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1.
A. Rivera-Peña 《Potato Research》1990,33(4):469-478
Summary Development of plants ofSolanum demissum (dms) andSolanum verrucosum was followed in three sites at altitudes of 2950, 3250 and 3500 m, and the incidence of late blight and physiological races
determined. No plants were found that had grown from true seed although berry formation was abundant indms.
Tubers sprouted during the dry period and most shoots emerged at the beginning of the rainy season in late April. Emergence
continued for about two months indms, and new plants were later formed from stolons, so that plants of different ages were present at the same time. Late blight
was first found in cultivated fields adjacent to the site at 2950 m, and three weeks later lesions were found in wildSolanum species (WSS) simultaneously at all sites. Few plants per colony of WSS were infected and none was seriously damaged. Complex
races (6–10 virulence genes) were found early in the season at one locality. 相似文献
2.
A. Rivera-Peña 《Potato Research》1990,33(4):479-486
Summary Plants of wildSolanum species (S. demissum (dms), S. verrucosum (ver), S. iopetalum (iop), S. brachycarpum (bra), and an unidentified species (unsp), from the natural habitat were inoculated in the laboratory withPhytophthora infestans race 0, to see if major genes for resistance were present, and with the most complex and aggressive race available in an
attempt to reveal the level of general resistance.
No plant with a susceptible reaction to race 0 was found in 120 plants ofdms, and 34 plants ofunsp. Plants with a hypersensitive reaction to race 0 and susceptible plants were found inver. When infected with a complex aggressive isolate of the fungus 73.5% of the WSS plants were susceptible. It was concluded
that WSS in the area possess both complex race specific resistance and a high level of general resistance, whose effects cannot
yet be separated. 相似文献
3.
Summary During the period 1982–87, wildSolanum species were surveyed in an area of 15000 ha by observations and collections along five long (10 km) transects covering altitudes
from 2900 to 3900 m, and twelve short (300 m) transects. The sevenSolanum species,demissum (dms), verrucosum (ver), iopetalum, brachycarpum, x edinense, stoloniferum and an unidentified species, possibly a sterile hybrid betweendms andver, grew patchily and their many small colonies formed part of a complex plant community that changed in composition with altitude
and topography. The most frequent species wasdms (80%), while other species often grew in mixed colonies with it. As the altitude increased, so did the distances between
colonies, whereas species diversity decreased and above 3500 m onlydms was found. Most species propagated both clonally, through tubers on long stolons, and sexually through botanical seed. 相似文献
4.
A. Rivera-Peña 《Potato Research》1990,33(3):349-355
Summary A survey of races ofPhytophthora infestans was made in 1985 and 1986 on the western slopes of the volcano Nevado de Toluca, Mexico. Isolates were collected from infected
plants of wildSolanum species found in five long (7–10 km) and some short (300–500 m) transects. The study are of 15 000 ha was between 2900 and
3900 m altitude. Isolates were collected fromSolanum demissum (35 isolates),verrucosum (11),iopetalum (2),brachycarpum (7),stoloniferum (2), r-genotype (9) and from differential hosts (11).
No isolate was identified as race 0. Ten virulence genes were identified with a set of differential hosts and the most common
were numbers 2 and 4. Isolates with eight virulence genes were the most common and those with ten were found on eight occasions
in the natural habitat and on three in the experimental fields. 相似文献
5.
Summary In this paper we present observations made during three years in a potato field in Sweden that indicated the presence of soil
borne inoculum ofPhytophthora infestans. In 1994, a fungicide trial against late blight was left in the field with various degrees of late blight infection. In 1995,
cereals was grown in the field. In 1996, certified potato seed tubers were planted and blight appeared early in the season
in a pattern corresponding to the heavily infected areas in 1994. No volunteer potato plants were found in 1995 or 1996. Both
mating types A1 and A2 were isolated in 1996 and 1997 and oospores were found in leaves, stems as well as in stolons. 相似文献
6.
Claudia Tonon Adriana Andreu Maria Elvira Aued Marcela Van Damme M. Huarte G. R. Daleo 《Potato Research》1998,41(4):319-325
Summary The kinetics of accumulation of chitinases, glucanases and phytoalexins were studied in two potato cultivars, differing in
their degrees of vertical and horizontal resistance, when infected with two races ofPhytophthora infestans. Tuber disks of cvs Kennebec (susceptible, low horizontal resistance) and Huinkul (tolerant, high horizontal resistance)
were infected with either race “0” (avirulent) or “C” (complex, race 1.3.5.7.11) ofPhytophthora infestans. Extracts of tuber tissue (0–7 days) from cv. Kennebec infected with race “0” showed a strong increase in phytoalexin production
and in chitinase and glucanase activities when compared with those infected with race “C”. These results indicate that race
“C” is able to block defensive reactions. No significant differences were observed in cv. Huinkul infected with both races.
