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1.
Two varieties of potato were treated with 14C- or 36Cl-radiolabelled chlorpropham to suppress sprouting, and stored under controlled ventilation conditions in the laboratory for up to 6 months at 10°C. The migration of chlorpropham into the potato tubers was studied at intervals by autoradiography and analysis of tuber extracts. Little penetration of chlorpropham beyond the peel layer occurred even after storage for 6 months. No identifiable degradation product of chlorpropham was detected in the extracts, although there was evidence of bound non-extractable residues. Volatile compounds lost by ventilation through the storage containers were collected in cold traps and analysed by liquid scintillation counting. Loss of chlorpropham by volatilisation from the tuber surface was very small.  相似文献   

2.
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3.
At concentrations near 2 × 10?4M, barban, chlorpropham, and phenmedipham are inhibitors of the electron transfer in potato and mung bean mitochondria. The inhibition seems to be localized in the flavoprotein region. It affects preferentially the exogenous NADH dehydrogenation, in potato mitochondria (I50, 10?4M). Succinate dehydrogenation is less inhibited. At noninhibiting concentrations, the studied carbamates cannot uncouple the oxidative phosphorylations. Photosynthesis is completely inhibited by 2.10?7M phenmedipham, 5 × 10?5M barban, and 2 × 10?4M chlorpropham. The inhibition takes place at the PS II level. Moreover, barban and chlorpropham are uncouplers of the photophosphorylations for concentrations between 5 × 10?5 and 5 × 10?4M. The effects observed on mitochondrial respiration can also be found on respiration of Acer cultured cells. The effects on isolated chloroplast photosynthesis are also observed for slightly higher concentrations on cultured Chlorella and on pea and oat leaf fragments.  相似文献   

4.
Dickeya and Pectobacterium are responsible for causing blackleg of plants and soft rot of tubers in storage and in the field, giving rise to losses in seed potato production. In an attempt to improve potato health, biocontrol activity of known and putative antagonists was screened using in vitro and in planta assays, followed by analysis of their persistence at various storage temperatures. Most antagonists had low survival on potato tuber surfaces at 4 °C. The population dynamics of the best low-temperature tolerant strain and also the most efficient antagonist, Serratia plymuthica A30, along with Dickeya solani as target pathogen, was studied with TaqMan real-time PCR throughout the storage period. Tubers of three potato cultivars were treated in the autumn with the antagonist and then inoculated with D. solani. Although the cell densities of both strains decreased during the storage period in inoculated tubers, the pathogen population was always lower in the presence of the antagonist. The treated tubers were planted in the field the following growing season to evaluate the efficiency of the bacterial antagonist for controlling disease incidence. The potato endophyte S. plymuthica A30 protected potato plants by reducing blackleg development on average by 58.5% and transmission to tuber progeny as latent infection by 47–75%. These results suggest that treatment of potato tubers with biocontrol agents after harvest can reduce the severity of soft rot disease during storage and affect the transmission of soft rot bacteria from mother tubers to progeny tubers during field cultivation.  相似文献   

5.
Potato virus Y (PVY) is responsible for major viral diseases in most potato seed areas. It is transmitted by aphids in a non-persistent manner, and it is spread in potato fields by the winged aphids flying from an infected source plant to a healthy one. Six different PVY strains groups affect potato crops: PVYC, PVYN, PVYO, PVYN:O, PVYNTN, and PVYN-Wi. Nowadays, PVYNTN and PVYN-Wi are the predominant strains in Europe and the USA. After the infection of the leaf and accumulation of the virus, the virus is translocated to the progeny tubers. It is known that PVYN is better translocated than PVYO, but little is known about the translocation of the other PVY strains. The translocation of PVY occurs faster in young plants than in old plants; this mature plant resistance is generally explained by a restriction of the cell-to-cell movement of the virus in the leaves. The mother tuber may play an important role in explaining mature plant resistance. PVY is able to pass from one stem to the other stems of the same plant through the vascular system of the mother tuber, but it is unknown whether this vascular link between stems is permanent during the whole life of the plant. Two greenhouse trials were set up to study the spread of PVY in the vascular system of the potato plant. The PVY-susceptible cultivar Charlotte was used for both trials. It was demonstrated that all stems growing from a PVY-infected tuber will become infected sooner or later, and that PVYN-Wi translocates more efficiently to progeny tubers than PVYNTN. It was also demonstrated that the progressive decay of the mother tuber in the soil reduces the possibility for virus particles to infect healthy stems through the vascular system of the mother tuber. This new element contributes to a better understanding of the mechanism of mature plant resistance.  相似文献   

