Showing papers by "Ali H. Bahkali published in 2013"

Families of Dothideomycetes

Abstract: Dothideomycetes comprise a highly diverse range of fungi characterized mainly by asci with two wall layers (bitunicate asci) and often with fissitunicate dehiscence. Many species are saprobes, with many asexual states comprising important plant pathogens. They are also endophytes, epiphytes, fungicolous, lichenized, or lichenicolous fungi. They occur in terrestrial, freshwater and marine habitats in almost every part of the world. We accept 105 families in Dothideomycetes with the new families Anteagloniaceae, Bambusicolaceae, Biatriosporaceae, Lichenoconiaceae, Muyocopronaceae, Paranectriellaceae, Roussoellaceae, Salsugineaceae, Seynesiopeltidaceae and Thyridariaceae introduced in this paper. Each family is provided with a description and notes, including asexual and asexual states, and if more than one genus is included, the type genus is also characterized. Each family is provided with at least one figure-plate, usually illustrating the type genus, a list of accepted genera, including asexual genera, and a key to these genera. A phylogenetic tree based on four gene combined analysis add support for 64 of the families and 22 orders, including the novel orders, Dyfrolomycetales, Lichenoconiales, Lichenotheliales, Monoblastiales, Natipusillales, Phaeotrichales and Strigulales. The paper is expected to provide a working document on Dothideomycetes which can be modified as new data comes to light. It is hoped that by illustrating types we provide stimulation and interest so that more work is carried out in this remarkable group of fungi.

A novel Trichoderma species isolated from soil in Guizhou, T. guizhouense

Abstract: A new species of Trichoderma, Trichoderma guizhouense, isolated from soil in Guizhou Province, is described based on morphology and phylogenetic analyses. This species exhibits characteristic Trichoderma morphology but is distinct from related species based on characters of phialides and conidia. Two DNA markers, the translation elongation factor 1 alpha (tef1) and RNA polymerase II subunit b (rpb2) were used for phylogenetic analyses. The correlation between morphological and molecular-based clustering demonstrated two studied isolates are a new species.

Deniquelata barringtoniae gen. et sp. nov., associated with leaf spots of Barringtonia asiatica

Abstract: Deniquelata barringtoniae gen. et sp. nov. ( Montagnulaceae ) forms numerous ascomata on distinct zonate leaf spots of Barringtonia asiatica ( Lecythidaceae ). We isolated this taxon and sequenced the 18S and 28S nrDNA. The result of phylogenetic analysis based on 18S and 28S nrDNA sequence data indicate that the genus belongs in the family Montagnulaceae , Dothideomycetes , Ascomycota . The ascomata are immersed, dark brown to black, with bitunicate asci and brown, muriform ascospores. Deniquelata is distinguished from the other genera in Montagnulaceae based on its short, broad, furcate and pedicellate asci, verruculose ascospores with short narrow pseudoparaphyses with parasitic naturee and this is also supported by molecular data. A new genus and species is therefore introduced to accommodate this taxon. We used isolates of this species to show via pathogenicity testing that the taxon is able to cause leaf spots when leaves are pin pricked.

Halotthiaceae fam. nov. (Pleosporales) accommodates the new genus Phaeoseptum and several other aquatic genera

Abstract: During survey of freshwater fungi in Haute Garonne in the Pyrenees (southern France), we collected a remarkable species that is most comparable to the maritime fungus Mauritiana rhizophorae. The maritime genera Halotthia, Pontoporeia and Mauritiana as well as our newly collected species form a monophyletic clade in phylograms generated from LSU rDNA sequence analyses. This clade has undetermined familial status, and our new species is not congeneric with Halotthia, Pontoporeia or Mauritiana. A new monotypic genus, Phaeoseptum (represented by Ph. aquaticum sp. nov), therefore is introduced to accommodate the newly collected freshwater taxon. A new family, Halotthiaceae, is introduced to accommodate the four aquatic genera Halotthia, Mauritiana, Phaeoseptum and Pontoporeia.

