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1.
R.A. Browne B.M. Cooke 《European journal of plant pathology / European Foundation for Plant Pathology》2004,110(1):91-102
An in vitro detached leaf assay, involving the inoculation of detached leaves with Microdochium nivale, was further developed and used to compare with whole plant resistance ratings to Fusarium head blight (FHB) of 22 commercial cultivars and published information on 21 wheat genotypes, identified as potential sources for FHB resistance. An incubation temperature of 10 °C and isolates of M. nivale var. majus of intermediate pathogenicity were found to be the most suitable for the differential expression of several components of partial disease resistance (PDR), namely incubation period, latent period and lesion length, in wheat genotypes used in the detached leaf assay. There were highly significant differences (P < 0.001) for each component of PDR within commercial cultivars and CIMMYT genotypes. Positive correlations were found between incubation period and latent period (r = 0.606; P < 0.001 and r = 0.498; P < 0.001, respectively, for commercial cultivars and CIMMYT genotypes), inverse correlations between incubation period and lesion length (r = -0.466; P < 0.01 and r = –0.685; P < 0.001, respectively) and latent period and lesion length (r = –0.825; P < 0.001 and r = –0.848; P < 0.001, respectively). Spearman rank correlations between individual PDR components and UK 2003 recommended list ratings were significant for incubation period (rs = 0.53; P < 0.05) and latent period (rs = 0.70; P < 0.01) but not for lesion length (r
s = –0.26). Commercial cultivars identified with high resistances across all three PDR components in the detached leaf assay also had high whole plant FHB resistance ratings, with the exception of cv. Tanker which is more susceptible than the results of the detached leaf assay suggested, indicating an additional susceptibility factor could be present. Agreement between resistances found in the detached leaf assay and resistance to FHB suggests resistances detected in detached leaves are under the same genetic control as much of the resistances expressed in the wheat head of the commercial cultivars evaluated. In contrast, high resistances in each of the PDR components were associated with higher susceptibility across 19 CIMMYT genotypes previously evaluated as potential breeding sources of FHB resistance (incubation period: r = 0.52; P < 0.01, latent period: r = 0.53; P < 0.01, lesion length: r = –0.49; P < 0.01). In particular, the CIMMYT genotypes E2 and E12 together with Summai #3, known to have high levels of whole plant FHB resistance, showed low levels of resistance in each PDR component in the detached leaf assay. Such whole plant resistances, which are highly effective and not detected by the detached leaf assay, do not appear to be present in Irish and UK commercial cultivars. The most resistant Irish and UK commercial cultivars were comparable to the genotype Frontana and the most resistant CIMMYT germplasm evaluated in the leaf assay. 相似文献
2.
R.A. Browne B.M. Cooke 《European journal of plant pathology / European Foundation for Plant Pathology》2004,110(1):87-90
A technique to improve the sporulation of Microdochium nivale in culture and to produce mycelium-free conidial suspensions was evaluated using cellophane-covered potato dextrose agar (PDA). Time to sporulation was significantly shorter on the cellophane-covered PDA (P < 0.001), yields of conidia were higher (P < 0.01) and conidial suspensions were produced virtually free of the mycelial fragments present in suspensions from PDA only. The conidial inoculum produced on cellophane had lower pathogenicity to wheat cv. Equinox in a detached leaf assay, showing significantly longer incubation periods (P < 0.05) and latent periods (P < 0.01), than conidia produced on PDA alone. However, the apparent decline in pathogenicity of conidial suspensions produced on cellophane compared to PDA alone was small. 相似文献
3.
P. Nicholson A.S. Turner S.G. Edwards G.L. Bateman L.W. Morgan D.W. Parry J. Marshall M. Nuttall 《European journal of plant pathology / European Foundation for Plant Pathology》2002,108(2):163-177
The progress of development of stem-base pathogens in crops of second winter wheat was plotted in nine experiments in three years. The amount of each pathogen present was determined by quantitative PCR. Where Tapesia yallundae was present in quantifiable amounts, it usually developed earlier than the other eyespot pathogen, T. acuformis. Both species were usually present in greater amounts on cultivars which are more susceptible to eyespot. The sharp eyespot pathogen, Rhizoctonia cerealis, developed more erratically than either of the Tapesia spp. and there were no consistent effects on different cultivars. Fusarium spp., the cause of brown foot rot, were rarely present in quantifiable amounts, but Microdochium nivale was usually present as one or both of the varieties nivale and majus. Late-season (after anthesis) decreases in M. nivale suggest that any brown foot rot symptoms attributable to this fungus would have fully developed earlier. Cultivar differences in amounts of M. nivale were most clear in stems during internode extension and when relatively large amounts of DNA were present. Such differences approximately reflected eyespot susceptibility, cv. Soissons containing most and cv. Lynx containing least DNA. The results emphasise the difficulty in relating diagnoses, by quantitative PCR or other means, at early growth stages when decisions to apply fungicides against stem-base disease are made, to later disease severity. 相似文献
4.
