A dendrogram was generated by SM coefficient.
The similarity degree (SD) value for the isolates from 0.76 to 0.92. Analysis with Dice and Jaccard’s coefficients
showed analogous results. Six loci specific for Gujarat
11 were identified. Three pairs of isolate Malan–Mandya-
NBI (0.92), Pantnagar–Jagadalpur (0.92) and Karjat
CV184–Warangal (0.90) were closely related with high
SD values. For a SD higher than 0.75, it was possible to
differentiate the twenty isolates into two major clusters,
A and B, each consisting of two subclusters. It was observed
that all the three isolates from Uttaranchal were grouped
together in subcluster A1. Similarly, isolates from Assam
and Orrisa were found to be grouped together in subcluster
B2, while isolates from Karnataka, Maharashtra and Andhra
Pradesh were distributed almost equally in clusters A and B.
The analysis of RAPD polymorphism in isolates of M.
grisea from different regions across India revealed the
occurrence of high level of polymorphism, indicating a ranged wide and diverse genetic base. A repeat sequence termed
MGR586 was identified in the genome of rice infecting
strains of M. grisea7. This sequence has been widely used
for DNA fingerprinting of M. grisea to investigate the
epidemiology of the rice blast disease8–11. Another retrotransposon,
fosbury has also been used for genetic differentiation
studies7 and the results indicate that isolates
from Bangladesh lack both MGR586 and fosbury.
MGR586 probe also failed to detect karyotypic changes19.
Thus there is a need to develop different DNA fingerprinting
techniques to identify various forms of M. grisea
diversity. RAPD markers used in this investigation increase
the marker density for finding out genetic relationships.