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Copyright of Assiut Journal of Agricultural Sciences is the property of Egyptian National Agricultural Library (ENAL) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The plant growth-promoting fungus, Penicillium simplicissimum GP17-2, was evaluated for its ability to induce resistance against Cucumber mosaic virus (CMV) in Arabidopsis thaliana and tobacco plants. Treatment with barley grain inoculum (BGI) of GP17-2 significantly enhanced fresh weight, dry weight and leaf number of A. thaliana and tobacco plants 6 weeks after planting. Two weeks after CMV inoculation, all plants treated with BGI of GP17-2 or its culture filtrate (CF) showed a significant reduction in disease severity compared with non-treated control plants, which exhibited severe mosaic symptoms by the end of the experiment. The enzyme-linked immunosorbent assay (ELISA) demonstrated that CMV accumulation was significantly reduced in plants treated with GP17-2 or its CF relative to control plants. Based on RT-PCR, plants treated with GP17-2 (BGI or CF) also exhibited increased expression of regulatory and defence genes involved in the SA and JA/ET signalling pathways. These results suggested that multiple defence pathways in A. thaliana and tobacco were involved in GP17-2-mediated resistance to CMV, although neither the transgenic NahG line, nor the npr1, jar1 or ein3 mutants disrupted the response in A. thaliana. This is the first report to demonstrate the induction of systemic resistance against CMV by GP17-2 or its CF. [ABSTRACT FROM AUTHOR]

To alleviate the environmental contamination due to persistent chemical usage, approaches to integrated pest management were conceived. In this perspective, microbe-microbe interactions such as mycorrhizal relationships with other soil microbiota in the rhizosphere like the plant growth-promoting fungi (PGPF) are particularly important. Better understanding of the interactions between beneficial microbial groups is imperative in the identification of possible synergistic or antagonistic effects to improve their practical usage as biocontrol agents or biofertilizers. In this study, the consequence of co-inoculation of the arbuscular mycorrhizal fungus (AMF) Glomus mosseae (Gm) and the PGPF Fusarium equiseti (isolates GF18-3 and GF19-1) in terms of plant growth enhancement, root and rhizosphere colonisation, and development of anthracnose ( Colletotrichum orbiculare) and damping-off ( Rhizoctonia solani AG-4) diseases in cucumber plants was investigated under controlled conditions. The amendment of either GF18-3 or GF19-1 singly or in combination with Gm indicated a general tendency to significantly enhance the shoot dry weight (SDW) of cucumber plants at 4 weeks after planting (WAP). Similarly, Gm alone significantly enhanced SDW at 4 WAP. Gm showed a tendency to depress root colonisation by F. equiseti but such antagonistic effect was not observed in the rhizosphere soil. Both GF18-3 and GF19-1 significantly reduced percent root colonisation of Gm. However, these general tendencies may vary with the inoculum densities of AMF and PGPF. Both F. equiseti and Gm inoculated singly significantly increased percent of protection against anthracnose, but the combined inoculation was more effective in controlling the disease compared to single inoculation. The inoculation of the cucumber seedlings with GF18-3, GF19-1 or Gm, 6 or 12 days prior to damping-off pathogen inoculation, increased percent of protection against damping-off disease. This study shows that the co-inoculation of F. equiseti and Gm resulted in additive effect on the suppression of anthracnose disease in cucumber. [ABSTRACT FROM AUTHOR]

The plant growth-promoting fungus (PGPF), Phoma sp. GS8-3, isolated from a zoysia grass rhizosphere, is capable of protecting cucumber plants against virulent pathogens. This fungus was investigated in terms of the underlying mechanisms and ability to elicit systemic resistance in Arabidopsis thaliana. Root treatment of Arabidopsis plants with a culture filtrate (CF) from Phoma sp. GS8-3 elicited systemic resistance against the bacterial speck pathogen Pseudomonas syringae pv. tomato DC3000 ( Pst), with restricted disease development and inhibited pathogen proliferation. Pathway-specific mutant plants, such as jar1 (jasmonic acid insensitive) and ein2 (ethylene insensitive), and transgenic NahG plants (impaired in salicylate signalling) were protected after application of the CF, demonstrating that these pathways are dispensable (at least individually) in CF-mediated resistance. Similarly, NPR1 interference in npr1 mutants had no effect on CF-induced resistance. Gene expression studies revealed that CF treatment stimulated the systemic expression of both the SA-inducible PR-1 and JA/ET-inducible PDF1.2 genes. However, pathogenic challenge to CF-treated plants was associated with potentiated expression of the PR-1 gene and down-regulated expression of the PDF1.2 gene. The observed down-regulation of the PDF1.2 gene in CF-treated plants indicates that there may be cross-talk between SA- and JA/ET-dependent signalling pathways during the pathogenic infection process. In conclusion, our data suggest that CF of Phoma sp. GS8-3 induces resistance in Arabidopsis in a manner where SA and JA/ET may play a role in defence signalling. [ABSTRACT FROM AUTHOR]