Blanca Fontaniella Carlos Vicente Roberto de Armas María Estrella Legaz 《European journal of plant pathology / European Foundation for Plant Pathology》2007,119(4):401-409
Polyamine and phenolic acid levels as well as activities of some enzymes of their biosynthetic metabolism were examined in
two sugarcane (Saccharum officinarum) cultivars differing in susceptibility to leaf scald, a disease caused by the bacterium, Xanthomonas albilineans. Juice obtained from both infected cultivars showed significantly increased levels of free putrescine and ornithine decarboxylase
activity. However, the pathogen induced different changes in the two cultivars in subsequent metabolic steps. Whereas acid
insoluble conjugated spermidine completely disappeared from the highly susceptible cv. C 439-52, an increase in acid insoluble
conjugated polyamines was observed in the moderately susceptible cv. L 55-5. Phenolic acid metabolism also differed in the
two cultivars. Since total phenolic acid content and phenylalanine ammonium lyase activity was greater in both cultivars after
infection, distribution of phenolic acids between free or conjugated forms diverted into different pathways. The level of
susceptibility of the two cultivars is discussed in terms of changes in these compounds. 相似文献
5.
Polymnia P. Antoniou Emmanouil A. Markakis Sotirios E. Tjamos Epaminondas J. Paplomatas Eleftherios C. Tjamos 《European journal of plant pathology / European Foundation for Plant Pathology》2008,122(4):549-560
An innovative inoculation process, involving the drilling of a trunk hole in 3 year-old olive trees and injecting a dense
conidial suspension of Verticillium dahliae, was developed to study differentiation in foliar symptom expression between olive cultivars tolerant or susceptible to the
pathogen. It was demonstrated that V. dahliae conidia could be translocated and colonize the xylem at the same distance above and below the point of trunk injection in
both cultivars. However, the pathogen could be subsequently isolated at statistically significant percentages in susceptible
cv. Amphissis compared to the tolerant cv. Kalamon, indicating operation of resistance mechanisms in the vascular phase of
the disease. Consequently symptom development in the susceptible cultivar was at least sixfold more intensive compared to
the tolerant cultivar, 6–11 months after trunk inoculation. Perennial olive orchard experiments, aimed at selecting Verticillium-resistant
root-stocks, were conducted by applying the novel method in 2–3 year-old root-stock suckers of Amphissis olive trees and in
the tolerant cvs Lianolia of Corfu and Koroneiki. It was indicated that potentially resistant root-stocks could be obtained
following the trunk drilling technique. Resistance differentiation between cvs Amphissis and Kalamon was further verified
through root inoculation by various V. dahliae microsclerotial concentrations and demonstrated that the trunk drilling inoculation procedure is equally efficient in resistance
evaluation of olives to Verticillium wilt. The trunk inoculation procedure could be useful in selecting and screening root-stocks
for resistance to V. dahliae and other vascular pathogens and could elucidate resistance mechanisms in woody plants against vascular wilt diseases. 相似文献
6.
S. Šliková V. Šudyová P. Martinek I. Polišenská E. Gregová D. Mihálik 《European journal of plant pathology / European Foundation for Plant Pathology》2009,124(1):163-170
Determination of the Fusarium protein equivalent (FPE) levels in kernels for better characterisation of genotypes showing Fusarium head blight (FHB) resistance, and better detection of susceptibility to kernel infection among genotypes with slight symptom
expression was carried out. Twelve wheat cultivars and eight hexaploid winter wheat lines derived from a cross of Triticum aestivum with related species T. macha, T. polonicum, and T. dicoccoides were evaluated for levels of spike and kernel infection, the content of the mycotoxin deoxynivalenol (DON) and FPE in kernels
after artificial inoculation with the fungus Fusarium culmorum in the field in 2006–2007. The ELISA immunochemical method was employed for the quantitative analyses of DON and FPE. Three
wheat lines had a significantly low infection of spikes and kernels compared to cvs Sumai 3 and Nobeoka Bozu, indicating the
presence of specific resistance mechanisms to FHB. The significantly low AUDPC (area under the disease progress curve) and the high level of FPE and DON content in kernels
indicated a lack of resistance in one wheat line (crossed with T. polonicum). The results showed highly significant correlations (P < 0.01) between FPE and DON content and between FPE and AUDPC. In addition, correlations between FPE and reductions in yield
components were also highly significant. Quantification of Fusarium spp. in wheat kernels can be helpful for evaluating wheat genotypes for their levels of resistance to FHB. 相似文献
7.