6.
Differences in virulence between Fusarium sulphureum and Fusarium sambucinum were compared. Changes in reactive oxygen species production and metabolism in inoculated slices of potato tubers were also compared. The result showed that Fusarium infection induced significant production of ROS, lipid peroxidation and loss of cell membrane integrity, but low activity of superoxide dismutase (SOD) and ascorbate peroxidase (APX). Compared to F. sambucinum, F. sulphureum led larger lesion diameters on potato tubers and slices. It resulted in more superoxide anion (O2-) and earlier peak of hydrogen peroxide (H2O2), but lower activity of catalase (CAT) and APX, and accompanied with higher malondialdehyde (MDA) content and lower cell membrane integrity. These findings suggested that overproduction of ROS involved in the pathogenicity of Fusarium in potato tubers.  相似文献   

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8.
sec-Butylamine at 5 mM inhibited the oxidation of pyruvate by mitochondria isolated from hyphae of Penicillium digitalum, but had little effect on the oxidation of citrate, isocitrate, succinate, malate, acetyl-coenzyme A, or reduced nicotinamide adenine dinucleotide. sec-Butylamine did not interfere with oxidative phosphorylation, as evidenced by similar PO ratios in treated and control mitochondria. The pyruvate dehydrogenase complex (EC 1.2.4.1) isolated from young hyphae of P. digitatum was inhibited strongly by 20 mM sec-butylamine, whereas other tricarboxylic acid cycle enzymes were only slightly affected at most. Inhibition of the pyruvate dehydrogenase complex by sec-butylamine was competitive with respect to pyruvate. The Ki for sec-butylamine in the reaction was 1.38 × 10?2M, and the Km for pyruvate was 2.28 × 10?4M. These observations and other evidence derived from studies with intact hyphae support the hypothesis that the pyruvate dehydrogenase complex is the primary site of the fungistatic action of sec-butylamine.  相似文献   

9.
The root lesion nematode Pratylenchus penetrans parasitizes a wide range of economically important crops, including potato (Solanum tuberosum). Damage by P. penetrans impacts not only the potato yield but can also reduce the tuber quality. Detailed information on tuber infection by P. penetrans is scarce for most cultivars and molecular detection of nematodes from infected tubers is needed. The objective of this study was to assess tuber symptomatology due to P. penetrans infection in 10 potato cultivars and to provide an accurate molecular methodology for nematode detection using tuber peels. Sprouts of certified potato seed from cultivars Agata, Agria, Camel, Désirée, Dirosso, Kennebec, Laura, Picasso, Royata, and Stemster were planted in 2 L pots, and soil was inoculated with 4 P. penetrans/g of soil. Sixty days after inoculation, tubers were harvested, inspected for lesions, and the number of nematodes/g of potato peel assessed. Observations of tubers with symptoms showed the presence of P. penetrans in superficial layers of peels around the lenticels and injured necrotic tissue. Different nematode stages were detected in tubers of all inoculated cultivars, varying from 4 to 46 nematodes/g of potato peel. Species-specific primers showed suitable sensitivity and reproducibility for the detection of P. penetrans in tuber potato peel samples. The molecular detection of P. penetrans directly from tuber peels can facilitate routine nematode inspections of potato seed tubers or cull potatoes for nematode detection, and prevent further dissemination of this species.  相似文献   