The contribution of these reactions to horizontal resistance is unknown, and our results would not support a conclusive role
for them in the interaction. 相似文献
7.
Summary Potato late blight has appeared in epidemic proportions in Nepal since the mid 1990s and fungicides have been reported to
be decreasingly effective in managing the disease.Phytophthora infestans isolates were collected from potato crops during 1999–2000 and analysis of 371 isolates for mating types and 270 isolates
for metalaxyl sensitivity revealed the presence of both new and old populations. This is the first report on the presence
of metalaxyl-resistant isolates in Nepal. The frequencies of A1 and A2 were 83 and 17%, respectively. Metalaxyl-resistant,
intermediate and sensitive isolates were recorded as 10%, 12% and 78% respectively. Metalaxyl resistance was distributed in
both mating types. Sites with a history of metalaxyl use had a significantly higher number of resistant and intermediate isolates
({ie337-1}, P<0.01) than sites where metalaxyl had not been used. This study confirms the changes in population structure
ofP. infestans in Nepal. 相似文献
8.
Summary Phenylamide-based fungicides were reintroduced to the Irish market in 1985. Mixtures of phenylamides and mancozeb were recommended
for no more than 3 sprays in potato late blight control programmes with the last systemic spray to be applied not later than
31 July. Samples of potato foliage infected withP. infestans were collected from the main potato growing areas in Ireland over a five-year period starting in 1985. Using the floating
disc method, 11% of the crops sampled in 1985 were found to have phenylamide-resistant strains ofP. infestans present. The number of crops with resistant strains increased rapidly up to 1988 when 83% of the crops sampled had resistance.
Factors affecting the distribution of resistance and the efficacy of a phenylamide-based spray programme are discussed. 相似文献
9.
Summary Potato tubers were inoculated with two biotypes ofPhytophthora infestans then stored at 3,7, 10 and 15°C. Image analysis quantified average reflective intensity (ARI) of diseased tissue from cut
surfaces of sample tubers. Tuber tissue infection and infection rate were measured by calculating Mean ARI of samples. Average
tuber tissue infection and infection rate was minimal at 3°C (P.i.-US8 orP.i.-US1). Tuber tissue infection increased at temperatures >3°C, from 220 Mean ARI seven days after inoculation (dai) to 190–150
Mean ARI 50 dai (depending on cultivar and biotype ofP. infestans). Rate of tuber tissue infection caused byP.i.-US1 at 7°C was about zero in cv. Snowden but greater than −0.2 ARI day−1 (cvs Russet Burbank and Superior). Rate of late blight infection in tuber tissue generally increased with temperature from
−0.2 ARI day−1 (at 7°C) in all cultivars to a maximum of −0.8 ARI day−1 (10°C). 相似文献
10.
Summary The severity of late blight tuber rot in five potato cultivars (Green Mountain, Sebago, Dorita, AC Brador and Island Sunshine)
resulting from inoculation with US-1/US-8 combinations of Canadian isolates ofPhytophthora infestans was evaluated. In addition, the potential for mixed (A1∶A2) inoculations to result in oospore formation was examined. In
studies conducted in 1996 and 1997, cv. Dorita (and Island Sunshine in 1997) developed the least amount of surface or internal
necrosis relative to the other cultivars following co-inoculation with US-1 and US-8 isolates ofP. infestans. Differences also were revealed among isolate combinations used for inoculation. The combination of a US-1 isolate from Prince
Edward Island with a US-8 isolate from New Brunswick consistently produced the least amount of necrosis in tubers of the various
cultivars. There was no evidence of oospore production in any of the tubers examined.
AAFC Contribution No. 919 相似文献
11.
Summary One hundred and four isolates ofPhytophthora infestans were collected during 1990–93 from different potato growing regions of India. They were paired with mating type A1 ofP. capsici to determine their mating type. All isolates from the Indo-Gangetic plains and Assam were the A1 mating type, whereas a mixed
population of A1 and A2 types occurred at Shillong, Darjeeling and Shimla hills. The frequency of A2 isolates was 5–30% in
the Shimla hills and 60% and 58% respectively in the Shillong and Darjeeling hills. 相似文献
12.
C. Cerato L. M. Manici S. Borgatti R. Alicchio R. Ghedini A. Ghinelli 《Potato Research》1993,36(4):341-351
Summary Cells of seven potato cultivars were selectedin vitro with culture filtrate (CF) ofPhytophthora infestans (Mont.) de Bary. Regenerated plants were tested for late blight resistance. The aim of the study was to check the efficacy
of CF in the selection of potatoes for resistance to late blight and to evaluate the effects of additive factors on general
resistance. One selection cycle, applied to a cell culture system, selected cells resistant to toxic metabolites of CF.In vivo screening of clones regenerated from selected cells was done in two steps: on whole plants, assessing foliage late blight,
and on detached leaves, assessing single factors of horizontal resistance.