Cucumber plants were treated with plant growth promoting fungi (PGPF), Phoma sp. (isolates GS8-2 and GS8-3) and Penicillium simplicissimum (isolate GP17-2) with or without the arbuscular mycorrhizal fungus (AMF) Glomus mosseae. Induction of systemic resistance in cucumber against the anthracnose disease caused by Colletotrichum orbiculare was tested to evaluate the nature of the interaction between the PGPF and AMF. Root colonizing ability of each fungal species as influenced by their interaction was also evaluated. Plant roots were pre-inoculated with each PGPF isolate and/or G. mosseae for four weeks and leaves were then challenge inoculated with the pathogen C. orbiculare. Plants treated with each PGPF isolate showed considerable protection against the disease, but the treatment of G. mosseae had no significant effect on disease development. However, combined inoculation of Phoma GS8-2 or GS8-3 with G. mosseae reduced the level of disease protection induced by single inoculation of each Phoma isolate. In contrast, the high levels of protection induced by the P. simplicissimum GP17-2 were not altered by combining it with G. mosseae. Root colonization of both Phoma sp. isolates was also suppressed by the presence of the G. mosseae, but such an effect was not found on the population development of P. simplicissimum. The percent cucumber root length colonized by G. mosseae was not affected by any of the PGPF isolates tested. [ABSTRACT FROM AUTHOR]

Isolates of Rhizoctonia solani AG 2 from tobacco (Ntisolates) were reported to anastomose with isolates of AG-BI in high frequency (fusion frequency [FF] ≥ 50%) compared to isolates of AG 2-1 (FF < 50%), even though mature culture and thiamine requirement of the isolates were closely similar to AG 2-1. In this study, whole-cell fatty acid compositions of Nt-isolates (four isolates), isolates of AG 2-1 (eight isolates) and AG-BI (two isolates) were compared by gas-liquid chromatography analysis. Four isolates of AG 2 from tulip (AG 2-t) were also included. Palmitic (16:0), oleic (18: 1 cis9) and linoleic (18 : 2 cis9,12) acids were the three major fatty acids identified which constituted 89.6-93.4% of whole-cell fatty acid content. Myristic (14 : 0), pentadecanoic (15 : 0), palmitoleic (16 : 1 cis9), stearic (18 : 0) and linolenic (18 : 3 cis9,12) acids were present at low levels. Heptadecanoic (17 : 0) and 9-heptadecenoic (17 : 1 cis9) acids were also present in Nt-isolates and isolates of AG 2-1 but not in isolates of AG 2-t and AG-BI. With the exception of oleic acid, percentage composition of fatty acids of Nt-isolates were similar with those of isolates of AG 2-1 and AG 2-t but were different from isolates of AG-BI. Although fatty acid compositions of Nt-isolates and isolates of AG 2-1 were qualitatively and quantitatively similar, principal component and cluster analyses based on all detected fatty acids showed separation of the former from the latter groups indicating that Nt-isolates are a homogenous population in AG 2-1. Additionally, isolates of AG 2-t were closely related to isolates of AG 2-1. Isolates of AG-BI were distinctly separated from isolates of AG 2-1, AG 2-t and Nt-isolates. Results of fatty acid analysis support the designation of Nt-isolates as a member of AG 2-1 based on sequence similarity of rDNA-ITS. [ABSTRACT FROM AUTHOR]

