Isolation and Pathogenicity Test of Fusarium Basal Rot and Purple Blotch Fungal Pathogens from Shallot and Allium spp.
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Date
2022-01-19
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Balai Besar Penelitian dan Pengembangan Bioteknologi dan Sumber Daya Genetik Pertanian
Abstract
Abstract. Fusarium basal rot and purple blotch are dominant fungal diseases of Allium spp. As a part of mutation breeding project to develop resistant shallot varieties to the fungal agents, this study was aimed to isolate and test the pathogenicity of the isolated fungi. Fungal isolation was performed by means of standard tissue isolation technique from diseased samples collected from six shallot and scallion fields in West Java. Three isolates of Fusarium and four isolates of Alternaria porri were obtained from the respective disease symptom. Additionally, Stemphylium sp. was recovered from leaf blight symptom and A. alternata from both diseased leaf symptoms. Koch’s Postulate was accomplished by pathogenicity tests and reisolation of the fungi. A modified onion bulb assay resulted in mild to extensive rot of bulbs inoculated with Fusarium agar plugs. Pot assay confirmed the aggressiveness of Fusarium isolates to shallot varieties. Allium spp. plants developed purple blotch after sprayed with A. porri spores, and leaf blight after sprayed with
Stemphylium sp. or A. alternata spores. Except for A. alternata, all pathogens were successfully reisolated from the foliage disease symptoms, confirming their causative agents of the respective disease. For future genetic studies and species confirmation by means of DNA sequencing, single spore isolation of the pathogens should be attempted.
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Keywords
Breeding, fungal diseases, Isolation