Isolation and molecular identification of fungi that cause stem rot disease in Bali's local legumes

Abstract

Efforts to improve food security in Indonesia, especially in Bali, need to be supported by improvements in cultivation techniques, including the management of pests and diseases. Legume crops are often attacked by stem rot diseases which can cause decreased production and economic losses. This disease is generally caused by the soil-borne pathogenic fungus Sclerotium rolfsii or Athelia rolfsii. The macroscopic and microscopic morphologies of the two species of the fungus Sclerotium rolfsii and Athelia rolfsii are the same and difficult to distinguish, so molecular identification is needed to determine the species. The research aims to isolate and molecularly identify fungi that cause stem rot disease in local legume plants in Bali. Research methods include isolation of pathogenic fungi from legumes showing symptoms of stem rot disease in Bali, pathogenicity test, identification of the highest levels of virulent isolates, DNA extraction, DNA amplification by PCR, and electrophoresis, ITS region sequencing, and computer analysis sequences DNA. The results of isolation pathogens that cause stem rot disease in Bali's local legume plants obtained six fungal isolates coded SKT, SKB1, SKB2 SKB3, SKL and SKN isolates. SKT isolates had the highest virulence rate after the pathogenicity test of peanut plants. Molecular identification results show that SKT isolate is Athelia rolfsii, because it's in a clade with Athelia rolfsii fungi sequences in GenBank with 100% Bootstrap support.

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“…They are then dried and cut into small pieces and placed in a petri dish with PDA medium, incubated for 2 days at room temperature, and the growth of pathogenic fungi is then observed under a microscope. Following its purification, the pathogen is spread and examined for the following step (Parwanayoni et al, 2021).…”