Identifikasi Morfologi, Genetik, dan Patogenisitas Cendawan Fusarium spp. Penyebab Penyakit Busuk Pangkal Bawang Merah dari Dataran Rendah dan Tinggi Sumatera Utara

Abstract

Shallot basal plate rot disease (moler) caused by Fusarium spp. is one of the main shallot diseases that caused low productivity of shallots in North Sumatra. Fusarium has a fairly high diversity of species in shallot plants, some of which are pathogenic and non-pathogenic. Morphological identification of Fusarium species is often inaccurate, so differences between closely related species and their pathogenicity are difficult to observe. This study was aimed to identify the morphology, genetics, and pathogenicity as well as to analyze the kinship relationship of Fusarium spp. originating from the highlands and lowlands of North Sumatra. There are 9 fungy successfully isolated from infected shallot plants from 6 cities/districts in North Sumatra, i.e. Medan, Batubara, Serdang Bedagai, Simalungun, Samosir, and Dairi. Morphological identification showed that 9 isolates had various colony color, average colony growth rate, conidia density, shape and size of microconidia, macroconidia, and chlamydospores. The results of genetic identification by PCR and sequencing, 9 isolates belonged to 3 Fusarium species, namely Fusarium oxysporum, Fusarium phaseoli, Fusarium solani, and 1 uncultured fungus. Pathogenicity test results showed that all isolates were classified as virulent pathogens to local shallots of Samosir variety. Meanwhile, from the analysis of the phylogeny tree and genetic distance, F. oxysporum from Medan and Simalungun along with 4 reference isolates had a very close relationship so they were grouped in Clade 1, F. solani from Batubara and 2 reference isolates were grouped into Clade 2, and F. solani from Medan and Simalungun, unculture fungus from Samosir, F. phaseoli from Serdang Bedagai, F. solani from Samosir and Dairi along with their 12 reference isolates were grouped into Clade 3.