Uncovering the Morphological and Genetical Heterogeneity of Pyricularia oryzae (cooke) sacc. in Southwestern Region of Bangladesh

Abstract

Significant yield losses are reported due to blast disease caused by Pyricularia oryzae across all rice growing areas of the world. Though, management strategies reduce disease significantly but blast epidemics are still common. This research was aimed to determine the variability among the 19 Pyricularia oryzae isolates of South-Western regions of Bangladesh. Morphological variability was determined based on nine morphological components like front mycelial color, reverse mycelial color, growth behavior, conidial length (μm), conidial  width (μm), conidial color, radial growth at 12 days (mm), 14 days (mm) and 16 days (mm) after incubation. Cluster analysis considering nine morphological components showed five distinct groups. Front and reverse mycelial color, growth behavior and conidial length played more than 80% role in generating variation among the nine tested components. Higher genetic variation was also detected among the 19 isolates of P. oryzae.  Here, larger numbers of amplified DNA fragments was formed by Primers UCB-155 which showed distinct polymorphism. Between two clusters, Cluster II consists of 18 isolates that were originated from different origin but having maximum 94% genetical similarity. Cluster I contain only one isolates PO-16. From pair wise distance matrix, maximum distance (80%) was found between PO-16 and PO-03 isolates and minimum distance (6%) was obtained between the isolates PO-11 and PO-12. Results of this experiment revealed that, higher genetic diversity among isolates of P. oryzae existed in the south western region of Bangladesh but there has no direct relation with genetic diversity and geographical origin.