Monoclonal antibodies (MAbs) were raised against surface antigens from Pythium sulcatum . The immunogens were prepared from salt extractable cell wall protein to produce monoclonal antibodies. The MAbs showed high specificity to seven P. sulcatum isolates among 26 species of soil-borne fungi. Weak cross-reactivities were observed with Pythium aristosporum , Pythium myriotylum , and Pythium zingiberum in indirect enzyme-linked immunosorbent assay (ELISA), but no reaction was obtained in Western blot analysis. The MAbs recognized glycoproteins in cell wall. Pythium sulcatum was detected in naturally infected carrot tissues and soil using indirect competition ELISA. [ABSTRACT FROM AUTHOR]

Cellular fatty acid analysis was employed to differentiate three varieties of Rhizoctonia circinata; var. circinata, var. oryzae and var. zeae. Eight fatty acids including myristic (14:0), pentadecanoic (15:0), palmitic (16:0), palmitoleic (16:1 cis9), stearic (18:0), oleic (18:1 cis9), linoleic (18: 2 cis9,12) and linolenic (18: 3 cis9,12) acids were present in isolates of all three varieties of R. circinata. Heptadecanoic acid (17:0) was detected in isolates of R. circinata var. zeae but not in isolates of R. circinata var. circinata or R. circinata var. oryzae. Palmitic, oleic and linoleic acids were the major fatty acids found, comprising 94-98% of the whole-cell fatty acid content. The remaining fatty acids were present in small amounts. Based on the composition (%) of fatty acids, isolates of R. circinata var. circinata, R. circinata var. oryzae and R. circinata var. zeae were clearly differentiated into three groups as shown by principal component and cluster analyses. This finding agrees well with the grouping of R. circinata into three varieties based on differences in colony morphology of the vegetative state. In principal component and cluster analysis, isolates of R. circinata var. circinata from Japan and Alaska were indistinguishable. [ABSTRACT FROM AUTHOR]

Whole-cell fatty acid compositions of binucleate Rhizoctonia AG-D (R. cerealis) isolates representing subgroups I [AG-D (I)] and II [AG-D (II)] obtained from various host plants were compared. Ten fatty acids including myristic (14 : 0), pentadecanoic (15 : 0), palmitic (16 : 0), palmitoleic (16 : 1 cis9), heptadecanoic (17 : 0), 9-heptadecenoic (17 : 1 cis9), stearic (18 : 0), oleic (18 : 1 cis9), linoleic (18 : 2 cis9,12) and linolenic (18 : 3 cis9,12) were consistently present in all isolates of Rhizoctonia AG-D. The major fatty acids found were palmitic, oleic and linoleic acids, comprising 88–93% of the whole-cell fatty acid content. The remaining fatty acids were present in smaller amounts ranging from 0.01 to 5.03% of the whole-cell fatty acid content. Palmitic and oleic acids were present in approximately two and three times higher concentrations in isolates of AG-D (I) than in isolates of AG-D (II), respectively. On the other hand, linoleic acid was about two times lower in isolates of AG-D (I) than in isolates of AG-D (II). Principal component and cluster analyses of the percentage composition of fatty acids showed distinct separation between AG-D (I) and AG-D (II). The results indicated that fatty acid analysis is useful for differentiating AG-D (I) and AG-D (II) and supported previous differentiation of the two subgroups on the basis of cultural characteristics, pathogenicity and DNA analyses. In addition, a Rhizoctonia AG-Q isolate from bentgrass and Rhizoctonia AG-D isolates causing foot rot of wheat and stem rot of mat rush were grouped in AG-D (I), based on the percentage composition of fatty acids. [ABSTRACT FROM AUTHOR]

