Browsing by Author "Mekuria Tsegaye"

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    Morphological and Molecular Characterizations of wilt disease of Ginger (Zingiber officinale Roscoe) Caused by Fusarium sp
    (Addis Ababa University, 2015) Mekuria Tsegaye; Alemu Tesfaye (PhD)
    Ginger rhizome, pseudostem, leaf and soil samples were collected from ginger growing areas of southwestern Ethiopia. Fungal pathogens were isolated from ginger parts showing vascular browning symptoms and soil following standard methods. Isolation revealed fungal isolates belonging to four genera: Fusarium, Penicillium, Aspergillus andTrichoderma. Out of 24 fungal isolates 14 isolates were Fusarium species. In vitropathogenicity test resulted in pathogenicity index (PI) values ranging from 10.96% +1.55(AAUFG13) to 45.35% +11.57 (AAUFG6). Cultures of Fusarium species on PDAmedium showed white, creamy white, dull pink and pink coloration. They imparted dullwhite, orange, light reddish purple, intense reddish purple and dark reddish purple pigmentations on the riverse side. Canoe shaped macroconidia, ovoid microconidia and short phialides were pertinent to all of the Fusarium isolates. Based on their cultural and morphological characters the isolates were identified as Fusarium oxysporum. The ability of the isolates to induce rhizome rot confirmed the forma specials rank of the isolates as F. oxysporum f. sp. zingiberi (Foz). PCR- RFLP profile of the ITS1 rDNA region indicated genetic variation between the Fusarium isolates. In silco RFLP digestion of ITS1 rDNA sequences of F. oxysporum retrieved from the fungal ITSoneDB was performed using online restriction mapper software and restriction enzymes used in the actual experiment. The result of the in silco restriction digestion simulation was similar with the actual PCR_RFLP study supporting that the isolates are Fusarium oxysporum. Key words: Fusarium wilt; ITS1;Pathogenicity; PCR-RFLP; Rizhome rot