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1.
Pectolytic enzymes produced by Didymella bryoniae in a liquid medium containing pectin as sole carbon source and in inoculated etiolated hypocotyls of 10 melon cultivars, as well as those constitutively expressed in spores, were studied by isoelectric focusing, quantitatively and qualitatively. Five constitutive pectin lyase (PNL) isoenzymes differing in isoelectric joint (pI), one acidic (pI 3.9) and four basic (pI 8.4, 8.9, 9.3, 9.9) were expressed in extracts from spores. The same PNL isoenzyme pattern was detected in culture filtrates and in infected tissues of all the melon cultivars tested. Polygalacturonase (PG) activity, represented by a single inducible acidic band (pI 4.6) was detected only in culture filtrates. A single constitutive basic pectin methylesterase (PME) isoenzyme (pI > 10.0) was also found in spores, culture filtrates and inoculated melon tissues. All cultivars were susceptible at the seedling growth stage, but with differences in disease severity; cultivars Amarillo Oro and Juane Canari were, respectively, the least and most susceptible. Pectin lyase activity was highly correlated with disease severity. In rotted tissues and culture filtrates, an increase in pH to values over 7.0 was recorded, values optimal for PNL activity. In this plant–pathogen interaction, PNL activity represents the principal pectolytic component and these isoenzymes were associated with the onset of disease, disease severity and an increase in pH of infected tissue. 相似文献
2.
Variation of apoplastic pH by Fusarium culmorum and its influence on the production, activity and isoenzymes patterns of the pathogenesis‐related (PR) proteins β1,3‐glucanase, chitinase and peroxidase enzymes were detected in apoplastic fluids (AFs) from infected wheat seedlings. The time course in the 24–48 h interval post infection was characterized by an increase in activity and isoenzymatic differential induction of the selected PR proteins and by a concomitant rise of apoplastic pH. Chitinase attained maximum activity at pH 8·0 in the case of inoculated seedlings. Optimal β1,3‐glucanase activity in the pH range 6·0–8·0, was observed at pH 7·0. Peroxidase was strongly affected by pH, with enzyme activity having a maximum rate at pH 6·0 and thereafter rapidly declining at higher pH. Maximum peroxidase activity paralleled the appearance of the complete isoenzymatic pattern. In order to investigate the biological role of PR proteins in AFs, the in vitro antifungal activity was evaluated. In the interval 0–6 h, pH of macroconidia suspensions rose up to 7·2. AFs revealed inhibitory activity against germinating macroconidia of F. culmorum by decreasing the germination efficiency of macroconidia apical compartments, while this effect was compensated by an increased germination capacity of middle compartments. Present results suggest that during infection of wheat seedlings by F. culmorum the pH modulation favours host colonization by enhancing the activity of pectin lyase, and simultaneously inhibits the capacity of the host to oppose the pathogen by interfering with peroxidases which represent an important component of the defence arsenal. 相似文献
3.
J. Zhang B. D. Bruton C. L. Biles 《European journal of plant pathology / European Foundation for Plant Pathology》2014,139(4):749-761
Didymella bryoniae is an important pathogen of cucurbits worldwide. Virulence factors of D. bryoniae were investigated in regard to fungal growth and the production of the cell wall-degrading enzymes, polygalacturonase (PG), pectate lyase (PL), pectin lyase (PNL), β-galactosidase (β-Gal) and cellulase (Cx). Virulence levels of five D. bryoniae isolates were determined by the severity of inoculated cantaloupe fruit decay. The highly virulent isolates had more mycelial growth than the moderately virulent isolates in different media. PG activities produced by the highly virulent isolates in shake cultures and in decayed fruit were greater than those of the moderately virulent isolates. PNL, but not PL, in decayed fruit was higher with the highly virulent isolates compared to the moderately virulent ones. The highly virulent isolates showed higher Cx activity than the moderately virulent ones in decayed fruit and in fruit tissue shake culture. β-Gal activities of the highly virulent isolates in pectin shake culture and in decayed fruit were greater than those of the two moderately virulent isolates although fruit also produced β-Gal. Protein analysis showed two fungal β-Gal isozymes in decayed fruit compared to those of healthy fruit. Correlation analysis indicated that the activities of PG, PNL, β-Gal and Cx in cultures and in decayed fruit positively correlated with fungal growth and fruit decay severity. The results of this study suggest that PG, PNL, β-Gal, and Cx appear to be virulence factors of D. bryoniae in cantaloupe decay with PG and β-Gal as the most predominant fruit decay enzymes. 相似文献
4.
