MOLECULAR CHARACTERIZATION OF Sclerotium rolfsii Sacc. INCITING STEMROT OF GROUNDNUT PLANT (Arachis hypogea L.)

Abstract

In the present study, stem rot disease of groundnut was observed in many crop fields of Telangana, India during survey. The most distinguishable symptom is a white fan shaped abundant fungal mycelium mat that appears on the soil surface, leaf fragments and at stem bases of infected plants. The mycelial mat may be seen on the stem a few millimeters above the soil line. Abundant mustard seed-sized, brown to dark brown, spherical sclerotia, initially white later turned to dark brown on maturation was recorded. The fungal pathogen was isolated on potato dextrose agar (PDA) medium. Genomic DNA was isolated and internal transcribed region of ribosomal DNA was amplified using ITS1 universal primers. Based on cultural, morphological and molecular characteristics, the fungal pathogen was identified as Sclerotium rolfsii. The rDNA sequence results also showed 98% similarity with reference sequence OR911599 and JF966208.1 confirming pathogen identity. The pathogenicity test was conducted on
healthy plants for symptom expression after 6-8 days of inoculation. S. rolfsii is known to infect many economically important crop plants at various stages of its growth and development.