Identification and evaluation of the inhibitory effect of endophytic fungi of red onion against some onion pathogens

In order to identify the endophytic fungi of Azarshahr red onion variety, sampling was conducted from the main cultivation areas of this plant in East Azarbaijan province. A total of 360 fungal isolates were obtained from different parts of onion (root, base, scale, flowering stem and leaf). The isolates were grouped based on their phenotypic characteristics on culture media and comparing the DNA fingerprinting patterns using the ISSR molecular markers. In order to accurate identification of the endophytic fungi, the morphological characteristics were combined with the phylogeny inferred from analysis of ITS-rDNA genomic region sequence. Examined endophyte isolates were belonged into eight genera and 12 species namely Alternaria atrum, A. tenuissima, Aspergillus niger, A. kevei, Fusarium equiseti, F. oxysporum, F. proliferatum, F. solani, Mortierella alpina, Setophoma terrestris, Stachybotrys chartarum and Trichoderma longibrachiatum. The results of the inhibitory effect experiments of the selected endophyte Trichoderma longibrachiatum strain ASh268 on the growth of several pathogenic fungal isolates including Rhizoctonia solani, Fusarium oxysporum, Fusarium solani and Setophoma terrestris showed that this strain has a good ability to produce cellulase enzyme in carboxymethyl cellulose medium and significantly reduces the growth of all the above pathogens on the culture media. To our knowledge, this is the first report of Aspergillus kevei for the funga of Iran. Also, this research is the first study on the isolation and identification of endophytic fungi of red onion verity in its major cultivation areas in Iran.