10.
Potato tubers (cv. Alpha) were harvested at various time intervals after planting, or removed from storage at various times after harvest, and inoculated with different sporangial concentrations of three metalaxyl-sensitive (MS) and three metalaxyl-resistant (MR) isolates ofPhytophthora infestans. Disease parameters recorded were: (a) percentage of infected tubers; (b) percentage of blighted tuber surface area; and (c) depth of lesions. Blight was negatively correlated with tuber age both in the field and in storage. Susceptibility of tubers declined with age in the field but increased temporarily in storage.MR isolates did not differ significantly from MS isolates in percent of infected tubers but produced significantly larger and deeper lesions in tubers. Whereas inoculum concentration had a significant effect on the percent of infected tubers and of infected tuber surface area, it did not affect significantly the depth of the lesions. The results indicate that the MR isolates tested are stronger tuber blighters than the MS isolates.  相似文献   

11.
Potato tubers piled in storage are prone to infection by numerous pathogens. Each pathogen can cause damage alone, but severe losses often arise when more than one pathogen is involved. Currently, only a visual diagnosis is practiced on potato tubers before storing them, which does not allow any prediction of further disease spread. The aim of the present study was to determine differences in patterns of tissue colonization by several tuber decay pathogens and how late blight infection affects further tuber colonization by other important tuber pathogens. This study was conducted using artificial inoculation of potato tubers and PCR to provide an early and accurate diagnosis of disease development for major potato tuber rots, and to assess potential synergism/antagonism between Phytophthora infestans and other pathogens in stored tubers. In order to accurately follow the progress of each pathogen in tuber tissues, samples were collected over time from both the surface (peel, 0–2 mm depth) and internal tissues (flesh, depth > 2 mm) of the tubers at various distances from the inoculation site, at 3, 5, 7, 10, 12, 14, 17, and 19 days after inoculation. Successful detection of single or multiple pathogens was achieved using specific PCR-primers for each pathogen. Pathogens were always detected several centimeters ahead of the visible lesions. This tracking enabled us to determine the extent of colonization both on the tuber’s surface and in internal tissues by each tested pathogen, either after single or multiple infections involving P. infestans as the primary pathogen. The presence of P. infestans was shown to enhance the development of Pectobacterium atrosepticum and to slow down that of P. erythrospetica and Pythium ultimum. No noticeable effect on further tuber colonization by F. sambucinum, V. dahliae or V. albo-atrum was observed in the presence of P. infestans. This approach involving more than one pathogen is more realistic than classical studies considering single pathogens, and may be helpful in monitoring the sanitary status of stored tubers. Our results make the outcome of certain combinations of pathogens in potato tubers more predictable and may result in more efficient preventive measures.  相似文献   

12.
D M JOEL 《Weed Research》2007,47(4):276-279
Parasitic plants of the Orobanchaceae are known as obligate root parasites that develop haustoria that connect to roots of various host plants. This article describes, for the first time, a case where the root parasite successfully connected to potato tubers, i.e. to the swollen portion of an underground stem rather than to a root. The rhizosphere of Orobanche aegyptiaca and of its host Solanum tuberosum (potato) was carefully examined. In anatomical studies, the adventitious roots were directly connected to potato tubers. Numerous secondary haustoria, which developed along the adventitious roots in close vicinity to the potato tuber, penetrated the tuber epidermis and the perimedullary tuber parenchyma and developed xylem strands that are presumably connected to the minor xylem strands within the tuber cortex. These findings indicate that parasites of the Orobanchaceae that normally attack host roots may also parasitise underground stem tubers.  相似文献   

