RAPD and Pathotype Analyses of Magnaporthe grisea Populations from the north-western Himalayan Region of India

Using random amplified polymorphic DNA (RAPD) analysis, 250 isolates of Magnaporthe grisea collected from the north-western Himalayan region were separated into 25 DNA fingerprint groups or lineages. Of these 25 groups, 13 were exclusive to isolates obtained from Himachal Pradesh (HP), five from Uttaranchal and one from Jammu and Kashmir (J & K), India. Seven remaining groups were composed of isolates from different locations and 26 isolates could not be classified. Although RAPD analysis revealed high genetic variability among M. grisea populations from HP and J & K, genetic variation was low in the isolates collected from Uttaranchal. DNA fingerprint groups specific to a particular geographical region were also obtained. Pathogen population consisting of 119 isolates from north-western Himalayan region has been grouped into 52 pathotypes on the basis of disease reaction on international differential rice lines. Highest frequency of virulence was trapped on the rice line Caloro (Pi)ks) followed by NP125 (Pi)? and K-60 (Pi)kp) while it was lowest on Tadukan (Pi)ta and/or Pi)ta2) and BL-1(Pi)b and Pi)sh). Virulence was rare on Fukunishiki (Pi)zs). Rice line Tetep (Pi)kh+?) was found to be highly effective in north-western Himalayan region as none of the isolate could infect this line. These blast resistant rice lines can be used in resistance breeding for the effective management of rice blast in this region of India. Introduction Management of rice blast caused