Leena Tripathi John Odipio Jaindra Nath Tripathi Geoffrey Tusiime 《European journal of plant pathology / European Foundation for Plant Pathology》2008,121(1):9-19
The banana Xanthomonas wilt disease (BXW) has threatened the livelihood of millions of farmers in East Africa. Use of resistant varieties is the
most cost-effective method of managing this bacterial disease. A reliable and rapid screening method is needed to select resistant
banana varieties. An in vitro screening method was developed for early evaluation of Xanthomonas wilt resistance using small tissue culture-grown plantlets. Eight cultivars of banana were screened with sixteen isolates
of Xanthomonas campestris pv. musacearum using this method. There were significant differences (P < 0.0001) in susceptibility among the various banana cultivars tested, whereas no significant difference (P = 0.92) in pathogenicity was observed between the pathogen isolates. The cv. Pisang Awak (Kayinja) was found to be highly
susceptible and Musa balbisiana resistant. Nakitembe was found to be moderately resistant while cvs Mpologoma, Mbwazirume, Sukali Ndiizi, FHIA-17 and FHIA-25
were susceptible. The susceptibility of these cultivars was further tested in vivo by artificial inoculation of potted plants
with similar results. This study shows that an in vitro screening test can serve as a convenient, cheap and rapid screening
technique to discriminate BXW-resistant from BXW-susceptible banana cultivars. 相似文献
8.
Cora Boedo Valérie Le Clerc Mathilde Briard Philippe Simoneau Michel Chevalier Sonia Georgeault Pascal Poupard 《European journal of plant pathology / European Foundation for Plant Pathology》2008,121(1):55-66
The interaction between Alternaria dauci and two carrot cultivars differing in their resistance to leaf blight was investigated by microscopy. The fungal development
between 1 and 15 days post-inoculation was quite similar in the susceptible cv. Presto and the partially resistant cv. Texto:
After conidial germination, leaf adhesion of the pathogen was achieved with mucilaginous filaments; hyphae penetrated the
leaves directly with/without the formation of appressoria-like structures or via stomata; the fungus spread by epiphytic hyphae with hyphopodia and subcuticular mycelia. Intense necrotic plant cell reactions
occurred under the fungal structures. At 21 days post-inoculation, typical features of fungal development were noted for each
cultivar: growing hyphae emerged from stomata in cv. Presto, whereas conidiophores without conidia were observed in cv. Texto.
Leaf tissues of both cultivars were strongly damaged and vesicle-like structures (assumed to be plant phenolics) were abundantly
present between mesophyll cells. A real-time PCR method was developed for in planta quantification of A. dauci. Between 1 and 15 days post-inoculation, the fungal biomass was equivalent in the two cultivars and was about fourfold higher
in cv. Presto than cv. Texto at 21 and 25 days post-inoculation. Taken together, our results indicated that A. dauci was able to colonize both cultivars in a similar manner during the first steps of the interaction, then fungal development
in the partially resistant cultivar was restricted due to putative plant defence reactions. The results of this study enhance
the overall understanding of infection processes in the A. dauci-carrot pathosystem. 相似文献
9.
