Keywords: Cuminum cyminum L., Fusarium oxysporum f. sp. cumini (Foc), Genetic variability, Polymorphism, Pathogenicity, Species specificity
The fungal pathogen, Fusarium oxysporum f. sp. cumini (Foc) (soil born organism) is a severe menace to cumin cultivation in India and leads up to 80% of yield loss depending on disease severity. The present study was aimed to evaluate the diversities and similarities between isolates originating from different agro-climatic environments and to analyze pathogenicity in cumin plants. This study investigated a total of thirteen isolates of Fusarium oxysporum f. sp. cumini collected from different areas of Gujarat and Rajasthan. These isolates were screened and differentiated based on morphological characteristics such as colony character, color, pigmentation, and sporulation. Mycelial growth pattern showed discrimination among all isolates. The infestation rate of fungi on plants was diverse when analyzed with total proteins and activity of defense-related enzymes such as peroxidase, polyphenol oxidase, and catalase. They varied in pathogenicity when tested on var. GC-2 (susceptible variety). Junagadh isolate (I4) was found to be highly virulent amongst all. Genetic variability among the isolates was assessed using RAPD markers, a total of 693 loci were produced, out of which 651 were polymorphic with 93.99% average polymorphism. The species specificity was marked using internal transcribed spacer (ITS) primers with product amplification of approx. 437.24 bp in all the isolates. Overall, the results suggested that a high genetic variability and heterogeneity in Fusarium isolates call for the urge of gene identification from resistant cultivar and employ them in developing resistance breeding program combating the Fusarium oxysporum in cumin.
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The financial assistance provided by AAU, Anand is greatly acknowledged. We are also thankful to the departments of Tissue Culture, Biochemistry and Plant Pathology for assistance in various ways.