Assessment of molecular variability among rice leaf and neck blast isolates of Pyricularia oryzae using MGM and RAPD markers

Abstract

Rice blast caused by Pyricularia oryzae is one of the most destructive diseases in the world. A total of 50 isolates of P. oryzae were collected from major rice growing areas in southern part of India. Out of fifty isolates, 33 were leaf blast and 17 were neck blast isolates. The present investigation was undertaken with an aim to know the variability among leaf blast and neck blast pathogen populations. Magnaporthe grisea microsatellite (MGM) markers and random amplified polymorphic DNA (RAPD) markers were used to study molecular variability among these isolates. The polymorphic information content was high for RAPD primers i.e., 0.78 whereas, MGM primers showed 0.52 only. Hence, the study of genetic diversity among P. oryzae isolates using RAPD primers was more useful than MGM primers. The similarity coefficient among the isolates ranged from 0.47 to 0.95. The RAPD analysis formed four main clusters (I–IV) at Jaccard similarity coefficient of 0.67. This grouping revealed that the isolates from south India have high level of genetic variation at geographic locations but not at leaf and neck specificity.