Interactions between Barley yellow dwarf virus (BYDV) and Fusarium species causing Fusarium head blight (FHB) in winter wheat cvs Agent (susceptible to FHB) and Petrus (moderately resistant
to FHB) were studied over three years (2001–2003) in outdoor pot experiments. FHB developed more rapidly in cv. Agent than
in cv. Petrus. The spread of FHB was greater in BYDV-infected plants than in BYDV-free plants. Thousand grain weight (TGW)
was reduced more in Fusarium-infected heads of cv. Agent than in cv. Petrus. A highly significant negative correlation was found between disease index
and TGW in cv. Agent (r = −0.916), while in cv. Petrus the correlation was less significant (r = −0.765). Virus infection reduced TGW in cv. Petrus more than in cv. Agent. In plants with both infections, TGW reductions
in cv. Petrus corresponded to those of BYDV infection, and in cv. Agent TGW was more diminished than in BYDV infection. Effects
of different treatments determined over three years on ergosterol contents in grain were generally similar to effects on disease
indices. Grain weight per ear and ear weight of the different treatments of both cultivars largely corresponded with the TGW
results. Deoxynivalenol (DON) content in grain of cv. Agent infected with Fusarium spp. was 11–25 times higher compared to the corresponding treatments in cv. Petrus. The DON content in grain of plants of
the two cultivars infected with both pathogens was higher than that of plants infected only with Fusarium over the three years. 相似文献
10.
J.M. Brennan B. Fagan A. van Maanen B.M. Cooke F.M. Doohan 《European journal of plant pathology / European Foundation for Plant Pathology》2003,109(6):577-587
The effect of temperature on the in vitro growth rates and pathogenicity of a European Fusarium collection consisting of isolates of Fusarium graminearum,
F. culmorum,
F. avenaceum, F. poae and Microdochium nivale was examined. Irrespective of geographic origin, the optimum temperature for the growth of F. graminearum, F. culmorum and F. poae was 25 °C, while that for F. avenaceum and M. nivale was 20 °C. In general, the growth rates of F. graminearum, F. culmorum and F. poae increased between 10 and 25 °C and those of F. avenaceum and M. nivale increased between 10 and 20 °C. Pathogenicity tests were carried out by examining the effect of the five species on the in vitro coleoptile growth rate of wheat seedlings (cv. Falstaff). Irrespective of geographic origin, the temperature at which F. avenaceum, F. culmorum and F. graminearum caused the greatest retardation in coleoptile growth ranges 20–25 °C (>89.3% reduction), whilst for F. poae and M. nivale it was 10–15 °C (>45.6% retardation), relative to uninoculated control seedlings. In general, F. culmorum and F. graminearum were the most pathogenic of the five species, causing at least a 69% reduction in coleoptile growth at 10, 15, 20 and 25 °C. General linear model analysis (GLIM) showed that species accounted for 51.3–63.4% of the variation in isolate growth and from 19.5% to 44.3% of the variation in in vitro pathogenicity. Country of origin contributed from 22.6% to 51.9% to growth rate variation and from 0.73% to 7.61% to pathogenicity variation. The only significant correlation between in vitro growth and pathogenicity was that observed for M. nivale at 15 °C (r = -0.803, P < 0.05). 相似文献
11.
Soledad Verdejo-Lucas F. Javier Sorribas 《European journal of plant pathology / European Foundation for Plant Pathology》2008,121(1):103-107
Nematode reproduction on the nematode-susceptible tomato cv. Durinta grafted onto the Mi-resistance gene tomato rootstock SC 6301 was compared to the Mi-resistance gene tomato cv. Monika in a plastic house infested with Meloidogyne javanica. The ungrafted susceptible cv. Durinta was included as a control for reference. Final soil population densities were lower
(P ≤ 0.05) on the resistant than susceptible cultivar but intermediate values were recorded on the rootstock SC 6301. The lowest
numbers of eggs per gram root were recorded on the resistant cultivar followed by those on the rootstock; in both cases, they
were lower (P < 0.05) than on the susceptible control. Cumulative yield (kilogram per square meter) was higher (P < 0.05) on the resistant than susceptible cultivar whether or not it had been grafted. The rootstock SC 6301 provided an
intermediate resistance response to M. javanica and was less effective than the resistant cultivar in suppressing nematode populations and plant damage under the experimental
conditions of this study. 相似文献
12.
