MYCOLOGIA IRANICA
Year:2014 | Volume:1 | Issue:2|Papers Count:9

The powdery mildews belong to Ascomycota (Erysiphales) and are easily recognized by their conspicuous epiphytic mycelium. Anamorph state of most teleomorphic genera with exclusively external mycelium belong to the genus Oidium. Oidium states show a great deal of variation in morphology. Conidia are produced either in chains (Euoidium-type of the genus Oidium) or solitarily (Pseudoidium-type of the genus Oidium) which are hyaline, one-celled, uninucleate, vacuolate and thin-walled (Braun 1987). The length/width ratio and shape of conidia and foot-cells are usable for taxonomic purposes. The conidia of most Oidium species vary from cylindric, ellipsoid, ovoid to doliform and their surface is usually smooth. Khodaparast et al. (2000, 2001) and Pirnia et al. (2005–2007) have reported new species of powdery mildews in Iran.

The genus Geosmithia (Ascomycota: Hypocreales) belongs to mitosporic filamentous fungi with a worldwide distribution (Kolařík et al. 2011). This genus is characterized by penicillium-like conidio- phores with roughened walls, cylindrical phialides and smooth ellipsoidal to cylindrical conidia, forming long persistent chains (Kolařík & Kirkendall 2010; Sohn et al. 2013). Geosmithia species are found in soil, plant debris and wood and can act as true endophytes of healthy trees. Most species are known as exclusive associates of many insects invading phloem or sapwood of various plants (Kolařík et al. 2007; Kolařík & Kirkendall 2010; Moubasher & Soliman 2011).

The history of mycology in Iran is presented in five periods. In the first period (until 1860) there is no sign of Iranian fungi in scientific literature. In the second period (1860–1941) the study of Iranian fungi was started by foreign mycologists who did not visit Iran but worked on plant material collected by botanists. In the third period (1941–1963) the study of Iranian fungi was started by a first generation of Iranian mycologists and also fungal plant pathology was started in Iran. A second generation of Iranian mycologists used pure culture technique in the fourth period (1963–2000). In this period mycology was taught separately from botany and plant pathology at universities, and MSc and PhD courses were initiated at some universities. In the fifth period (from 2000), a third generation of Iranian mycologists used molecular techniques to study Iranian fungi. An Asian Mycological Congress was held in Iran in 2001; the Iranian Mycological Society was founded in 2010; an MSc course of mycology was initiated at Esfahan University; the first Iranian Mycological Congress was held at Gilan University in 2013, and the first Iranian mycological journal (Mycologia Iranica) was launched.

In this paper, the taxonomy of some previously reported taxa as Cercospora apii s. lat. in Iran is discussed and some new records are listed. Cercospora species on Abelia grandiflora (C. deutziae), Erythrina crista-galli (C. erythrinicola), Euphorbia heterophylla (C. pulcherrimae) and Zanthedeschia aethiopica (C. richardiicola) are new for mycobiota of Iran. Cercospora iridis which has been previously reported from Iran probably belongs to the genus Passalora, but more specimens should be examined for final conclusion.

Fusarium solani is the most important pathogen of a variety of host plants worldwide, especially potato, which causes tuber rot in storage and root rot of potato plants in the field. Fifty four isolates obtained from potato, common bean, chickpea and cucurbits (melon, watermelon and cucumber) were subjected to analysis of vegetative compatibility groups (VCGs) and rep-PCR DNA fingerprinting. Nit mutants were used to force heterokaryon formation to determine VCGs. Twenty three groups were determined, which were designated as VCG A to VCG W. VCG A was the largest group with 18 isolates and VCG B, VCG C and VCG D were composed of 8, 6 and 3 isolates, respectively. Other groups were identified as two or single-member VCGs. Presence of a high degree of single-member VCGs indicates the large amount of genetic diversity among isolates. Further- more, the isolates of each host are classified in different VCGs. Dendrogram generated using data of rep-PCR, suggests a high level of genetic diversity among the isolates. No correlation was found between the DNA fingerprinting groups and host or geographical origin of the isolates. Pathogenicity of twenty three F. solani isolates as VCGs representatives originated from different hosts was examined on plants and tubers of Agria cultivar of potato. Except for four and two isolates, other isolates were pathogenic on potato plants and tubers, respectively. Pathogenicity tests demonstrated that F. solani isolates do not have a host specific behavior and isolates obtained from the non-potato hosts are able to cause disease on potato plants and tubers.