This study investigated the expression and characterization of two polygalacturonases (PG1 and PG2) of Fusarium graminearum during infection of wheat spikelets; after purification, these were demonstrated to be products of two unique endo - pg genes annotated in the genome database of F. graminearum . Both genes ( Fgpg1 and Fgpg2 ) were expressed in vitro and during spike infection. PG1 had a greater specific activity, with a maximum at pH 5–7, was largely secreted in liquid culture and clearly detectable in the infected ovary tissue. PG2 was more active at pH 7–7·8, was poorly secreted in liquid culture and faintly detectable in infected ovaries. Both PG-encoding genes were maximally expressed 24 h after wheat spikelet infection, paralleling the expression of a pectin lyase ( Fgpnl1 ) gene; they anticipated the expression of a xylanase gene ( FgxylA ) that was induced only 48 h after infection with a maximum at 96 h. These data strongly indicate F. graminearum -secreted PG activity at an early stage of wheat infection. 相似文献
5.
The effect of small temperature differentials (16 vs. 20°C) on the pathogenicity of deoxynivalenol producing single isolates of Fusarium culmorum and F. graminearum and on the fusarium head blight (FHB) response of eight wheat cultivars was examined. Fusarium culmorum inoculation caused greater visual disease symptoms at 20°C than at 16°C, both overall and on an individual cultivar basis (overall AUDPC = 13·5 and 9·6, respectively) ( P < 0·05). In contrast, F. graminearum inoculation caused greater overall visual disease symptoms at 16°C than at 20°C, both overall and at the individual cultivar level (overall AUDPC = 12·8 and 10·9, respectively) ( P < 0·05). Results showed both F. culmorum and F. graminearum inoculations caused a greater loss in yield at 20°C (54·3 and 46·9% relative 1000-grain weight, respectively) compared with 16°C (73·3 and 66·9% relative 1000-grain weight, respectively) ( P < 0·05). Fusarium culmorum -inoculated heads contained similar amounts of fungal DNA at both 16 and 20°C (1·9 and 1·7 ng mg−1 of plant material, respectively) (not significant), while for F. graminearum inoculation, plants contained higher amounts of fungal DNA at 20°C (2·0 and 1·0 ng mg−1 of plant material, respectively) ( P < 0·05). Overall, there was a significant negative correlation between AUDPC and percentage relative 1000-grain weight at both 16 and 20°C ( r =−0·693 and −0·794, respectively, P < 0·01). 相似文献
6.
The in vitro production of extracellular polygalacturonase, pectin lyase, and cellulase by hop isolates of Verticillium albo-atrum was studied. A total of 24 isolates belonging to the two pathotypes commonly described as fluctuating or progressive, according to the symptoms produced in certain susceptible hop cultivars, were grown in liquid shake cultures. The media used contained glucose, pectin or acetone-extracted hop tissue as a carbon source. The production of all three enzymes was significantly correlated with pathotype when the medium contained hop tissue. Pectin lyase production was also correlated with pathotype when pectin was used as the carbon source. The influence of carbon source on enzyme output and possible reasons for some exceptions to the correlations observed are discussed. 相似文献
7.
P. Marciano 《Phytoparasitica》1994,22(2):101-108
The polygalacturonase (PG) activity in culture filtrates fromSclerotinia sclerotiorum is reduced when glyceollin I, the major soybean phytoalexin, is present in the culture medium. When the enzyme activities
in the culture filtrates are expressed per unit of fungal growth, PG activity decreases with increasing concentration of glyceollin
I in the culture medium. The phytoalexin does not influence the isoenzyme pattern. This suggests that glyceollin I may inhibit
quantitative but not qualitative enzyme production. Only the highest glyceollin I concentration tested inhibits oxalic acid
production. The inhibitory effect on mycelial growth is confirmed. The data suggest a further hypothesis about the role of
phytoalexin during pathogenesis. 相似文献
8.