The relative resistance of 15 winter barley, three winter wheat and three winter oat cultivars on the UK recommended list 2003 and two spring wheat cultivars on the Irish 2003 recommended list were evaluated using Microdochium nivale in detached leaf assays to further understand components of partial disease resistance (PDR) and Fusarium head blight (FHB) resistance across cereal species. Barley cultivars showed incubation periods comparable to, and latent periods longer than the most FHB resistant Irish and UK wheat cultivars evaluated. In addition, lesions on barley differed from those on wheat as they were not visibly chlorotic when placed over a light box until sporulation occurred, in contrast to wheat cultivars where chlorosis of the infected area occurred when lesions first developed. The pattern of delayed chlorosis of the infected leaf tissue and longer latent periods indicate that resistances are expressed in barley after the incubation period is observed, and that these temporarily arrest the development of mycelium and sporulation. Incubation periods were longer for oats compared to barley or wheat cultivars. However, oat cultivars differed from both wheat and barley in that mycelial growth was observed before obvious tissue damage was detected under macroscopic examination, indicating tolerance of infection rather than inhibition of pathogen development, and morphology of sporodochia differed, appearing less well developed and being much less abundant. Longer latent periods have previously been related to greater FHB resistance in wheat. The present results suggest the longer latent periods of barley and oat cultivars, than wheat, are likely to play a role in overall FHB resistance if under the same genetic control as PDR components expressed in the head. However the limited range of incubation and latent periods observed within barley and oat cultivars evaluated was in contrast with wheat where incubation and latent periods were shorter and more variable among genotypes. The significance of the various combinations of PDR components detected in the detached leaf assay as components of FHB resistance in each crop requires further investigation, particularly with regard to the apparent tolerance of infection in oats and necrosis in barley, after the incubation period is observed, associated with retardation of mycelial growth and sporulation. 相似文献
13.
Emmanouil A. Markakis Sotirios E. Tjamos Polymnia P. Antoniou Epaminondas J. Paplomatas Eleftherios C. Tjamos 《European journal of plant pathology / European Foundation for Plant Pathology》2009,124(4):603-611
Verticillium wilt is the most serious olive disease in the Mediterranean countries and worldwide. The most effective control
strategy is the use of resistant cultivars. However, limited information is available about the level and source of resistance
in most of the olive cultivars and there are no published data using microsclerotia, the resting structures of Verticillium dahliae, as the infective inoculum. In the present study, we correlated symptomatology and the presence of the fungus along with
the DNA relative amount (molecules μl−1) of a defoliating (D) and a non-defoliating (ND) V. dahliae strain in the susceptible cv. Amfissis and the tolerant cvs Kalamon and Koroneiki, as quantified by the Real-Time QPCR technology.
The viability of the pathogen in the plant tissues was confirmed by isolating the fungus on PDA plates, while symptom assessment
proved the correlation between the DNA relative amount of V. dahliae in plant tissues and cultivar susceptibility. It was further demonstrated that the D and ND strains were present at a significantly
higher level in cv. Amfissis than in cvs Kalamon and Koroneiki. It was finally observed that the relative amount of the pathogen
in roots was lower than in stems and shoots and declined in plant tissues over time. These data constitute a valuable contribution
in evaluating resistance of olive cultivars or olive root-stocks to V. dahliae pathotypes. 相似文献
14.
M. Szechyńska‐Hebda M. Hebda D. Mierzwiński P. Kuczyńska M. Mirek M. Wędzony A. van Lammeren S. Karpiński 《Plant pathology》2013,62(4):867-878
This study showed that several mechanisms of the basal resistance of winter triticale to Microdochium nivale are cultivar‐dependent and can be induced specifically during plant hardening. Experiments and microscopic observations were conducted on triticale cvs Hewo (able to develop resistance after cold treatment) and Magnat (susceptible to infection despite hardening). In cv. Hewo, cold hardening altered the physical and chemical properties of the leaf surface and prevented both adhesion of M. nivale hyphae to the leaves and direct penetration of the epidermis. Cold‐induced submicron‐ and micron‐scale roughness on the leaf epidermis resulted in superhydrophobicity, restricting fungal adhesion and growth, while the lower permeability and altered chemical composition of the host cell wall protected against tissue digestion by the fungus. The fungal strategy to access the nutrient resources of resistant hosts is the penetration of leaf tissues through stomata, followed by biotrophic intercellular growth of individual hyphae and the formation of haustoria‐like structures within mesophyll cells. In contrast, a destructive necrotrophic fungal lifestyle occurs in susceptible seedlings, despite cold hardening of the plants, with the host epidermis, mesophyll and vascular tissues being digested and becoming disorganized as a result of the low chemical and mechanical stability of the cell wall matrix. This work indicates that specific genetically encoded physical and mechanical properties of the cell wall and leaf tissues that depend on cold hardening are factors that can determine plant resistance against fungal diseases. 相似文献
15.
