Year: 2018 | Month: April | Volume 11 | Issue 2
Status of Magnaporthe oryzae Infection in Different Districts of Karnataka, India and Establishment of Monoconidial Cultures for Understanding Genetic Diversity
Abstract:
Blast disease caused by Magnaporthe oryzae B.C. Couch is one of the major production constraints and main pathological threats to rice crop around the world. A total of 171 places were visited and samples were collected from 101 diseased plots from different geographical regions of Karnataka, India during 2012-2014. Different parameters like locations, variety name, age of the crop, type of infection and severity of the disease were recorded. Among the total infection types, leaf blast was found to dominate followed by neck, collar, node and panicle blast. Disease incidence of 64.44%, 68.75%, 60.71% and 55.55% was recorded from major rice growing districts of South Karnataka viz., Chamarajanagar, Kodagu, Mandya and Mysuru districts respectively. Varieties MTU-1001, Jyothi and Sona Masuri remained highly susceptible in these four districts. This was followed by Minilong, IR64, Jaya, KCP-1, Rajamudi, Rajbhoga and KRH-4 varieties from different districts of Karnataka. Newly developed blast resistant varieties namely Rasi, KRH 4, Raksha and Mugad Siri 1253 were also found to be susceptible in some of the regions of Karnataka indicating breakdown of resistance. Thus, the emerging pathogenic variants among fungal populations trigger serious and incessant threat to the newly released resistant varieties. Seventy two monoconidial M. oryzae isolates were obtained and pure cultures were established for understanding molecular diversity of the pathogen.
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