Stachybotrys from soil in China, identified by morphology and molecular phylogeny

Abstract: Four Stachybotrys strains were isolated from soil in China. One was identified as a novel species by morphological characters of phialides and conidia. It produced cylindrical conidia with irregular striations and smooth, hyaline conidiophores. Phylogenetic analysis of three DNA markers, the internal transcribed spacer region of rDNA (ITS1–5.8S–ITS2), the translation elongation factor 1 alpha (tef1) and RNA polymerase II subunit (rpb2), supported the morphological results. The correlation between morphological and molecular-based clustering demonstrated that the studied isolate was a new species. Two other isolates were identified as S. cf. elegans.

A polyphasic method for the identification of aflatoxigenic 'Aspergillus' species isolated from Camel feeds

Abstract: The main goal of our study was to identify Aspergillius spp. isolates by polyphasic taxonomic techniques. Differential culture media, biochemical and molecular characterization were applied to 21 isolates of Aspergillus flavus and Aspergillus niger from Saudi Arabia camel feeds. Six aflatoxin producing culture media were used for characterizing and identifying aflatoxigenic isolates. The blue fluorescent ring visible under UV light which indicates the ability to produce aflatoxin, by aflatoxinogenic strains was not observed for any of the tested non aflatoxigenic isolates. Biochemical characterization involving the screening of the isolates for five aflatoxins was also performed. As found, most isolates were capable of producing detectable levels of both B and G type's aflatoxins (AFs) and maltoryzine, although 4 of the 7 A. niger isolates failed to produce any detectable amount of AFs. PCR was performed using one set of primers that specifically targets the aflatoxin regulatory gene (aflR) involved in aflatoxin biosynthetic pathway as well as four specific primers for A. flavus and A. niger. The presence of the aflR gene did not correlate with aflatoxigenicity. Most of the fungi belonging to A. flavus group reacted positively with aflR primers that cover the region from 540 to 1338 of aflatoxin regulatory gene with product size of 798 base pairs (bp). All A. flavus isolates had positive PCR results using the primer pair FLA1-FLA. A unique DNA fragment of the expected 500-bp size was amplified in all A. flavus isolates, while no PCR products were visualized in other Aspergillus species or members belong to other fungal genera. Using the primer pairs OMt1R-OMt1F, a single fragment of about 1232 bp A. niger isolates was amplified but did not amplify with DNA extracted from other Aspergillus species or species belonging to other fungal genera. Detection and quantification of these two important aflatoxin-producing Aspergilli could provide important information to predict the aflatoxin profiles which may be present in the feed matrix.

One-hour loop-mediated isothermal amplification assay for the detection of quarantinable toxigenic Fusarium garmanirum

Abstract: Fusarium head blight (FHB) caused by several Fusarium species is one of the most serious diseases affecting wheat throughout the world. The in vitro production of the toxins deoxynivalenol, zearalenone fumonisin, T-2, and HT-2 was quantitvely evaluated in 8 different isolates of Fusarium species collected from feed samples. It was possible to detect zearalenone and the other mycotoxins in 100% and 50% of the isolates, respectively. In the present study, loop-mediated isothermal amplification method (LAMP) was designed for diagnosing Fusarium garmanirum infections and testing against feed samples, infested samples and pure cultures. The LAMP amplicon was directly visualized in the reaction tubes by the naked eye following the addition of calcein fluorescence. The LAMP products appeared as DNA marker pattern, with many bands of different sizes from 145 base pairs up to the loading well. Loop-LAMP procedure was used to detect genomic DNA of F. graminearum in fungal pure culture and in contaminated feed samples. In the future, this assay will support plant quarantine programs in Saudi Arabia and Gulf Cooperation Council states, to prevent the introduction of foreign FHB species. Key words: LAMP-PCR, Fusarium head blight, feed samples.

