Rice sheath rot disease caused by Sarocladium oryzae is a seed
borne disease and is a major production constraint in some rice
growing countries. This study aimed to evaluate some of our local rice
entries to sheath rot infection with different isolates, elucidate their
phytotoxicity effect and the molecular variability among some
selected isolates derived from different locations. Data revealed that
Sakha 101 was the most resistant cultivar against sheath rot. The
Toxin of S. oryzae completely inhibited differentiation of rice roots
and negatively affected seed germination of rice and weeds. S. oryzae
isolates showed morphological variability and polymorphism in DNA,
high levels of genetic variability among isolates were identified.
Using MR specific primers revealed that the two bands (1500 and
1400bp) were found only in low virulent isolates. Using SRAP
dendogram supported the similarity of data. Moreover, using SCAR
and SRAP primers could be able to differentiate among S. oryzae
isolates collected from different locations or varieties and differed in
their virulence and classified in two main clusters as high and low
virulent. Thus, the molecular variability of S. oryzae isolates may be
an important consideration in breeding programs to develop resistance
for sheath rot disease.