D. M. Elgersma 《European journal of plant pathology / European Foundation for Plant Pathology》1976,82(5):161-172
Polygalacturonase (PG) and cellulase (Cx) production byOphiostoma ulmi was determined in growth media of pH 3.0. 5.0 and 7.0 containing ethanol-extracted or freeze-dried elm wood. PG activity was low or absent in cultures of pH 7.0. Cx production was not affected by differences in pH. Production of PG was much higher with freeze-dried wood than with ethanol-extracted wood. No differences in PG and Cx activities were found between cultures with freeze-dried wood of resistant or of susceptible elms. No correlation was found between PG and Cx production and aggressiveness of strains ofO. ulmi. The decrease of PG activity during incubation with increasing pH, was not due to the formation of PG inhibitors. 相似文献
9.
番茄芝麻斑病原菌产生的细胞壁降解酶种类及其活性变化 总被引：3，自引：0，他引：3
番茄芝麻斑点病原菌能够产生一系列细胞壁降解酶,即果胶甲基酯酶(PE)、多聚半乳糖醛酸酶(PG)、果胶甲基半乳糖醛酸酶(PMG)、多聚半乳糖醛酸反式消除酶(PGTE)、果胶甲基反式消除酶(PMTE)和纤维素酶(Cx)。酶动力学研究表明:产生的各种细胞壁降解酶均有特定的最适反应条件。水解酶类的PG、PMG、Cx最大酶活的pH均为5.0,温度均为50℃;裂解酶类的PGTE和PMTE最大酶活的pH均为9.0,温度均为30℃,与其他病菌产生的细胞壁降解酶的特性基本相同。在活体外,随着培养天数的增加PG、PMG、PGTE、PMGE、Cx的活性都大幅度增加,但所有酶活性都明显低于活体内的酶活性。 相似文献
10.
P. W. MICHAEL 《Weed Research》1967,7(2):145-154
Summary. In phosphatase extracts prepared from untreated leaves of Onopordum acanthium , phosphatase activity was stimulated by amitrole (0·04 M) and ammonium thioeyanate (0·04 M), alone and together. The effect of the mixture of amitrole and ammonium thioeyanate was more than additive in experiments set up at pH 4·0, less than additive at pH 4·6 and roughly additive at pH 5·3 and 5·8. The effect of amitrole alone could be explained simply in terms of the increase in pH it effected.
In leaves harvested 4, 7 and 9 days after spraying rosettes with 1/8 lb/ac (140 g/ha) amitrole and 1/4 lb/ac (280 g/ha) ammonium thioeyanate, alone and together, more than additive or additive increases in phosphatase activity of plants sprayed with the mixture were recorded. These increases are interpreted as being due to increases in the amount of soluble protein.
Inorganic phosphate levels showed different trends with time in plants treated with amitrole alone compared with plants treated with the mixture of amitrole and ammonium thioeyanate.
These interactions between amitrole and ammonium thioeyanate are taken to indicate a possible chemical basis for the increased herbicidal activity of the mixture over amitrole alone.
Histochemical studies on the mature leaves of rosettes showed that phosphatase activity was confined to the vascular tissues while in the very young leaves it was high in the chlorenchymatous tissue and appreciable in the epidermal and hair cells.
Attention is drawn to the strong buffering action of amitrole in the pH range 4·0–5·3. This may be relevant to herbicidal activity, the vacuolar pH of the outer cells of leaves of Onopordum being in the range 4·8-5·2.
L'action combinée du 3-amino-1,2,4-triazole et du thioeyanate d'ammonium sur l'activité de la phosphatase chez Onopordum acanthium L. 相似文献
In leaves harvested 4, 7 and 9 days after spraying rosettes with 1/8 lb/ac (140 g/ha) amitrole and 1/4 lb/ac (280 g/ha) ammonium thioeyanate, alone and together, more than additive or additive increases in phosphatase activity of plants sprayed with the mixture were recorded. These increases are interpreted as being due to increases in the amount of soluble protein.
Inorganic phosphate levels showed different trends with time in plants treated with amitrole alone compared with plants treated with the mixture of amitrole and ammonium thioeyanate.
These interactions between amitrole and ammonium thioeyanate are taken to indicate a possible chemical basis for the increased herbicidal activity of the mixture over amitrole alone.
Histochemical studies on the mature leaves of rosettes showed that phosphatase activity was confined to the vascular tissues while in the very young leaves it was high in the chlorenchymatous tissue and appreciable in the epidermal and hair cells.
