Population Biology Of Magnaporthe Grisea And Analysis Of Host Plant Resistance In Foxtail Millet Against Blast Disease

Abstract

Millets are known as Smart food crops and nutri-cereals . Foxtail millet is the most nutritive small grained millet. Copious constraints occur during cultivation of foxtail millet crop, among which blast disease incited by Magnaporthe grisea causes economic deprivation to the farmers. Outbreak of foxtail millet blast disease is a serious and recurrent problem in all foxtail millet growing regions of the world and its management is arduous. newlineThe present study consists of collection and isolation of Magnaporthe grisea isolates, characterization through cultural, morphological and molecular approaches, analysis of genetic diversity using SSR markers, identification of mating type and grass hopper repeat element, correlation and regression analysis of disease severity with weather parameters and identification of resistant genotypes against the blast disease. newlineA detailed survey was undertaken to assess the severity of blast disease of foxtail millet in the farmer s fields of ten districts viz., Tiruvannamalai, Vellore, Dharmapuri, Salem, Erode, Namakkal, Dindigul, Madurai, Virudhunagar and Thoothukudi of Tamil Nadu, India. The blast disease was recorded to an extent of 72.19 and 70.16 per cent, respectively in the foxtail millet varieties namely Co(Te) 7 and Co(Te) 5. newlineThirty two isolates of Magnaporthe were isolated from infected plant parts newlinecollected from different foxtail millet growing areas. Among the different culture media used, potato dextrose medium was found to be the best for the growth of M. grisea followed by tenai seed extract medium which recorded significantly the maximum mycelial growth of 9.0 cm on 15 DAI of the pathogen. Pathogenicity tests newlinewere performed with the field collected isolates of M. grisea on susceptible variety Co(Te) 7. The blast conidia sporulation was not observed on culture media. To get more sporulation of the blast pathogen, stem bits of the weed Paspalum distichum were used newlineas medium. Phenotypic characterization including mycelial growth, colony morphology and spore morphology we