R. A. Browne C. Bequain F. Mascher 《European journal of plant pathology / European Foundation for Plant Pathology》2006,116(3):199-210
One hundred and nineteen entries from the CIMMYT International Wheat and Maize Improvement Centre 2004/05 Fusarium head blight (FHB) resistance screening nursery were evaluated as possible sources of novel components of partial disease resistance (PDR), against FHB and Microdochium nivale snow mould, detected using a detached leaf assay. In addition the FHB resistant cvs Arina, Alsen and Frontana and 21 European wheat genotypes were included for comparison. There was wide variation among CIMMYT entries for the PDR components incubation period, latent period and lesion length (P < 0.001) and European lines for incubation and latent periods (P < 0.001). The CIMMYT entries with the longest latent periods were not superior to cv. Arina, the best European source of this PDR component identified to date. Notably the CIMMYT lines exhibiting the longest latent periods had Aegilops
squarrosa (878) in their pedigree, indicating that Ae.
squarrosa (878) may be a source of enhanced resistance detected by latent period. Macroscopic observation suggested that the underlying mechanisms contributing to latent period may differ among the CIMMYT germplasm and European sources of long latent period such as cv. Arina. Among the CIMMYT germplasm, incubation period was only weakly correlated with latent period (r = 0.25; P < 0.01); this also was the case among European genotypes (r = 0.36; P < 0.05) supporting previous findings that these PDR components are largely under separate genetic control. However, the correlation was higher on a subset of the most resistant and susceptible lines for latent period (r = 0.73 and r = 0.44; incubated at 10 °C and 15 °C, respectively). While a number of the European lines had latent periods that were comparable to cv. Arina many were significantly shorter indicating potential for improvement in this PDR component. Adaptations to the experimental design utilized in the present experiments for the efficient evaluation of large numbers of genotypes utilizing the detached leaf assay are discussed. 相似文献
16.
I. Kiecana E. Mielniczuk Z. Kaczmarek M. Kostecki P. Golinski 《European journal of plant pathology / European Foundation for Plant Pathology》2002,108(3):245-251
Inoculation experiments with 14 genotypes of oats (10 cultivars and 4 lines) were performed during 1996, 1997 and 1998 in Sitaniec, South-Eastern Poland. Panicles of oats were inoculated with a conidial suspension of Fusarium avenaceum, which caused a reduction in yield by 33% and in 1000 kernel weight (TKW) by 21%. During the period between inoculation and harvest, F. avenaceum was able to accumulate moniliformin (MON) in kernels at an average level of 0.13mgkg–1 (gg–1). The highest reduction of yield components caused by the F. avenaceum inoculation was found for cv. Santor, followed by lines CHD 1171, STH 2795 and cvs: Kwant and Farys, while cvs Slawko, Dukat, Borys and Komes exhibited the highest resistance to the disease in terms of TKW and yield reductions after inoculation. 相似文献
17.
Á. Mesterházy T. Bartók G. Kászonyi M. Varga B. Tóth J. Varga 《European journal of plant pathology / European Foundation for Plant Pathology》2005,112(3):267-281
Different sets of wheat genotypes were tested under field conditions by spraying inocula of isolates of seven Fusarium spp. and Microdochium nivale (formerly F. nivale) in the period 1998–2002. The severity of Fusarium head blight (FHB), Fusarium-damaged kernels (FDK), the yield reduction and the deoxynivalenol (DON) contamination were also measured to describe the nature of the resistance. The degrees of FHB severity of genotypes to F. graminearum, F. culmorum, F. avenaceum, F. sporotrichioides, F. poae, F.␣verticillioides, F. sambucinum and M. nivale were very similar, indicating that the resistance to F.␣graminearum was similar to that for other Fusarium spp. listed. This is an important message to breeders as the resistance relates not only to any particular isolate of F. graminearum, but similarly to isolates of other Fusarium spp. This holds true for all the parameters measured. The DON contamination refers only to DON-producers F. graminearum and F. culmorum. Highly significant correlations were found between FHB, FDK, yield loss and DON contamination. Resistance components such as resistance to kernel infection, resistance to DON and tolerance were identified in the more susceptible genotypes. As compared with western European genotypes which produced up to 700 mg kg−1 DON, the Hungarian genotypes produced only 100 mg kg−1 at a similar FDK level. This research demonstrates the importance of measuring both FDK and DON in the breeding and selection of resistant germplasm and cultivars. 相似文献
18.
