Genetic variabilities and relationships among some egyptian Aspergillus spp. based on microscopic characters, isozyme profiles and random amplification of polymorphic DNA

Twelve Aspergillus spp. were isolated from the Egyptian soils and were studied morphologically and microscopically. Isozyme profiles and random amplified polymorphic DNA (RAPD) were also employed for determination of the genetic relationship among the tested Aspergillus spp. Results of RAPD revealed genetic similarity level above 80% between A. terreus and A. aculeatus. The species A. niger, A. candidus, A. terreus and A. aculeatus were joined with a similarity level of 65%. Unique bands were displayed by certain fungi and can be taken as a positive marker for isolate identification. Five isozyme systems; peroxidase, alcohol dehydrogenase, α esterase, β esterase and superoxide dismutase were studied to detect the genetic variabilities among the tested isolates. Subsequently, comparing the three dendrograms which belong to morphological characters, isoymes and RAPD revealed a great relationship between A. terreus and A. niveus from one side and A. candidus and A. terreus from the other side.

Preliminary study of endophytic fungi in timothy (Phleum pratense) in Estonia

Timothy (<em>Phleum pratense </em>L.) is an important agricultural grass in Europe and North America, but there is little research into the occurrence and abundance of fungal endophyte species associated with this grass. The aim of this study was to identify fungal endophytes living within <em>P. </em>pratense and to determine if additional moisture applied during the growing season increases the diversity of endophytic fungi. We studied 58 isolates obtained from surface-sterilised blades of 60 <em>P. pratense </em>plants collected from Rõka Free Air Humidity Manipulation experimental plots (FAHM), Estonia. Morphological and molecular methods were used for isolate identification. As a result, 45 strains from 10 different taxa were identified, all belonging to Ascomycota. Five species were found to be new to <em>P. pratense</em>.

SXT-Related Integrating Conjugative Element in New World Vibrio cholerae

ABSTRACT SXT-related integrating conjugative elements (ICEs) became prevalent in Asian Vibrio cholerae populations after V. cholerae O139 emerged. Here, we describe an SXT-related ICE, ICEVchMex1, in a Mexican environmental V. cholerae isolate. Identification of ICEVchMex1 represents the first description of an SXT-related ICE in the Western Hemisphere. The significant differences between the SXT and ICEVchMex1 genomes suggest that these ICEs have evolved independently.

First Report of Rhizoctonia solani AG-7 on Cotton in Mississippi

During a field study of the soilborne mycobiota on cotton (Gossypium hirsutum L.) roots, Rhizoctonia solani Kühn AG-7 was isolated from dark brown lesions present on the tap, feeder, and secondary roots onto potato-dextrose agar (PDA) (34 g of medium per liter of distilled water). Isolate identification was confirmed using tester R. solani AG-7 isolates (Carling, University of Alaska) for comparison during anastomosis pairing. To confirm pathogenicity, six AG-7 isolates (65, 66, 67, 68, 69, 70) obtained from cotton roots were tested in a plant growth incubator (18–24°C) by mixing 2.5 ml of 2-week-old cornmeal sand inoculum (3 g cornmeal, 100 g sand, and 20 ml distilled water) with 500 ml of autoclaved soil into each of five replicate polystyrene pots (15 cm wide × 20 cm long) per isolate. Five control pots containing noninfested soil were added for comparison. Five seed of cv. Deltapine 50 were sown into each pot. For all six isolates, mean stand counts (ranging from 0 and 1.3 plants per pot) were significantly lower (P ≤ 0.05) compared with those of plants in noninfested pots (3.8 plants per pot) at 21 days after planting. Furthermore, when the roots of surviving seedlings were evaluated for disease severity, brown, discolored lesions were observed at the base of stems and on roots in infested pots for all six isolates. Six AG-7 cultures of the pathogen were reisolated from symptomatic tissues onto PDA. The experiment was repeated with similar results. This is the first report of AG-7 occurring in Mississippi.