MYCOLOGIA IRANICA
Year:2016 | Volume:3 | Issue:1 |Papers Count:7

Colletotrichum species are associated with citrus plants as pathogens, saprobes and endophytes. According to the most recent multigene phylogenetic analysis, a lot of changes were happened in the taxonomy and species delimitation in the genus Colletotrichum. In this investigation, 292 Colletotrichum isolates were obtained from leaves, fruits and stems of Citrus species at Golestan, Mazandaran, Guilan and Kerman provinces. After morphological studies, a multilocus molecular phylogenetic analysis (TUB2, CHS -1, CAL) of 13 isolates were carried out. Based on the morphological and molecular data, five species including C. gloeosporioides s. s., C. fructicola and C. siamense (from C. gloeosporioides s. l.); C. karstii and C. novae zelandiae (from C. boninense s. l.) were identified. According to our knowledge, this is the first report of C. novae–zelandiae from Iran and C. siamense and C. karstii from citrus plants in the country.

Evidence for the role of chitinases in biocontrol by Trichoderma species has been well documented.Chit42 lacks a chitin–binding domain (ChBD) which is involved in its binding activity to insoluble chitin. The objective of the present study was to enhance antifungal activity of T. harzianum by overexpression of wild type and hybrid forms of Chit42 containing chitin binding domain. To produce chimeric chitinase with improved enzyme activity, the hybrid chitinase was constructed by the adding of ChBD from Rhizopus oligosporus to the C-terminal end of Chit42 cDNA from T. atroviride using SoEing PCR. The recombinant hybrid chitinase (Chit42-ChBD) displayed a 1.56 fold higher chitinase activity than Chit42. This increase suggests that the ChBDmay play a role in helping the enzyme to bind better to the insoluble chitin. Moreover, Chit42-ChBD transformants showed higher antifungal activity towards Fusarium graminearum, the causal agent of Fusarium head blight (FHB) disease in wheat.

Some fungal species were isolated from scab or scab-like symptoms on leaves of various plant hosts in Iran. Some of them isolated from apple and pear leaves were investigated in the present study. The isolates were identified based on the morphological and cultural characteristics. On the other hand, for molecular identification and phylogenetic analyses were carried out based on the sequence of ITS-rDNA region (including 5.8S rDNA). As a result, six species, namely Acremonium fusidioides, Acrostalagmus luteoalbus, Clonostachys rosea, Sarocladium kiliense, Sarocladium strictum and Endoconidioma populi were identified. Among them, Acremonium fusidioides is a new taxon for the mycobiota of Iran.

In the present study, pathogenicity of four native strains of entomopathogenic fungus; Metarhizium anisopliae, was studied against adult stage of Ixodes ricinus. For this purpose a total number of 180 adult ticks were examined in triplicate. Thirty ticks for each strain and negative and positive controls were immersed in 2.4 × 107 fungal conidia/ml in vitro. Samples were incubated in separate Petri dishes at 26 oC and 70% relative humidity. Positive control groups were treated with Cypermethrin and negative controls were immersed in the same volume of sterilized distilled water. Mortality rate and fungal grow on ticks for each strain were reported in comparison with control groups. M. anisopliae IRAN 437 C showed the highest virulence in mortality and mycelium grow on ticks. Cypermethrin killed the ticks with higher potency than that of entomopathogenic fungi. Scanning electron microscopy showed the growth of M. anisopliae on the surface of tick bodies and penetration of fungal hyphae through tick cuticle. Taken together, results obtained from this study show potential of Iranian Entomopathogenic fungi as a biocontrol agents of I. ricinus. This is the first report demonstrates the mechanism of action of entomopathogenic fungi of the genus Metarhizium on ticks at electron microscopy level.

Fungi release wide spectrum of volatile organic compounds (VOCs) that belong to several chemical groups with different biochemical origins such as monoterpenes, sesquiterpenes, alcohols, aldehydes, aromatic compounds, esters, furans, ketones, sulfur and nitrogen compounds. Trichoderma species are the most studied fungal biocontrol agents and are successfully used as biofungicides and biofertilizers in greenhouse and field. Volatile metabolites play a key role in mycoparasitism of Trichoderma spp., as well as in their interactions with plants and other organisms in their environments. Based on the antibiotic activity of these fungi against the fungal pathogens, further consideration of their VOCs profiles, has been offered. In this study, VOCs of native Trichoderma species from Iran (T. harzianum, T. virens (6011), T. atroviridae (1-3)) have been identified by static headspace gas chromatography-mass spectrometry The most of detected compounds were related to monoterpenes and sesquiterpenes. These are including; dl-limonene; beta-himachalene; beta-cubebene; cadinene; caryophyllene; alpha-gurjunene; farnesol; thujopsene; beta-bisabolene and alpha-farnesene. Based on antifungal effects of these compounds, biological control of these Trichoderma species can be related to them. These VOCs could be potential sources for purposes of chemotaxonomy and natural fungicides to protect crops from the fungal pathogens without environmental problems.

White-rot basidiomycetes are one of the most important lignolytic microorganisms. These fungi have been reported to secrete three main classes of lignin degrading enzymes: lignin peroxidases (LiPs), manganese peroxidases (MnPs) and laccases. In this study, for the first time the lignin degrading capability of two plant pathogens i.e. Hyphodermella rosae and H. corrugata was evaluated using both biochemical and molecular methods. Biochemical analyses included tannic acid, azur-B clearance, 2, 2' -azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), α-naphthol and Syringaldazine test. Genes encoding for each enzyme were amplified using two pairs of degenerate primers. In the case of MnP, the primers from the previous studies failed to amplify the gene for Hyphodermella as well as control species, hence new primers were designed. The results from biochemical and molecular analyses confirmed the potential of both the Hyphodermella species to produce LiPs and MnPs, whereas they tested negative in terms of laccase production. Similar to the model white-rot fungus, Phanerochaete chrysosporium, laccase production may not be required for lignin decomposition by the Hyphodermella species treated in this study.

The disposed wastes of zinc industries contain large amounts of heavy metals such as Pb2+ and Cd2+. These elements are considered as hazardous elements to human beings and other organisms. This study aims at introducing the fungal isolates that evolved to be compatible with waste deposits during the time and can absorb Pb2+ and Cd2+ ions. During the spring and autumn in 2011, eight samples of sediment contaminated by waste were collected from Zanjan zinc industrial zone and fungal isolates were isolated. The degree of tolerance against 0–2500 mg/L Pb2+ and Cd2 was measured using minimum inhibitory concentration (MIC) experiment. Results revealed that two Aspergillus sp. isolates namely A.BZ1 isolated in spring and A.PZ1 isolated in the autumn showed the highest resistance and the maximum growth rate. The result of sorption capacity by live and dead biomasses of two isolates against Pb2+ and Cd2+ ions with different metal concentrations showed the highest uptake by living biomass of A.PZ1 with 53.75 mg/g and 7.02 mg/g and minimum adsorption in dead biomass was 3.65 and 0.19 mg/g. The results of contact time on isolates sorption revealed that A.PZ1 with 1.715 mg/g sorption has 72.97 % removal efficiency in the first 30 minutes. After the identification of these two isolates and the combination of morphological criteria and sequencing of the ITS˗rDNA region, the A. fumigatus was identified. The prevalence of isolate population, metal tolerance and the genome information in fungi are three traits that can be used as biomarkers for monitoring contaminants in the environment.