RAPD analysis and rDNA gene sequence based phylogeny of Bipolaris sorokiniana, a spot blotch pathogen of sorghum

Abstract

Sorghum [Sorghum bicolor (L) Moench] is the one of the most important cereal crops in the world. It is the staple food grain for over 750 million people who live in the semi-arid tropics of Africa, Asia, and Latin America. Global pro-duction of sorghum is currently estimated to be 57.6 million tonnes, with Asian countries contributing 20% of the total production. Within Asia, India is the largest producer of sorghum grain. Recently there have been severe signs of sorghum decline caused by Bipolaris sorokiniana resulting in decreased production of sorghum in villages of Kalimpong and Darjeeling. In the present study, initially, several strains of the fungus were isolated from diseased leaves of Sorghum bicolor and Triticum aestivum which were morphologically identified as Bipolaris sorokiniana. Genomic DNA of B. sorokiniana isolated from infected leaves was purified and PCR amplification of 18s rDNA was done using specific primers. Amplified product (1190 bp) was sequenced and aligned against ex-type strain sequences of B. sorokiniana from NCBI GenBank using BLAST and phylogenetic analysis was done using MEGA4 software. RAPD PCR analysis and DGGE analysis of amplified genomic DNA were done. The evolutionary history was inferred using the UPGMA method. Amplification of ITS region of the rDNA can be considered as a rapid technique for identifying pathogens successfully in all cases.