The mycorrhizal status of Clethra barbinervis, in the family Clethraceae of the order Ericales, was investigated. Mycorrhizal colonization of C. barbinervis roots collected from naturally occurring trees in two forests in Japan was determined monthly for 12 months. In addition, mycorrhizal colonization of C. barbinervis seedlings grown in pots of field-collected soil was evaluated. Field-collected C. barbinervis roots were extensively colonized by arbuscular mycorrhizal fungi that exhibited the Paris-type morphology. At both sites, total colonization ranged from 42–87% of root length and arbuscular colonization ranged from 6–31% of root length during the year. At one site, hyphal-coil colonization was between 37–61% year round; at the other site, it increased from between 30–56% during August-November to as high as 80% in January. Year round at both sites, vesicular colonization was 7% of root length or less. The Paris-type morphology was also seen in pot-grown C. barbinervis seedlings. Total colonization of pot-grown C. barbinervis seedlings was 34–56% of the root length over 5–20 weeks. To our knowledge, this study is the first report of the mycorrhizal status of a plant in the Clethraceae and the first report of arbuscular mycorrhizae in any member of the Ericales.Key words: Paris-type, Japan, seasonal pattern, arbuscular mycorrhiza, Ericales.Les auteurs ont examiné le statut mycorhizien du Clethra barbinervis, de la famille des Cletraceae, ordre des Ericales. Chaque mois, pendant 12 mois, ils ont observé la mycorhization de racines du C. barbinervis prélevées sur des arbres venant naturellement dans deux forêts, au Japon. De plus, ils ont évalué la colonisation mycorhizienne de plantules du C. barbinervis cultivées en pots, à partir de sols récoltés sur le terrain. Les racines du C. barbinervis récoltées sur le terrain sont abondamment colonisées par des champignons mycorhiziens arbusculaires ayant la morphologie du type Paris. Sur les deux stations, la colonisation est de 42–87% de la longueur des racines et la colonisation arbusculaire se retrouve sur 6–31% de la longueur des racines, au cours de l'année. Sur un des sites, la colonisation par des hyphes pelotonnées est de 37–61% au cours de l'année; sur l'autre site, elle augmente de 30–56%, entre août et novembre, pour atteindre un maximum de 80%, en janvier. Au cours de l'année, et sur les deux sites, la colonisation vésiculaire est de 7% ou moins de la longueur. On observe également la morphologie du type Paris sur les plantules du C. barbinervis cultivées en pots. La colonisation des plantules du C. barbinervis a atteint 34–56% de la longueur des racines, sur 5–20 semaines. Selon les auteurs, cette étude fait mention pour la première fois du statut mycorhizien d'une plante de la famille des Cletraceae; il s'agit également de la première mention de la présence de mycorhizes arbusculaires chez un membre quelconque de l'ordre des Ericales.Mots clés : type Paris, Japon, patron saisonnier, mycorhizes arbusculaires, Ericales.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

Two-hundred and forty-eight isolates of Rhizoctonia spp. were obtained from 13 locations in Gifu Prefecture in Japan using the plant debris particles isolation, colonization of bait tissue, and soil-clump plating methods. Of the isolates, 143 were binucleate Rhizoctonia spp., 60 were R. solani and 45 were R. zeae. Three isolates of R. solani and 54 of binucleate Rhizoctonia spp, were hypovirulent on radish, whilst all isolates of R. zeae were highly virulent, Hypovirulent strains were isolated most frequently by the plant debris particles isolation method. Hypovirulent isolates of R. solani belonged to anastomosis group 4, whilst the hypovirulent binucleate Rhizoctonia isolates belonged to AG A, AG Ba, AG G, and AGO. Thirty-two isolates of Rhizoctonia spp. selected for hypovirulence on radish were tested on cucumber in vitro. Only five binucleate Rhizoctonia isolates and one R. solani isolate were hypovirulent on both species, and these isolates were also hypovirulent on seven other crop species. Cucumber showed wide variation in disease susceptibility to different isolates but hypovirulent isolates exhibited a consistent reaction on five different host cultivars. Pathogenicity tests using cucumber grown in soil also showed consistent reactions with isolates selected either for hypovirulence or virulence. The results support the use of cucumber in bioassays for identifying hypovirulent isolates of binucleate Rhizoctonia spp. [ABSTRACT FROM AUTHOR]

A buried-slide method of inducing teleomorph development was compared with a soil method for isolates of Rhizoctonia solani in anastomosis group 2. The teleomorph (Thanatephorus cucumeris) developed frequently in the buried-slide method. For non-self-anastomosing isolates, which cannot grow through soil, the teleomorph was observed only in the buried-slide method. One of the five soils tested was particularly favourable. The buried-slide method allows easy examination of the teleomorph with minimum disturbance to the hymenium. It has demonstrated the identity of non-self-anastomosing isolates with T. cucumeris. [ABSTRACT FROM AUTHOR]