Assessing genetic diversity in Peronosclerospora sorghi causing downy mildew on maize and sorghum

摘要

Downy mildew, caused by Peronosclerospora sorghi (Weston & Uppal) Shaw, is an economically important disease on maize (Zea mays L.) and sorghum [Sorghum bicolor (L.) Moench] in India. The isolates of P. sorghi infecting sorghum and maize are difficultto distinguish from each other using morphologic criteria. However, there is wide variability in pathogenic and molecular characters among isolates of P. sorghi from maize, sorghum and wild sorghum. Therefore, studies were undertaken to assess the genetic variability in isolates of P. sorghi causing downy mildew on maize and sorghum by RAPD method during 2013 at Tamil Nadu Agricultural University, Coimbatore. A total of 65 reproducible RAPD bands were obtained with 15 selected primers on 11 isolates ofP. sorghi tested. Each primer yielded on an average of 6 RAPD fragments and molecular size of amplicons ranged from 250 bp to 2.0 kb. The 11 isolates were grouped into two main clusters (A and B) on the basis of cluster analysis of the pooled data for all 15 primers using unweighted pair group method with arithmetic mean (UPGMA). All the maize and sorghum isolates were grouped together in cluster A and cluster B respectively, confirming the genetic diversity among the isolates infecting both maize andsorghum.