Fifteen non-aflatoxigenic strains of Aspergillus flavus, representing a wide range of geographic regions of Iran (six provinces including Fars, Ardebil, Guilan, Golestan, Kerman and Semnan) and vegetative compatibility groups (VCGs) were collected from corn (Zea mays L.), peanut (Arachis hypogaea L.) and pistachio (Pistachia vera L.) soils and kernels, and were screened for the presence of aflatoxin biosynthesis genes in relation to their capability to produce aflatoxins, targeting the regulatory genes afIR and aflJ, the structural genes aflT, pksA,ver-1, omtA, omtB, aflD, ordA, verA, norA, hypA, norB, cypA, sugar utilization gene glcA and flanking region gene C3 (5' end) by PCR method. This process resulted in grouping of A. flavus strains into twelve different amplification patterns (I-XII), characterized by 10-14 different DNA bands. Our results reveal that aflatoxin biosynthesis regulatory genes (aflR and aflJ) and the structural gene hypA are more important genes to detect non-aflatoxigenic strains of A. flavus. For non-aflatoxigenic strains of A. flavus, no relationship was observed between the deletion pattern and geographic origin and/or VCG; which may indicate that non-aflatoxigenic strains of A. flavus did not originate independently at each locality. It is concluded that the aflatoxin gene cluster variability existing in the non-aflatoxigenic popula- tions of A. flavus can be useful for understanding the toxicological risk as well as the selection of biocontrol agents.

Rhizoctonia-like fungi were isolated from the infected roots of miniature rose (Rosa hybrida cv. Linda) plant with chlorosis and necrosis symptoms, grown in commercial glasshouse in Rafsanjan, Iran, during the autumn of 2011. All of the isolates were identified as binucleate Rhizoctonia sp. on the basis of hyphal characteristics and nuclei number. They were tested for detection of the anastomosis group, optimum growth temperature, rDNA-ITS region traits and pathogenicity on miniature rose in vivo and in vitro. The analysis of hyphal reaction anastomosis was carried out with the tester isolates of binucleate Rhizoctonia AG-A, AG-Ba, AG-G as well as multinucleate Rhizoctonia AG2-2IIB and AG4-HGI already detected on miniature rose. The optimum temperature for growth of binucleate Rhizoctonia sp. was 35oC. In in vivo test, the symptoms of root rot were observed 35 days after inoculation and mortality happened two weeks later. According to molecular and anastomosis test groups, our results showed that all the isolates have the maximum similarity to AG-G. This is the first report of anastomosis group G (AG-G) of binucleate Rhizoctonia sp., the causal agent of root rot disease on miniature roses in Iran.

Fungi produce a wide range of secondary metabolites such as antibiotics, toxins, alkaloids, fatty acids, ketones and alcohols during active cell growth. The present study aimed to identify the secondary metabolites from some Penicillium species, using GC-MS. Many important compounds such as 3-oxoq- uinuclidine in Penicillium jenseii, formamidine in Penicillium pusillum, orcinol and 1,3,8-p-menthatriene in Penicillium canescens and limonene in Penicillium purpurogenum were identified. Moreover, fatty acids and hydrocarbons were produced by all the tested species.

Pleosporaceae is an important Dothideomycetes family. To elucidate relationships among some selected anamorphic pleosporalean taxa, their Internal Transcribed Spacer (ITS) and RNA polymerase second largest subunit (RPB2) were sequenced and compared. Phylogenetic analyses of both ITS and RPB2 regions were almost similar and generally congruent with previously described phylogenies and morphology based classification schemes. ITS was inefficient to show the taxonomic placement of some species, especially Alternaria species; but RPB2 was appropriate for this purpose.