13.
In field trials performed by the Institute for Plant Protection of the Bavarian State Research Center for Agriculture (LfL) in Freising in 2001 and 2002, it was studied, whether Clavibacter michiganensis ssp. sepedonicus (Cms), the bacterial ring rot pathogen of potato, could be transmitted to seed potatoes by the use of contaminated crates. Healthy seed tubers were brought into contact with Cms before planting by (i) storage in freshly contaminated crates at 8°C for 4 weeks, (ii) storage at unregulated cellar temperature (between 1 and 15°C) for 8 months in crates, which were already contaminated and empty at filling time for 5 months and (iii) storage in freshly contaminated crates at 4°C for 5 months. Infections of stems and tubers of the plants were determined by polymerase chain reaction (PCR) and indirect immunofluorescence antibody staining (IFAS). Storage of healthy tubers in contaminated crates produced infected plants in all three treatments: PCR results of the tubers were positive in 2 (ii) to 9% (i) of the plants.  相似文献   

14.
Formation of the nitroso derivatives of 14C-labeled carbaryl, carbofuran, and p-chlorophenyl methylcarbamate (PCMC), and their subsequent stabilities were investigated using low levels of carbamate (0.5 μmol) and aqueous HCl concentrations encompassing those considered maximum for the gastric contents of humans (pH 1–2) and of rats (pH 3–4). Reacting the carbamates with excess sodium nitrite for 10 min at 37°C in a pH 1.0 HCl solution gave nitrosocarbamate yields of 42 to 64%, while only trace amounts were formed at pH 2 and above. The nitrosocarbamates were most stable at pH 3–5 with half-lives ranging from 114 to 470 min. Stability of all three nitroso derivatives was considerably less at pH 1.5 (t12, 25–34 min), but at pH 7 the stability varied: nitroso-PCMC t12, 6 min; nitrosocarbofuran t12, 70 min; nitrosocarbaryl t12, 139 min. Denitrosation to the parent carbamate was the predominant degradation pathway at pH 1.5, but at pH 3–7 degradation was primarily by hydrolysis of the carbamate ester linkage. Each of the nitrosocarbamates was directly mutagenic in the S. typhimurium assay system. Since the data show that nitrosation of residue levels of carbamate pesticides occurs readily at pH 1 but not at pH 2 and above, it is critical that gastric contents of any animal model used for assessing nitrosocarbamate formation have a pH approaching 1 as may occur in the human stomach.  相似文献   

15.
Potato (Solanum tuberosum) is the largest crop in Israel. Production is based on the import of seed tubers from Europe for the spring crop. Imported tubers are generally free from virus infection. The most important virus infecting potato is Potato virus Y (PVY), which may cause severe damage to marketable yields. In Israel, tubers from the spring harvest are stored over the summer for planting in the autumn. It is important to be able to determine the infection rate of seed tuber lots from the spring harvest prior to storage. Commonly, infection is measured by sprouting tubers and measuring virus titre in the leaves using ELISA (the “Growing-On test”), which takes at least 6 weeks to give results. There is a need for a faster method to produce results, such as Taqman Real Time PCR (qPCR), for direct analysis of viral infection in tubers at harvest. To use qPCR as a diagnostic tool, it is necessary to demonstrate that both techniques give comparable results on batches of field-grown tubers. Such a comparison was performed on potential seed tuber lots of 14 different cultivars over three Israeli spring harvests (2013–2015). The agreement between the results of the two techniques was not of high statistical significance. However, the qPCR technique can distinguish well, by binary classification, between tuber lots with a low PVY infection rate (<5% by Growing On test; suitable for seed) and those unsuitable for seed (≥5% by Growing On test). Therefore, qPCR is an appropriate technique for determination of the PVY infection rate of seed tuber lots in Israel.  相似文献   