In general, the frequency of resistant variants selected with CF did not differ from that of resistant somaclonal variants.
Nevertheless, high concentrations of CF in the growth medium seemed to induce an improvement of some partial resistance factors
as compared with the source plants. 相似文献
13.
Summary Neotuberosum clones with differing levels of resistance toFusarium coeruleum andFurarium sulphureum, and putative resistance toPhytophthora infestans, were selected and used in crosses with Tuberosum clones. The resulting progenies were assessed for their resistance to each
of these pathogens and for breeders' preference. There was little correlation between disease scores for the twoFusarium species (r=0.21 and 0.34 for the Neotuberosum and hybrid clones respectively), indicating that resistance to each species
is distinct. Statistical analyses revealed differences between the Neotuberosum parents and between the Tuberosum parents
for all traits, but the Neotuberosum differences for late blight were not significant (P=0.10–0.05) when tested against the
interaction between the two sets of parents. The interaction was significant forF. coeruleum and breeders' preference, but notF. sulphureum. No reciprocal differences were found. The only statistically significant correlation between traits for the 72 progenies
was a small one (r=0.33; P=0.01–0.001) between the twoFusarium species; for all other pairs of traits r was less than 0.10.
It is concluded that there are good prospects for combinding resistances to the twoFusarium species from different sources and also for achieving high levels of other desirable characteristics. 相似文献
14.
Summary A total of 251Phytophthora infestans isolates collected during 1999–2000 potato growing seasons from nine potato growing areas of Nepal were tested for virulence
using a set of eleven potato differentials. The virulence test revealed the presence of 30 races with the most frequent being
4.11, 4 and 11. Twenty-nine percent of isolates belonged to simple races having none to one virulence factor, whereas 71%
had complex virulence factors governed by 2 to 7 genes. Gleason and Shannon indices of 5.24 and 2.59, respectively, showed
a moderate level of diversity in NepaleseP. infestans populations. Shannon indices comparison among regional populations revealed significant differences (t-test, P<0.001) in
the diversity. The population from hills were the most diverse followed byterai and the high hill populations. The virulence complexities were minimal in Nepalese populations. The implications of these
findings in association with the potato cultivation system in Nepal are discussed. 相似文献
15.
Summary
Phytophthora infestans isolates collected in Poland in 1987–1995 were evaluated on detached leaflets of a differential series consisting of potato
genotypes possessing resistance genes R1–R11. On the same differentials was evaluated over three years a highly virulentP. infestans isolate MP 245.
Isolate MP 245 and those from natural populations ofP. infestans were seldom or inconsistently pathogenic to R5, R8 and R9. When leaflets of the differentials were infected with MP 245 the
lesions were often small and sporulation weak. A statistically significant interaction was found between years and pathogenicity
of MP 245 to individual differentials. Attempts to train the isolate MP 245 for pathogenicity to R9 were unsuccessful.
The variation in specific resistance of potato genotypes may complicate the evaluation of their resistance toP. infestans, as well as the evaluation of the virulence spectrum of natural fungus populations. This variation may be due to changes
in specific pathogenicity of the fungus or in specific resistance of the potato. Some differentials have a possibly useful
resistance toP. infestans. 相似文献
16.
Zusammenfassung Ergebnisse systematischer Prüfung auf relative Resistenz der Knollen von 1274 Herkünften der ssp.andigena (adg) genenüberPhytophthora infestans werden mitgeteilt. Die Methode des Kn?llchenstestes erm?glichte dabei das Eindringen des Pilzes direkt ins Knollenmark oder
über die intakte Schale. Nur etwa 1% der Herkünfte enthielt einen Anteil von >25% Idiotypen mit gutem Resistenzniveau. Eine
Analyse der Fundorte ergab keine Anhaltspunkte für die gezielte Suche von Resistenzquellen. Ergebnisse aus der züchterischen
Nutzung von adg betreffen die ph?notypische Resistenz der Nachkommen und weitere Merkmale.
