Analysis of variability among the isolates of Peronosclerospora sorghi from sorghum and cornbased on restriction fragment length polymorphismof ITS region of ribosomal DNA

Abstract

Downy mildew, caused by Peronosclerospora sorghi [Weston and Uppal (Shaw)], is one of the most serious diseases of sorghum and corn worldwide. Pathogenic variability among various isolates of P. sorghi has been reported. However, the molecular relationships between the isolates from sorghum and corn are unknown. In the present study DNA was extracted from P. sorghi isolates from sorghum and corn collected from different locations of Tamil Nadu, India, and their genetic variability was investigated using restriction fragment length polymorphism (RFLP) analysis of the PCR-amplified internal transcribed spacer (ITS) region of ribosomal DNA. PCR amplification of the ITS regions of the P. sorghi isolates from sorghum and corn gave products of approximately 550 base pairs in length with slight variations in a few isolates. Restriction fragment length polymorphism analysis of the ITS regions of nuclear rDNA of P. sorghi with HhaI, EcoRI and MspI confirmed the heterogeneity among the P. sorghi isolates from sorghum and corn.