Analysis of Population Structure of Magnaporthe grisea Using Genome Specific Microsatellite Markers

In order to understand the pathogen's genetic diversity and dynamics of fungal populations, 34 rice blast isolates collected from various blast endemic areas of India were analyzed using Magnaporthe grisea genome specific microsatellite markers (MGM) and repeat element based Pot2 primer. All the blast isolates showed average pair wise similarities in the range of 0.15 to 0.9 and suggested the large variations with in the isolates collected from the different places. To know the genetic relationship among the blast isolates, a dendogram was generated based on analysis of MGM and Pot2 primers separately and in combination using SHAN/UPGMA program. The cluster analysis grouped all the blast isolates in to different clusters mostly based on the location, from where they were collected. Based on International blast differential lines containing single resistance genes, it was identified that AVR Pi-k gene was present predominantly in isolate collected from Nellore in costal Andhra Pradesh; and AVR Pi-2 and AVR Pi-4 genes in isolates collected from Mandya (Karnataka). The isolates collected from Almora, Ranchi and Nawagam showed the presence of AVR Pi-1 and AVR Pi-4a genes. The present study helped us to understand the population diversity and their AVR genes spectra in the blast hotspot regions of India, which can be useful in deployment strategies for blast resistance genes in rice improvement programmes.