Attention is drawn to the strong buffering action of amitrole in the pH range 4·0–5·3. This may be relevant to herbicidal activity, the vacuolar pH of the outer cells of leaves of Onopordum being in the range 4·8-5·2.
L'action combinée du 3-amino-1,2,4-triazole et du thioeyanate d'ammonium sur l'activité de la phosphatase chez Onopordum acanthium L. 相似文献
11.
The effect of pH on the survival of Clavibacter michiganensis ssp. michiganensis and its transmission via roots of tomato in hydroponic culture was studied in laboratory and greenhouse experiments. In a laboratory experiment, C . m. ssp. michiganensis could not survive for 24 h in nutrient solutions with a pH of 4·0 or 4·5, while 1, 14, 51 and 62% of inoculum survived at pH 5·0, 5·5, 6·0 and 6·5, respectively. When tomato plants were inoculated with C . m. ssp. michiganensis through wounds on the stems, the bacteria moved downward from the inoculation site to the roots and infectious bacteria were released from the roots into the nutrient solution. Of two pH regimes tested in greenhouse nutrient-film technique (NFT) culture, the C . m. ssp. michiganensis population was significantly lower in pH 5·0 than in pH 6·5 in most sampling data. In treatments in which C . m. ssp. michiganensis was introduced by transplanting two root-inoculated plants, significantly more plants developed canker at pH 6·5 (34 out of 48 plants) than at pH 5·0 (11 out of 48 plants). When the bacterium was introduced by transplanting two stem-inoculated plants at pH 6·5, seven out of 24 plants developed canker. The potential of pH manipulation in controlling tomato bacterial canker in hydroponic culture is discussed. 相似文献
12.
Jiuxu Zhang Benny D. Bruton Charles L. Biles 《Physiological and Molecular Plant Pathology》1999,54(5-6)
Fusarium solani is one of the more important fungal pathogens involved in pre- and post-harvest decay of muskmelon fruit. Production of polygalacturonase (PG), by F. solani was studied in vitro and in vivo . The fungus produced at least 14 PG isozymes with pIs of 4.5 to 9.5 in shake culture using pectin as the sole carbon source. When glucose and pectin were used in combination as the carbon source, total PG activity decreased substantially as compared to pectin alone, suggesting that glucose may suppress PG production in vitro . Only one PG isozyme, designated as PG1, was detected in extracts from infected fruit tissue. PG1 from decayed fruit was purified to homogeneity by protein extraction, ultrafiltration, gel filtration chromatography, and cation exchange chromatography. The molecular weight of PG1 was estimated at 38 kDa based on SDS-PAGE with a pI of 9.5 according to IEF-PAGE. PG1 exhibited only endo-PG activity based on viscosity reduction and thin layer chromatography analysis of products released by enzymatic action. The optimum pH for PG1 activity was 6. TheKm and Vmaxof PG1 using polygalacturonic acid as the substrate were 1.34 mg ml-1and 0.30 unit μg protein-1, respectively. PG1 effectively macerated fruit tissue which suggests that it may play an important role in decay of muskmelon fruit caused by F. solani . 相似文献
13.
Phytotoxic concentrations of acetic acid were found in extracts of decaying rhizomes of couch grass ( Agropyron repens ) kept in sand at different moisture levels. Leaf extension of barley seedlings was inhibited by inoculating the radicles before planting with Fusarium culmorum and this inhibition was increased by 5 mM acetic acid. Seed dressings of benomyl and thiram alleviated the inhibition of leaf growth of seedlings grown in sand containing rhizomes inoculated with F. culmorum . 相似文献
14.
Eight Mycosphaerella graminicola isolates were investigated for correlations between pathogenicity and the in vitro production of cell wall-degrading enzymes. Isolate pathogenicity was evaluated in terms of lesion and production of pycnidia in wheat leaves. Additionally, the isolates were compared over time for their ability to produce in vitro significant levels of xylanase (EC 3·2·1·8), β-xylosidase (EC 3·2·1·37), β-1,3-glucanase (EC 3·2·1·6), cellulose (EC 3·2·1·4) and polygalacturonase (EC 3·2·1·15) activities when grown in a liquid medium. Correlation tests and principal component analysis revealed a significant correlation between the in vitro production of xylanase and pectinase and pathogenicity components. Xylanase was correlated to necrosis frequency ( r = 0·795), β-xylosidase was correlated to the mean of the lesion length ( r = −0·787), whereas polygalacturonase was correlated to the time when 50% of the leaves contained a lesion ( r = 0·776), the lesion frequency ( r = 0·646) and the time when 50% of the leaves showed pycnidia ( r = −0·711). The results suggest that these two groups of cell wall-degrading enzymes are therefore likely to be key determinants of pathogenicity in M. graminicola . 相似文献
15.
