شناسایی عوامل قارچی بیماری پوسیدگی ریشه و طوقه گوجهفرنگی در استان هرمزگان.

Root and crown rot is a common tomato disease in the major production areas of Hormozgan province. The present study was conducted to isolate, identify, and determine the frequency of fungal agents associated with tomato root and crown rot in Hormozgan province. In total, 984 fungal isolates were obtained from tomato plants with yellowing, wilting, and root and crown rot symptoms. Identification of the isolates was done based on the morphological characteristics and the comparison of the obtained sequences of the ribosomal internal transcribed spacer region (ITS-rDNA) and parts of the translation elongation factor-1 alpha (tef1-α) gene with relevant sequences available in GenBank. According to the results, the highest frequency belonged to Fusarium oxysporum isolates (73%), and afterward to Rhizoctonia solani and F. acutatum species with eight and one percent frequencies, respectively. The results of the pathogenicity tests of the fungal species on tomato seedlings hybrid Sunseed 6189 at the stage of four true-leaves revealed that all three species were pathogenic on tomato seedlings and caused root and crown rot, yellowing, and death of the plant aerial tissues. Pathogenic isolates of F. oxysporum were identified as F. oxysporum f. sp. radicis-lycopersici using sprl-specific primers. To the best of our knowledge, this is the first report of F. oxysporum f. sp. radicis-lycopersici on tomato in Hormozgan province, and the first report of F. acutatum as tomato root and crown rot agent in the world. [ABSTRACT FROM AUTHOR]