic lesions on Gomphrena globosa: PVXHB establishes systemic infection on Rx genotypes of potato and infects the inoculated leaf of G. globosa without lesion formation. Previously, we have shown that the Rx-mediated resistance is affected by a feature of the coat protein that depends on the presence of a threonine residue at position 121 in the coat protein of PVXCP4 and that the resistance is an induced response expressed in protoplasts of potato with the Rx genotype. In this study, we provide evidence, based on the analysis of PVXCP4/PVXHB hybrids, that the elicitation of lesions on G. globosa also requires the presence of a threonine residue at position 121 of the viral coat protein. The lesion-forming phenotype was not associated with the ability of the viral isolate to accumulate in the infected plant. We therefore propose that there is a homologous component of both potato carrying Rx and G. globosa that interacts with a feature of the PVX coat protein and, following the interaction, activates an induced response in the plant cell.

Journal Article↗
PubMed2005

Study on potato virus M (PVM) occurrence in potato fields in Iran.

57 native potato tuber samples collected from different potato growing region of Iran, planted on single rows in Karaj College experimental station. Plant samples of each single row plus 9.25 Fresh foliage samples collected from fields under new introduced cultivars were tested for potato virus (PVM) infection during growing season. Also 78 weeds and field crops belonging to Solonacae and Leguminosae from or neighboring to potato field were tested. Results indicated that PVM was not found on any plant other than potatoes. PVM was detected on 16 samples of 57 old vars, Virus was not seen in any samples collected from fields under new varieties. Results show that PVM is limiting in this crop. PVM detecting is difficult using assay hosts. Best test plants were French bean var Red kidney, Showing pinpoint necrotic LL, also Datura metel and Nicotiana debneyi are useful for virus detection showing chlorotic local lesion. Also microprecipition and gel diffusion test can be used for virus detection but Elisa was the best method. PVM infected plant showed 11-19.5 percent yield decrease in 3 cultivars tested.

Incidence↗
PubMed1980

Structural basis for the difference of the regulatory properties between potato and rabbit muscle phosphrylases. The NH2-terminal sequence of the potato enzyme.

alpha-Glucan phosphorylases (EC 2.4.1.1) from potato tuber and rabbit muscle are similar in some of the structural and kinetic properties, despite the difference in the regulation of enzyme activity. The NH2-terminal region in the rabbit muscle enzyme is important for both allosteric and covalent controls. In this paper, the NH2-terminal 104-residue sequence of the potato enzyme was determined to compare it with that of the rabbit muscle enzyme. Edman degradations of the whole protein revealed the terminal sequence of Thr-Leu-X-Glu-X-X-His-His-. Using this sequence as a marker, the NH2-terminal 81-residue peptide was isolated from the CNBr-treated protein and sequenced. The sequence of this peptide was extended further by the 23-residue sequence of the other two CNBr peptides by considering the sequence similarity between the potato and rabbit muscle enzymes. The combined results of the present and previous studies (Nakano, K., Wakabayashi, S., Hase, T., Matsubara, H. and Fukui, T. (1978) J. Biochem. (Tokyo) 83, 1085-1094 and Nakano, K., Fukui, T., and Matsubara, H. (1980) J. Biochem. (Tokyo) 87, 919-927) indicate that the potato and rabbit muscle enzymes are highly homologous except for the NH2-terminal 33-residue region which is very different. The potato enzyme has 2 more residues attached to the NH2-terminal region. The remarkable dissimilarity in the structure of this region provides a basis for the difference of the regulatory properties between the two enzymes. It is conceivable that phosphorylases existed originally as a large catalytically active molecule, and that the regulatory mechanism was then formed within the molecule during the course of evolution.

Amino Acid Sequence↗
PubMed1998

Fine structural changes in the ileum of mice fed on delta-endotoxin-treated potatoes and transgenic potatoes.

The present work has been designed to study the effect of feeding on transgenic potatoes, which carry the CryI gene of Bacillus thuringiensis var. kurstaki strain HD1, on the light and electron microscopic structure of the mice ileum, in comparison with feeding on potatoes treated with the 'delta-endotoxin' isolated from the same bacterial strain. The microscopic architecture of the enterocytes of the ileum of both groups of mice revealed certain common features such as the appearance of mitochondria with signs of degeneration and disrupted short microvilli at the luminal surface. However, in the group of mice fed on the 'delta-endotoxin', several villi appeared with an abnormally large number of enterocytes (151.8 in control group versus 197 and 155.8 in endotoxin and transgenic-treated groups, respectively). Fifty percent of these cells were hypertrophied and multinucleated. The mean area of enterocyte was significantly increased (105.3 microm(2) in control group versus 165.4 microm(2) and 116.5 microm(2) in endotoxin and transgenic-treated groups, respectively). Several forms of secondary lysosomes or auotophagic vacuoles were recognized in these cells. These changes were confirmed with the scanning electron microscope which revealed a remarkable increase in the topographic contour of enterocytes (23 microm in control group versus 44 microm and 28 microm in endotoxin and transgenic-treated groups, respectively) at the divulged surface of the villi. The basal lamina along the base of the enterocytes was damaged at several foci. Several disrupted microvilli appeared in association with variable-shaped cytoplasmic fragments. Some of these fragments contained endoplasmic reticulum, as well as ring-shaped annulate lamellae. In addition, the Paneth cells were highly activated and contained a large number of secretory granules. These changes may suggest that delta-endotoxin-treated potatoes resulted in the development of hyperplastic cells in the mice ileum. Although mild changes are reported in the structural configuration of the ileum of mice fed on transgenic potatoes, nevertheless, thorough tests of these new types of genetically engineered crops must be made to avoid the risks before marketing.

Animals↗