Summary Results are reported of late blight resistance inS. tuberosum ssp.andigena (adg) and its use in breeding. Tests were carried out on material of the gene bank in Gross Lüsewitz (GLKS). Seedlings were cultivated under glass cover in a 6-years test period. To examine tuber resistance toPhytophthora infestans the following test was set up: 2–5 tubers per idiotype, up to 8 idiotypes per accession and year of test were taken and 1274 different accessions were examined with an average number of 23 idiotypes and 59 tubers from each. Inoculation was made by fresh deep cuts to the pith and by subsequent immersion in a solution of zoospores, 6–9×104 ml−1 with a mixture of the pathotypes (1.2.3.4.5.7.10.11, 1.2.3.4.7.8.10 and 1.2.3.4) at a temperature of 16–18°C and at an air humidity of >90%. Evaluation of the presence of aerial mycelium and browning after 7 days allowed the calculation of a resistance score (BK): grade 9 (highly resistant) to grade 1 (highly susceptible). The mean values derived from the accessions (Fig. 1) revealed that a medium level of susceptibility is dominating and that they rarely exceed average levels of cultivars. Approximately 1% of the accessions contained ≥25% of idiotypes with BK ≥6 and these may be interesting for breeding purposes. Table 1 shows the analysis of accessions with the most favourable mean values. Geographic evaluation did not yield indications for a more purposeful search for sources of resistance, since detailed reports on find-spots were missing (Table 2). Combination tests withPhytophthora-resistant genes of adg for crosses of adg withS. demissum (dms) andS. stoloniferum (sto) proved to be more useful as they partly showed good heritable resistance to haulm and tuber infection ofP. infestans (Table 3). The problem of the possible role of unknown r-genes is discussed. Only a few crosses with ssp.tuberosum (tbr) generated a progeny with sufficient resistance. Selection from such progeny over several years resulted after the second year in rejections, mainly because of susceptibility for viruses, too small tubers and lack of flowering (Table 4). Results of varietal research of the former German Democratic Republic proved that with the use of suitable parents in breeding for nematode resistance,Phytophthora susceptibility from adg could be balanced off (Table 5). The cultivar Auralia is a good example of the importance of adg in achieving a high level of resistance to late blight.相似文献
17.
U. Darsow 《Potato Research》2004,47(3-4):175-185
Summary During assessment of tuber blight resistance using three test methods, the sites of entry ofPhytophthora infestans into the tuber was estimated for 41 cultivars. The trials were conducted using a mix of three highly virulent isolates at
Gro? Lüsewitz 1991–1993. The influence of date of harvest and intermediate storage before inoculation was examined with two
cultivars in 1993. Two levels of soil moisture and five densities of inoculum were tested in 1994. Methods of assessment of
tuber blight resistance, cultivars, years and all their interactions showed a significant effect on sites of entry. Eye infections
identified the highest the level of resistance and correlated best with tuber blight resistance in net bag test, r=-0.58.
Soil moisture and temperature before harvest varied the ontogenic development of resistance and the relation of sites of entry
of the pathogen from July to September. Intermediate storage changed the resistance and the preferred site of cultivar-specific
infection. Interactions cultivar x soil moisture and cultivar x density of inoculum were significant and should be considered
in the resistance assessment of cultivars. 相似文献
18.
D. Andrivon 《Potato Research》1994,37(3):279-286
Summary Nineteen races were found among 116 isolates ofPhytophthora infestans recovered from French potato and tomato crops during 1991–1993. The most common races were 1.3.4.7.11. 1.3.4.7.8.11 and 1.3.4.7.10.11
in 1991, race 1.3.4.7.11 in 1992, and race 1.3.4.7.10.11 in 1993. None of the isolates was virulent to either R2 or R6, and
only one to R5. The mean number of virulences per isolate was 5.78 in 1991, 4.35 in 1992 and 4.53 in 1993. TheP. infestans population from Brittany showed mainly quantitative changes in the frequencies of major races over the period investigated,
but races identified were almost the same in all 3 years. No geographical substructure was apparent, since variation between
locations accounted for only 13–22% of the total racial diversity within the Brittany population. This is interpretated as
evidence for limited gene flow in this population, which is believed to have evolved from a few founding genotypes. 相似文献
19.
Summary The effect of up to 19 essential oils (EOs) isolated from different types of plant species against potato late blight,Phytophthora infestans has been studied in vitro and under greenhouse conditions. Two isolates ofP. infestans were in a first screening exposed to an inhibition test using the EOs in a standard plate assay measuring the diameter of
the development fungal zone. Representative oils selected from this first screening were then applied to susceptible potato
plants and both the fungicidal and phytotoxic effects were examined. While most of the EOs tested in the fungus plate assay
showed no desirable inhibitory action against the pathogen, four of the EOs produced an inhibition zone of 80%. EOs from thyme
had e.g. an 89% inhibitory effect on the fungus isolates, but did not display protection in the potato study, and in addition
caused phytotoxic symptoms. On the other hand, treatment with hyssop in the plate assay demonstrated only up to 45% of inhibition,
but hyssop promoted good fungus protection for the plants and stimulated the plant growth without any signs of phytotoxity. 相似文献
20.
Summary Laboratory experiments and observations in commercial stores showed that viable sporangia ofPhytophthora infestans can be produced on infected potato tubers of different cultivars. Infection was also found to spread from diseased to healthy
tubers during handling. 相似文献