reza mostowfizadeh

Pythium oligandrum is known as an important biological agent against plant pathogens. Isolates from different regions of Iran including Bushehr, Bakhtiari, Chaharmahal, Fars, Golestan, Ilam, Kermanshah, Kerman, West Azerbaijan and Yazd were identified based on morphological and molecular characteristics. The highest recovering frequency of isolates was observed in Kermanshah and Fars provinces. The functional diversity of isolates based on their growth temperature and biological control effect under laboratory conditions was evaluated. The antagonistic effects of native P. oligandrum isolates were evaluated against soil–borne fungal pathogens including Rhizoctonia solani, Phytophthora parasitica, Fusarium solani, F. oxysporum f. sp. lycopersici and F. oxysporum f. sp. pisi using nonparametric statistics, and compered with commercial products of various biocontrol agents such as Clonostachys rosea, Fusarium oxysporum, P. oligandrum and Trichoderma spp. The native isolates of P. oligandrum were diverse in their growth temperature and biocontrol activities. The highest mycelial growth inhibition was found in the interaction between P. oligandrum isolates and R. solani. A significant difference between P. oligandrum isolates was found by evaluating their volatile compounds. The isolates of P. oligandrum showed maximum inhibition on P. parasitica and R. solani and minimum inhibition on F. oxysporum f. sp. lycopersici. The non–volatile compounds had the highest significant effect on P. parasitica as well. The result of this study showed that the growth characteristics and the in vitro biocontrol ability of the native isolates of P. oligandrum on various plant pathogens were different. This variety can be employed in biochemical and greenhouse screening of the isolates.

Essential oils are hydrophobic, volatile and aromatic compounds that have been used as fragrances and flavors for a long time. Recent studies have shown that some plant essential oils have fungicidal effects against some important plant pathogens. For instance, the essential oil of thyme inhibits the mycelial growth of Penicillium italicum and the essential oil of lavender shows the fungistatic effect on ‎ Botrytis cinerea, Rhizopus stolonifer and Aspergillus niger. The essential oil of thyme has also been used to control the black rot of orange caused by Alternaria citri and grey mold of strawberry fruits caused by Botrytis cinerea. Antifungal activities of essential oils are mainly related to their effects on fungal cell wall, cell membrane, mitochondria and nitric oxide level. As a result of increased concern about harmful chemical pesticides, essential oils can have a good place in the market as natural fungicides. In this paper, application of essential oils as natural fungicides, their mode of actions and some safety aspects of their application have been discussed.

During last decade, the decline of elm trees was observed in Fars province (Iran) due to a wood decaying agent in heartwood of the trees. Unknown basidiomycete isolates were frequently isolated from such trees. The objective of the present study was to identify the basidiomycete isolates by molecular phylogenetic analysis of the internal transcribed spacers of ribosomal DNA. For this purpose, isolates of a basidiomycete were recovered from infected elm trees with brown rot in heartwood in Fars province. The isolates developed buff-colored colonies with white margins which produced red-brownish pigments in both PDA and MEA media. Mycelial width was average 2.4–3.8 µm, with brown cell wall without clamp connections. No aerial mycelia were observed in any isolates and average growth rate of colonies was 1.35mm-1 at 25 °C. No sexual organs were observed after six months of incubation at 25°C. Neighbor-joining phylogenetic analysis of internal transcribed spacers of rDNA (ITS) of sequences showed that the isolates belong to Fomitiporia mediterranea. This is the first report of F. mediterranea for Iran mycobiota. Small pieces of decaying wood from infected elm trees were placed on PDA and MEA at 25 °C and recovered isolates were purified on WA by hyphal tip method. Isolates were grown in 50 ml still culture of potato broth at 25 ºC. Freeze-dried mycelia were homogenized using sea sand (Fluka, Germany) and a plastic disposable pestle. Freeze-dried plant materials were also homogenized using mortars and pestles. DNA was extracted from homogenized preparation using a Genomic DNA Purification kit, (Fermentas, UK) according to the manufacturer’s instructions. DNA of the internal transcribed spacer regions (ITS) were amplified using the universal primers ITS1:5'- TCC GTA GGT GAA CCT GCG G -3' and ITS4:5'- TCC TCC GCT TAT TGA TAT GC -3'. Amplifications were performed in a CG1-96 thermocycler (Korbett Research, Australia). The PCR mixture contained: 10–20 ng of template DNA, 1 μM of each primer, 100 μM of dNTPs, 0.4 U Taq DNApolymerase (CinnaGen, Iran), 1.5 mM of Mg Cl2, 2.5 μl of 10× PCR buffer, 100 mM BSA, in a reaction volume of 25 μl. All PCRs consisted of 1 cycle of 94 °C for 3 min; 30 cycles of 95 °C for 30 s, 50 °C for 30 s, 72 °C for 60 s; and a final cycle of 72 °C for 10 min. PCR products were sequenced. Sequences of the internal transcribed spacer regions including the 5.8S gene of rDNA were used to study phylogenetic relationships of the studied taxa. The internal transcribed spacers sequences of rDNA generated in this study were compared to those of other taxa obtained from GenBank. A preliminary alignment of sequences was made using ClustalX with subsequent visual adjustment. Neighbor-joining phylogenetic analysis of internal transcribed spacers of rDNA (ITS) of sequences showed that the isolates belong to Fomitiporia mediterranea M. Fisch. (Fig. 1). The 780 bp sequence of isolate EN1 (GenBank Accession No.: HM582097) was 99% similar to ITS sequence from fruit body of F. mediterranea (Pilotti et al. 2005, GenBank Accession No.: AY620997) with some differences in 260 (T to C substitution) and 774 (A to gap substitution) nucleotide sites. Fomitiporia mediterranea was distinct by the sequences of the ribosomal DNA (ITS) region and growth rates at temperatures between 15 °C and 35 °C (Elena et al. 2006). The isolates developed buff colored colonies with white margins which produced red-brownish pigments in both PDA and MEA media (Fig. 2). Average mycelia width was 2.4–3.8 µm, with brown cell wall without clamp connections. No aerial mycelia were observed in any isolates and average growth rate of colonies was 1.35mm d-1 at 25 °C. No sexual organs were observed after six months of incubation at 25 °C. The isolates were able to grow at all temperatures tested between 15 °C and 35 °C. This is the first report of F. mediterranea for Iran.
Specimen examined: Iran: Fars province, Shiraz, Bajgah, isolate EN1, recovered from elm trees, deposited at the Fungal Culture Collection of the Department of Plant Protection, Shiraz University, Shiraz, Iran (FT01.15.01).

