Genetic diversity among Fusarium species associated with sorghum stalk rot in Southern Ethiopia

Fusaria are very diverse and destructive pathogens affecting different crops. However, their identity and diversity are unresolved in countries like Ethiopia, where various crop species are grown under differing environmental conditions. The objectives of this paper were to identify Fusarium spp. associated with sorghum stalk rot in Southern Ethiopia, and elucidate the genetic diversity within and between the species. For this purpose, Fusaria associated with sorghum from two locations in Southern Ethiopia were isolated. Sequencing of the elongation factor 1-alpha gene (EF-1α) was used for species identification. In addition, AFLP analysis was employed for further diversity studies within and between the Fusarium spp. Sequence analyses revealed the presence of two Fusarium spp. The first was identified as Fusarium andiyazi, while the identity of the second remains to be solved. AFLP analysis clustered the isolates into two major groups. The Dice similarity coefficients ranged from 0.39 to 0.91 for isolates of F. andiyazi while isolates within the new Fusarium spp. had a Dice similarity coefficient varying between 0.69 and 0.96. Cluster analysis and principal coordinate analysis clearly indicated a genetic separation between the two species. Both groups were pathogenic to mature sorghum plants following a toothpick inoculation test. More researches are required to identify the new species and elucidate the pathogenicity of the isolates.   Key words: EF-1α, Fusarium andiyazi, genetic similarity, sequence analysis, Sorghum bicolor.