ABSTRACT
Morphological, cultural and physiological characteristics of 19 Helminthosporium-like hyphomycetes isolated from the White Sea were studied. Taxonomic status of the isolates was verified using molecular genetics techniques. One of the isolates was identified as Alternatia sp., while the rest of marine isolates belonged to the species Paradendriphiella salina (G.K. Sutherl.) Woudenb. & Crous. The specific features of the isolates studied were characterized as adaptive. Optimum salinity for their growth was 1-2% NaCl, which is lower than the value for the known open ocean isolates. This is probably due to relatively low salinity of White Sea (22-24 per thousand) as compared with the ocean water (35 per thousand). While the temperature optimum for growth was 22 per thousand, growth and sporulation occurred at 6 degrees C, which has not been reported for marine fungi isolated from warmer seawater. All isolates studied grew and sporulated efficiently on the medium supplied with the Fucus algae extract and in the sea water layer. Conidia of the isolates submerged in the sea water were propagated efficiently, unlike the soil-born fungi. Holoblastic conidiogenesis was demonstrated by light and scanning electron microscopy, confirming the separation of P. salina from the genus Scolecobasidium.
Subject(s)
Helminthosporium/classification , Helminthosporium/growth & development , Phylogeny , RNA, Ribosomal, 16S/genetics , Water Microbiology , Aquatic Organisms , Helminthosporium/drug effects , Helminthosporium/genetics , Salinity , Salt Tolerance/physiology , Sodium Chloride/pharmacology , TemperatureABSTRACT
A new fungal isolate that grows endophytically in sweet sorghum was identified as Helminthosporium velutinum Link ex Ficinus & Schubert. Light-microscopy of cross-sections of colonized sweet sorghum roots showed that the intercellular, pigmented hyphae of the fungus was mostly limited to the epidermal layer and formed outer mantle-like structures. This endophyte has the ability to significantly increase sweet sorghum biomass. This is the first report of Helminthosporium as an endophyte and could help realize sustainable the biomass production for biofuel purposes.