Genetic relatedness of rice blast fungus (Pyricularia oryzae) isolates from two agro ecologies of Burundi

Abstract

Rice blast disease caused by fungus Pyricularia oryzae is one of the most destructive diseases in rice-producing areas of Burundi. To understand species diversity of P. oryzae isolated, molecular markers targeting the Internal Transcribed Spacer (ITS) and Translation Elongation Factor (TEF) regions followed with Sanger sequencing were used. Thirty-five isolates of P. oryzae were amplified in Polymerase Chain Reaction (PCR) using primers TS1F and 2R, ITS3F and 4R, ITS1F and 4R, ITS4F and 5R and EF1-983F and EF1-2218R. The positive PCR amplicons for ITS1F and ITS4R and TEF1-983 and EF1-2218F were Sanger sequenced. The PCR results showed a difference in banding patterns between isolates ranging from 220-1235bp. The isolates amplified by TS1F and 2R, ITS3F and 4R, ITS1F and 4R, ITS4F and 5R and EF1-983F and EF1-2218R showed bands size of 220bp, 350bp, 390bp, 550bp and 1235bp respectively. The Sanger sequence products released that all the isolates were Pyricularia oryzae from rice host with limited variations in the analyzed genes. Phylogenetic analysis showed narrow genetic diversity between P. oryzae collected in high and middle altitudes regions of Burundi. The single nucleotides polymorphisms observed among the isolates in both ITS and EF regions may indicate the level of virulence or pathogenicity among the Burundi Isolates may differs, hence calling for further studies. Therefore, these findings call for plants breeders to initiate/proceed with breeding strategies targeting to overcome the rapid evolving Pyricularia oryzae strains by breeding resistant rice cultivars to rice blast disease in the country.