Isolation, Molecular Identification, and Mycotoxin Production of Aspergillus Species Isolated from the Rhizosphere of Sugarcane in the South of Iran

Knowledge of the genetic diversity detected among fungal species belonging to the genusAspergillus is of key importance for explaining their important ecological role in the environmentand agriculture. The current study aimed to identify Aspergillus species occurring in the rhizosphereof sugarcane in the South of Iran, and to investigate their mycotoxin profiles. One-hundred andtwenty-five Aspergillus strains were isolated from the soil of eight major sugarcane-producing sites,and were molecularly identified using sequences of partial -tubulin (benA) and partial calmodulin(CaM) genes. Our molecular and phylogenetic results showed that around 70% of strains belongedto the Aspergillus section Nigri, and around 25% of species belonged to the Aspergillus section Terrei.Species belonging to both sections are able to produce dierent mycotoxins. The production ofmycotoxins was measured for each species, according to their known mycotoxin profile: patulin (PAT)and sterigmatocystin (STG) for Aspergillus terreus; ochratoxin A (OTA) and fumonisins for Aspergilluswelwitschiae; and OTA alone for Aspergillus tubingensis. The data showed that the production ofOTA was detected in only 4 out of 10 strains of A. welwitschiae, while none of the A. tubingensisstrains analyzed produced the mycotoxin. Fumonisins were produced by 8 out of 10 strains ofA. welwitschiae. Finally, none of the 23 strains of A. terreus produced STG, while 13 of them producedPAT. The occurrence of such mycotoxigenic plant pathogens among the fungal community occurringin soil of sugarcane fields may represent a significant source of inoculum for the possible colonizationof sugarcane plants, since the early stages of plant growth, due to the mycotoxin production capability,could have worrisome implications in terms of both the safety and loss of products at harvest.