MORPHO-MOLECULAR IDENTIFICATION OF POTATO SILVER SCURF CAUSED BY HELMINTHOSPORIUM SOLANI AND STANDARDIZATION OF SPORE INUNDATION TECHNIQUE

Abstract

Potato is considered as a future crop to secure food security in developing nations. Of many storage diseases
that impede the trade value of potatoes, silver scurf is steadily rising. The causal fungus Helminthosporium solani, belongs
to Ascomycetes group and it attacks the potato tubers in the field as well as in storage. During the year 2019 the tuber
samples were obtained from cold stores of Madhya Pradesh which were symptomatic to silver scurf disease. The appearance
of tuber comprised of silvery skin blemishes on the periderm of tubers. The inundation of spores was standardized from
the silvery lesions by incubation of infected tubers at different temperatures (12, 18, 24 °C). The spores were observed
in the form of whorls on the tuber surface and these whorls were also visualized in compound microscope using double
adhesive tape method. The pure culture of fungus produced initial hyaline mycelium which turned blackish brown after
21 days. The fungus was observed as extremely slow in its growth. The conidiophores were septate having a thin apex
and broader base and melanized conidia were observed in a basipetal succession. The conidia were recorded to have two
to eight pseudosepta. The molecular identification of fungus was performed through internal transcribed region based
universal primers. The obtained sequences were submitted to the NCBI GenBank. An attention towards the pathogenomics,
infection process and management strategies of silver scurf disease is mandatory to strengthen the processing industries
involved in potato production system worldwide.