Summary
During 2016–17, 277 samples of leaf compost, manure, virgin and rhizosphere soil of some plants from Fars and Khuzestan provinces (Iran) were transferred to Mycology Laboratory of the Department of Plant Protection, Shiraz
University (Iran). Fungi were recovered by soil plate and soil dilution methods. After purification, the isolates of Mucorales were identified based on growth, morphological and microscopic characteristics. Absidia cylinderospora,
A. pseudocylinderospora, and Cunninghamella echinulata var. indica were new to Iran mycobiota.

Pink rot, caused by Phytophthora erythroseptica, is an important soil-borne disease of potato causes significant losses in the field and storage. A selection of P. erythroseptica isolates from potato-growing regions in four continents including America, Asia, Europe and Australia was assessed using phylogenetic, morphological and physiological analyses. In all nuclear (internal transcribed spacers, ß-tubulin and heat shock protein 90) and mitochondrial (cytochrome c oxidase subunit I) trees as well as combined nuclear and mitochondrial tree, P. erythroseptica isolates formed a separate phylogenetic lineage containing the type isolate. Additionally, no morphological and physiological diversities were observed among the isolates. All isolates were homothallic and produced amphigynous terminal antheridia and globose aplerotic oogonia as well as non-papillate and ellipsoid to ovoid sporangia. The results showed that P. erythroseptica isolates belonged to different geographic regions are phylogenetically and morphologically similar. This uniformity could be due to the homothallic nature of P. erythroseptica or distribution of a single clone of pathogen by infected potato.

Infected tissues of roots and leaves of various grasses as well as soil around their rhizosphere were sampled from Fars, Golestan, Isfahan, Khorasan Shomali, Khorasan Razavi, Mazandaran and Semnan provinces (Iran). Based on morphological characteristics and available keys, four species of Bipolaris including B. austreliensis, B. indica, B. micropus and B. spicifera, four species of Curvularia including C. akaiiensis, C. heteropogonicola, C. protuberata and C. verruculosa and two species of Exserhilum including E. gedarefense and E. pedicellatum were identified. Bipolaris austreliensis and B. spicifera widely distributed in Iran. Bipolaris micropus, C. protuberata, C. akaiiensis, E. pedicellatum and E. gedarefense are new to Iran mycobiota.

Accurate identification of fungi and fungus-like organisms is one of the most important steps for finding an approach to employ or control them. Nevertheless, this process is usually laborious and slow. Application of interactive keys is one of the ways to save the time and have an accurate identification of the species. An interactive key is a computer program in which the user enters morphological or molecular attributes of the specimen and the program compares them with the data of its database to find a match species with the highest similarity. Such keys also allocate separate images and other data for any known species. In this paper some of the interactive identification keys and their function is discussed.

Phytoplasmas are some plant pathogens that establish and propagate in plant phloems. They have transmitted by sucking insects. Phytoplasmas have a different lifecycle as compare to bacterial pathogens. They have ability to infect different hosts two different kingdoms, planta and animalia (insects). They systemically infect their hosts. Phytoplasmas have various approaches for adaptation to their hosts. Some of adaptation mechanisms include: changes in the level of gene expression, variation and recombination in extrachromosomal DNA and potential mobile units, production of effectors and suppression of defense signaling pathways. These approaches enable them to establish, propagate and infect various hosts. Recognizing these strategies would be a major step on the effective management of these pathogens.

The importance of plant protection is increasing with the need of optimizing the quality of agricultural yields. This is essential to search for suitable and appropriate microorganisms for biological control and also study and practice on how to use the optimal conditions for the successful management of plant diseases. One of these microorganisms is the fungus-like, Pythium oligandrum that live saprophytic in the soil. This microorganism has antagonistic and hyper parasitic effects on some of soil borne pathogens. This is not virulent on the 12 species of plants, belonging to six families and only present on their root surface. It is used for control of the wide range of pathogens of the field crops and also can stimulate plant growth, result in increasing the yield.