16.
The method currently used for testing potato tubers for viruses following harvest involves a growing‐on test. This takes up to 6 weeks to complete, and there is therefore a demand for more rapid test results. The sensitivity and reliability of direct tuber testing by DAS‐ELISA and real‐time RT‐PCR (TaqMan) were compared with the growing‐on test. In addition, the reliability of all three methods for the detection of Potato Y potyvirus (PVY) in tubers was compared over post‐harvest intervals of 6, 10, 14 and 18 weeks. The test material came from plots of tubers (cv. ‘Maris Piper’) containing a primary infection of strains PVYN and PVYO, following aphid transmission from marked infector plants grown during the 2003 season. Sample material was homogenized and divided, to provide comparative test material for detection of PVY by ELISA and real‐time RT‐PCR. Tuber eye‐plugs were then taken and subjected to the growing‐on test. The remainder of the tuber was also grown on and tested, to ensure infection was not missed as a consequence of an uneven distribution of virus throughout the tuber material. The results obtained using the two methods for direct testing of the tubers, and those results obtained from the traditional growing‐on test, are compared. The advantages and disadvantages of each method are discussed.  相似文献   

17.
Pectate lyase (PL) enzymes are major virulence factors of Erwinia carotovora (Ec) bacteria. They degrade plant cell wall pectin into unsaturated oligogalacturonates (OG) known to elicit plant defence responses. Therefore, a gene encoding the isoenzyme PL3 of Ec ssp. atroseptica was transformed by means of Agrobacterium into potatoes of cv. Désirée. Four PL-transgenic potato plant lines selected on the basis of greenhouse experiments were grown over a period of 4 years (1997–2000) in the field. It is shown that the heterologous PL enzyme mediated an enhanced resistance to Erwinia soft rot in field grown tubers. Thus compared to the non-transgenic counterpart extension of rotting was significantly reduced (P < 0.001) on the wound surface of PL-expressing tubers. Moreover, the threshold density ofEc -bacteria causing a progressive soft rot was up to 19-fold higher on tuber tissue containing the PL enzyme. An induction of plant defence responses in PL-transgenic potatoes may be indicated by an enhanced resistance of tuber tissue cell walls to Erwinia -derived enzymes, an increased PPO- and PAL-activity in tuber tissue as well as by a strengthened formation of necrosis on the wound surface of tubers after infection with Ec -bacteria.  相似文献   

18.
The goal of this research was to identify quantitative trait loci (QTLs) for potato tuber resistance to the soil- and seedborne bacterium Dickeya solani and for tuber starch content, to study the relationship between these traits. A resistant diploid hybrid of potato, DG 00-270, was crossed with a susceptible hybrid, DG 08-305, to generate the F1 mapping population. Tubers that were wound-inoculated with bacteria were evaluated for disease severity, expressed as the mean weight of rotted tubers, and disease incidence, measured as the proportion of rotten tubers. Diversity array technology (DArTseq) was used for genetic map construction and QTL analysis. The most prominent QTLs for disease severity and incidence were identified in overlapping regions on potato chromosome IV and explained 22.4% and 22.9% of the phenotypic variance, respectively. The second QTL for disease severity was mapped to chromosome II and explained 16.5% of the variance. QTLs for starch content were detected on chromosomes III, V, VI, VII, VIII, IX, XI, and XII in regions different from the QTLs for soft rot resistance. Two strong and reproducible QTLs for resistance to D. solani on potato chromosomes IV and II might be useful for further study of candidate genes and marker development in potato breeding programmes. The relationship between tuber resistance to bacteria and the starch content in potato tubers was not confirmed by QTL mapping, which makes the selection of genotypes highly resistant to soft rot with a desirable starch content feasible.  相似文献   

19.
Streptomyces scabies, causative agent of common scab of potato, produces the phytotoxins concanamycin and thaxtomin. In a potato tuber slice assay to study the contribution of concanamycins to lesion development, concanamycin A had weak necrosis-inducing activities; >10× the amount of thaxtomin A was needed to produce equivalent lesion severity. Concanamycins were detected in tubers inoculated with S. scabies, which caused deep-pitted lesions but not in those inoculated with Streptomyces acidiscabies, which caused corky, raised lesions. In field-grown, diseased potatoes, concanamycin content tended to be higher in tubers with deep-pitted lesions than in those with corky, raised lesions.  相似文献   

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