![]() The pathogenicity test was performed twice with the same result. All the inoculated plants of both varieties developed characteristic symptoms of the disease 7 days after inoculation, while the control plants remained symptomless. Twelve plants were left uninoculated as controls. Plants were inoculated with the FAVF654 isolate by applying three sclerotia at the base of each of the 12 plants. Pathogenicity of the fungus was demonstrated by inoculating healthy sesame plants (Dormilón and SOPC-9539 TD varieties) germinated in plastic pots with sterile substrate. BLASTn alignments in GenBank showed 100% identity of our sequence with the sequence of the type strain of Sclerotinia sclerotiorum ATCC 46762 (accession no. The resulting consensus sequence was deposited in GenBank (accession no. To confirm identification, genomic DNA was extracted from one isolate, and the internal transcribed spacer (ITS) region was amplified by PCR and sequenced directly using the primer pair ITS5/ITS4 ( White et al. One isolate was deposited in the Culture Collection of Phytopathogenic Fungi of the Faculty of Agriculture of Fuerte Valley at the Sinaloa Autonomous University under accession no. Sclerotia averaged 3.1 mm in diameter and 0.024 g. Fungal colonies were formed of compact white mycelium, with the formation of sclerotia on the margin of the plate 6 days after inoculating PDA cultures. Sclerotinia-like colonies were consistently isolated and four isolates from different locations were purified by the hyphal-tip method. The plates were incubated at 28☌ in darkness for 48 h. The tissue sections were dried on sterile blotting paper and plated in Petri dishes with potato dextrose agar (PDA) culture medium. For fungal isolation, stem sections from the symptomatic basal stem were surface disinfected with 1.5% sodium hypochlorite for 2 min and triple rinsed with sterile distilled water. Disease incidence was estimated at 15% by five counts of diseased plants in arbitrary quadrants in the sesame fields. Infected plants showed symptoms of yellowing, wilting, and finally death. At advanced stages of the disease, the circumference of the stem was necrotic with white mycelium extending to the roots. Initially, small brown spots in the basal stem of infected plants were observed. In October 2020, collar rot symptoms were observed in six sesame fields (SOPC-9539 TD variety) in the Carrizo Valley (26☁5′33.1″N 109☀1′37.9″W), El Fuerte, Sinaloa, México. The seeds of this crop are used as a condiment, for the extraction of oil, and for their medicinal properties. ![]() Pedaliaceae) is the second most cultivated oilseed in Mexico with 80,000 ha planted per year.
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