Abstract
In September 2014, leaf blight was observed on hyacinth bean [Lablab purpureus (L.) Sweet] in West Bengal, India, with a disease incidence of 5–20%. Symptoms included leaf discoloration with velvety sporulation of the pathogen on the leaf. Isolation of the pathogen was done by placing small pieces (5×5 mm) of infected tissue, disinfected with 1% NaOCl for 1 min, onto potato dextrose agar (PDA), and kept for 48 h at 28±2°C. Based on the multispored sporangia (38-104 µm) and sporangiospores measuring 12.5-20 × 5-12.4 µm, the fungus was identified as Choanephora cucurbitarum (Kirk, 1984). Specimens were deposited in collections in ARI, Pune, India, with infected plant tissue in AMH (accession 9820), and isolate L.P-12 in NFCCI (accession 4007). Molecular identification was done by amplifying the ITS region of nuclear DNA using ITS1 and ITS4 primers (White, 1990). The ITS region is appropriate barcoding marker in Mucorales (Walther et al., 2013). A BLAST search revealed the sequence from isolate L.P-12 (KU886142) had 99% identity with JN206234 (CBS 445.72). A pathogenicity test was conducted by spraying of spore suspension (1x106 spores/ml) on 5 detached leaves with three replications. Both inoculated and control (water sprayed) plants were kept in a humid chamber at 28±2°C. Water soaked necrotic lesions developed within 96-120 h and typical blight symptoms and emerging sporangiola were observed 8-10 days after inoculation. This is the first report of leaf blight disease of hyacinth bean [Lablab purpureus (L.) Sweet] caused by Choanephora cucurbitarum in India.
Published Version
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