Total DNA from a cycloheximide-resistant mutant of Fusarium graminearum producing zearalenone was incubated with the protoplasts of a non-zearalenone-producing cycloheximide-susceptible isolate of F. culmorum. The regenerated protoplasts were inoculated on a 5-mM cycloheximide medium. The cultures which developed were examined for zearalenone production. Sixty-five cycloheximide-resistant isolates, including two isolates producing zearalenone, were obtained from approximately 3.6 × 104 viable F. culmorum protoplasts. Similar incubations with homologous F. culmorum DNA and non-fungal DNA did not elicit zearalenone production. The results suggest the transformation of F. culmorum by the genetic factors responsible for cycloheximide resistance and zearalenone production from F. graminearum. The epidemiological and taxonomic significance of these observations is discussed. 相似文献
16.
R.P. Baayen E.A.M. Schoffelmeer S. Toet D.M. Elgersma 《European journal of plant pathology / European Foundation for Plant Pathology》1997,103(1):15-23
Carnation cultivars with different levels of partial resistance were inoculated with race 2 of Fusarium oxysporum f.sp. dianthi and monitored for accumulation of host phytoalexins, fungal escape from compartmentalization, production of fungal pectin-degrading enzymes and development of external disease symptoms. Accumulation of phytoalexins, assessed after 10 days in the first 5 cm above the inoculation site, was weakly (methoxydianthramide S) or not (hydroxydianthalexin B) correlated with resistance levels after 12 weeks. Fungal escape from compartmentalization, assessed after 3 weeks as percentages colonized plants at 8 cm above the inoculation site, was highly correlated with expression of susceptibility after 12 weeks. Polygalacturonase (PG) activity, assessed after 4 weeks in the first 5 cm above the inoculation site, was highly correlated to final disease development. Linear increases in disease severity were accompanied by quadratic increases in PG activity. In contrast to water-treated plants, that lacked any PG activity, inoculated plants contained two main groups of fungal PGs, the dominant forms of which had estimated pI values of 7.0 and minimally 9.5, respectively. Compared to those of the first group, enzymes of the second group were produced only in trace amounts in liquid media containing pectin or polygalacturonate as sole source of carbon. On these media, the fungus also produced a pectin methyl esterase (PME) with an estimated pI of 9.3. Besides PMEs of host origin, inoculated plants of susceptible cultivars contained the fungal PME while no more than traces were found in resistant ones.Assessment of phytoalexin production by the host during defense responses cannot replace monitoring of external symptoms as a resistance test. Assessment of fungal growth, whether by reisolations above the compartmentalization area or by measurement of PG activity, provides a both rapid and reliable prediction of disease development. 相似文献
17.
I. M. J. Scholtens-Toma G. J. M. De Wit P. J. G. M. De Wit 《European journal of plant pathology / European Foundation for Plant Pathology》1989,95(1):161-168
Apoplastic fluids were isolated from the near-isogenic lines Cf2, Cf4 and Cf5 of the tomato (Lycopersicon esculentum Mill.) cultivar ‘Moneymaker’ infected with a set of newCladosporium fulvum races 2.5, 2.4.11, 2.5.9, 2.4.5.11, 2.4.9.11 and 2.4.5.9.11 and a set of previously described races 2, 4, 5, 2.4., 2.4.5 and 2.4.5.9. Upon injection of the apoplastic fluids into leaves of the near-isogenic lines Cf0, Cf2, Cf4, Cf5 and Cf9 and the genotypes carrying Cf6 and Cf11 chlorosis or necrosis was observed in all plants that were resistant to the race that initially had been used to raise the apoplastic fluid, except in the genotype Cf11 when the races 4, 2.4, 2.4.5 and 2.4.5.9 from our own collection were involved. The latter races may contain virulence gene all as our collection had not yet been checked for presence of this virulence gene. Apoplastic fluids of all races induced chlorosis on the genotype carrying resistance gene Cf6, a gene which has not yet been overcome by any of the presently described races ofC. fulvum.Low pH non-denaturing polyacrylamide gel electrophoresis showed that apoplastic fluids of compatible interactions with the new races 2.5.9, 2.4.9.11 and 2.4.5.9.11 carrying the virulence gene a9, like the previously described race 2.4.5.9, did not contain the necrosis-inducing peptide, while the peptide was present in all races carrying avirulence gene A9. This indicates that this race-specific elicitor is strongly associated with avirulence gene A9 and is possibly its product as has been suggested previously. 相似文献
18.