Biological Control of Root Rots and Stems Canker of Tomato Plants Caused by Rhizoctonia solani in Saudi Arabia

Abstract: Eight antagonistic fungi; Chaetomium spp., Aspergillus versicolar, A. terreus, Talaromyces (Penicillium) wortmanni, Epicoccum sp., Trichoderma viride, T. harzianum and T. hamatum were isolated from sclerotia of R. solani infested tomatoes growing under greenhouse in Riyadh, Saudi Arabia. T. hamatum, T. harzianum, T. viride and A. terreus were the most antagonistic against R. solani by 94.44, 93.89, 92.22 and 75.22% reduction in mycelia growth, respectively. Where, A. terreus and T. viride were found to affect sclerotial viability of R. solani, caused 100% mortality of sclerotia. Greenhouse tests showed that the most effective treatment was the amendment of pathogen-infested soil by T. hamatum and T. viride which resulted in a disease severity of 12.50 and 12.90%, respectively compared to controls. Application of bioagents soil fungi significantly increased biomass of total fresh weight. The highest of biomass% (47.02) was observed in T. harzianum and the lowest biomass% (2.86) was obtained with A. terreus.

Developments in using fatty acids in fungal chemotaxonomy

Abstract: The cellular fatty acid composition of nine species of Fusarium; namely, Fusariumanthophilum, F. avenaceum, F. cerealis, F. graminearum, F. graminum, F. oxysporum f. sp. conglutinans, F. pseudograminearum, F. roseum and F. sacchari var. elongatumgrowing on malt extract medium were determined. The fatty acid profiles of the investigated fungi showed very little variation and could only differentiate between few species. However, by adding certain chemical compounds including aspartic acid, glutamic acid, methionine, selenium and urea to the growth medium, the variation of the fatty acid profile was greatly increased and differentiated between all the investigated fungi. For example, pentadecanoic acid was not produced by F. anthophilum on malt extract broth (MEB) but only produced on MEB supplemented with aspartic acid. On the other hand, linolenic fatty acid was neither produced by F. anthophilum nor F. roseumgrown on MEB, but it was produced by F. anthophilum in presence of aspartic acid and byF. roseum in the presence of glutamic acid. The fatty acid profiles could be useful for characterization and identification of fungi if determined under different conditions. Key words: Fungal chemotaxonomy; fatty acids; Fusarium spp.; environmental conditions.

Pathogenicity of Scleritinia sclerotiorum to Bean (Phaseolus vulgaris, L.) Cultivars

Abstract: Sclerotinia rot caused by Sclerotinia sclerotiorum is a serious threat to green beans production in Egypt. The pathogenicity of this pathogen to 11 different cultivars was measured by survival plants % in the genotypes. Significant differences were observed between different cultivars (P0.05). Results indicate that, Amy and Giza cultivars were more susceptible to infection with S. sclerotiorum that produced 16% survival plants in both cultivars after 60 days. While, Duel cultivar was less sensitive to infection with the pathogen that giving 40% living plants at 60 days.

Improved method for DNA isolation from different types of soil infested with three fungal genera.

Abstract: In the current study, we describe a DNA isolation method that is based on an easy, quick polyvinylpolypyrrolidone-precipitation to release phytofungi from the soil, combined with lysozyme- RNase and -SDS lysis of the fungal population. DNA extracts were subjected to different techniques, including gel electrophoresis, restriction enzyme digestion, RAPD and ITS-PCR amplification. The proposed method yielded high-quality DNA, which was transparent, non-viscous and lacked visible contamination of RNA. Isolated DNA was efficiently digested with restriction enzymes. DNA extracted from soil was pure enough to be utilized at high concentrations for PCR amplifications. The extracted DNA was of high quality and allowed direct detection of specific genes by the polymerase chain reaction (PCR). The amplicon length of the fragment ITS4/ITS5, ranged in size from 550 to 680 bp. A polymerase chain reaction method used to detect soil-borne plant pathogens such as Fusarium spp. , Rhizoctonia solani and Macrophomina phaseolina in the soil was developed and used with a range of soil textures. A direct method for the extraction of DNA from soil samples, which can be used for PCR-mediated diagnostics without a need for further DNA purification, was developed. The developed protocol seemed adequate to the range of soil textures that were artificially infested by a variety of soil-borne pathogens.