Marcondes Araújo da Silva Kamila Câmara Correia Maria Angélica Guimarães Barbosa Marcos Paz Saraiva Câmara David Gramaje Sami J. Michereff 《European journal of plant pathology / European Foundation for Plant Pathology》2017,147(3):695-708
Severe outbreaks of Alternaria leaf blotch and fruit spot were recently observed in cv. Pink Lady apples in northern Israel, especially on fruit. Such severe outbreaks have not been reported from other countries. Symptoms involved cracks and rot around the calyx and external rot of the fruit body. Up to 80 % of the fruit in some orchards were affected by the disease. Microscopic examinations, fulfillment of Koch’s postulates and molecular (genetic) analyses confirmed the causal agent as Alternaria alternata f. sp. mali. The incidence of Alternaria increased as the degree of calyx cracking increased, or if fruit were both cracked and rotted. Injecting spore suspensions into the fruit produced typical rot symptoms. Injection assays of detached fruit of eight apple cultivars showed that cvs. Pink Lady and Golden Delicious were susceptible whereas cv. Jonathan was resistant. Pink Lady and Golden Delicious produced more fruit rot as the inoculum concentration increased. Rot in all three cultivars was moderate close to the skin but more severe close to the seed locule. Aqueous extracts taken from Jonathan fruit peel inhibited germ tube elongation of A. alternata f. sp. mali in vitro. This is the first report on heavy infection of Pink Lady fruit in Israel caused by A. alternata f. sp. mali. 相似文献
19.
To determine whether populations of Phytophthora infestans attacking wild and cultivated potatoes in the highlands of Peru are specialized on their hosts of origin, we characterized
isolates using several neutral markers, metalaxyl resistance and for aggressiveness in a detached leaf assay. One hundred
and fifty-three isolates were collected from the northern and central highlands of Peru from different potato cultivars (both
modern and native cultivars) and from different species of wild, tuber-bearing potatoes. All the isolates analyzed belonged
to one of four clonal lineages that had been described previously in Peru: EC-1, US-1, PE-3 and PE-7. The EC-1 lineage (n = 133) was dominant and present in similar frequencies on wild and cultivated potatoes. PE-3 (n = 14) was found primarily on cultivated potatoes, with only one isolate coming from a wild host. US-1 (n = 2) and PE-7 (n = 4) were rare; all but one (PE-7) occurred on wild potatoes. Isolates from the EC-1 lineage from modern cultivars were compared
in three separate detached leaf inoculation assays with EC-1 isolates from the wild potato species S. sogarandinum, S. bill-hookerii or S. huancabambense, respectively. No significant interactions between isolate type (from wild or cultivated potato) and host type (wild or cultivated)
were measured for any assay. It appears that the pathogen genotypes in the EC-1 lineage indiscriminately attack both wild
and cultivated tuber-bearing solanaceous hosts in Peru, and breeders should be able to select for resistance using the common
EC-1 lineage. 相似文献
20.
Experiments were conducted to determine the effectiveness and profitability of the Mi-resistance gene in tomato in suppressing populations of Meloidogyne javanica in a plastic-house with a natural infestation of the nematode. Experiments were also conducted to test for virulence and durability of the resistance. Monika (Mi-gene resistant) and Durinta (susceptible) tomato cultivars were cropped for three consecutive seasons in non-fumigated or in soil fumigated with methyl bromide at 75 g m–2 and at a cost of 2.44 euros m–2. Nematode densities were determined at the beginning and end of each crop. Yield was assessed in eight plants per plot weekly for 6 weeks. The Pf/Pi values were 0.28 and 21.6 after three crops of resistant or susceptible cultivars, respectively. Growth of resistant as opposed to susceptible tomato cultivars in non-fumigated soil increased profits by 30,000 euros ha–1. The resistant Monika in non-fumigated soil yielded similarly (P > 0.05) to the susceptible Durinta in methyl bromide fumigated soil but the resistant tomato provided a benefit of 8800 euros ha–1 over the susceptible one because of the cost of fumigation. Selection for virulence did not occur, although the nematode population subjected to the resistant cultivar for three consecutive seasons produced four times more eggs than the population on the susceptible one. Such a difference was also shown when the resistant cultivar was subjected to high continuous inoculum pressure for 14 weeks. The Mi-resistance gene can be an effective and economic alternative to methyl bromide in plastic-houses infested with root-knot nematodes, but should be used in an integrated management context to preserve its durability and prevent the selection of virulent populations due to variability in isolate reproduction and environmental conditions. 相似文献