咯菌腈对西瓜幼苗生长及抗病性相关酶活性的影响 总被引：2，自引：0，他引：2
测定了有效成分为咯菌腈的2.5%适乐时悬浮种衣剂包衣处理西瓜种子后对种子发芽、幼苗生长及其植株体内抗病性相关酶活性的影响。结果表明,种衣剂包衣对种子发芽率以及幼苗的子叶宽度、侧根数和百株鲜重无显著影响;幼苗子叶长度和株高分别增加了4.8%和7.5%,植株体内丙二醛的积累量下降了7.7%,可溶性蛋白含量增加了2.2%;过氧化物酶、过氧化氢酶、多酚氧化酶和苯丙氨酸解氨酶的含量分别较对照提高了62.9%、46.5%、35.6%和44.1%,与对照相比,差异显著。说明咯菌腈处理西瓜种子后发芽安全,并能促进幼苗生长,提高抗病性相关酶的活性。 相似文献
19.
Thick root is a relatively new disorder of cucumber grown in artificial substrates. Plants of cucumber, tomato, sweet pepper, lupin, anthurium, Cucurbita ficifolia , C. maxima and two lines from crosses between C. maxima and C. moschata were grown in thick root disease (TRD)-infested nutrient solutions containing the TRD agent. Plants from each species or line, except anthurium, developed TRD symptoms. Growth of diseased plants, except those of the line C. maxima × C. moschata RS841, was significantly reduced compared with the nondiseased controls. Two weeks after infestation, by adding TRD-affected nutrient solution to fresh nutrient solution, the presence of the infective TRD agent was shown in each of the nutrient solutions in which the plants had been grown, including anthurium. No infective TRD agent could be shown in nutrient solution that had not been in contact with roots of living plants. The minimum pH for thick root formation was shown to be between 5·0 and 5·5. Nutrient solutions with pH values ranging from 4·0 to 6·5 and infested with the TRD agent lost their infectivity within 8 days. The infective period decreased with decreasing pH (pH 4·0–6·5) and a pH effect on the infectivity of a nutrient solution was shown within 1 h of infestation. The data show that the risk of TRD can be reduced by decreasing the pH of the nutrient solution. 相似文献
20.
The take-all fungus, Gaeumannomyces graminis var. tritici , was highly sensitive to fluquinconazole ( in-vitro EC50 0·016–0·018 mg L−1 ), a fungicide developed for use as a seed treatment to control take-all, and to prochloraz (EC50 0·006 mg L−1 ). Fungi of other genera that were commonly isolated from cereal roots were sensitive in varying degrees to prochloraz but were relatively insensitive (e.g. Fusarium culmorum , EC50 > 20 mg L−1 ) or slightly sensitive (e.g. Epicoccum purpurascens , EC50 0·514 mg L−1 ) to fluquinconazole. Gaeumannomyces graminis var. graminis and G. cylindrosporus , weak parasites that can protect roots against take-all, and an unnamed Phialophora sp., all closely related to the take-all fungus, were highly or moderately sensitive to fluquinconazole. Alternaria infectoria and E. purpurascens were most consistently effective in suppressing development of take-all on pot-grown wheat plants dual-inoculated with G. graminis var. tritici and the nonpathogen. Take-all was decreased more on dual-inoculated wheat plants grown from seed treated with fluquinconazole or fluquinconazole plus prochloraz than when only an antagonistic fungus ( A. infectoria , E. purpurascens , Fusarium culmorum or Idriella bolleyi ) or a seed treatment was applied. These fungi were less effective in combination with seed treatments on barley. Gaeumannomyces graminis var. graminis and G. cylindrosporus , tested on wheat, suppressed take-all only in the absence of fungicides. It is suggested that the performance of seed treatment containing fluquinconazole against take-all may in some circumstances be enhanced by its partial specificity for the take-all fungus. 相似文献