Rice blast is not only one of the earliest known plant disease but also one of the most widely distributed, occurring in every region of the world where rice is grown. Ten isolates of Pyricularia oryzae causing rice blast disease... more
Rice blast is not only one of the earliest known plant
disease but also one of the most widely distributed, occurring in
every region of the world where rice is grown. Ten isolates of
Pyricularia oryzae causing rice blast disease were evaluated for
their morphological, pathogenic, virulence and genetic
characterization using RAPD marker. Isolates were classified
into three groups based on pathogenicity viz. severely
pathogenic, moderately pathogenic and mildly pathogenic and
also into four another gropus i.e. PG-I, PG-II, PG-III and PG-IV
based on cultural & morphological characteristics. The molecular
polymorphism among isolates by means were analyzed by means
of RAPD-PCR and the genetic coefficient matrix derived from
the scores of the RAPD profile showed that minimum and
maximum per cent similarities among isolates were in the range
of 80 to 35 percent respectively. The cluster analysis by
unweighted pair group method with arithmetic average
(UPGMA) separated the isolates into two major groups at 0.53 of
similarity coefficient. Through morphological characterization,
pathogenicity and RAPD grouping of isolates suggested no
correlation among test isolates but genetic variability among
P.oryzae isolates should be taken into account for the screening
of blast resistant rice genotypes.
