A MOLECULAR TOOL FOR DIFFERENCIATION OF XANTHOMONAS ORYZAE PATHOVARS ISOLATED FROM RICE

In rice crop, bacterial blight disease is caused by the bacteria Xanthomonas oryzae pv. oryzae and bacterial streak disease is caused by Xanthomonas oryzae pv. oryzicola. Most of the time symptoms produced by these pathogens are confusing and cannot be easily differentiated. The colony characteristics and biochemical tests are also quite similar. In present study a molecular tool based on Insertion sequence primer has been used to differentiate the pathovars. For this purpose infected leaf samples of rice with symptoms of bacterial blight disease were collected from rice growing areas of Punjab province during the year 2011 and studied in the Department of Biosciences, COMSATS Institute of Information Technology, Sahiwal, Pakistan. Twenty five bacterial isolates were isolated from leaf samples. Afterwards, insertion sequence based polymerase chain reaction (PCR) was applied using J1 primer for confirmation of isolates to be Xanthomonas oryzae pv. oryzae or Xanthomonas oryzae pv. oryzicola. Out of 25 isolates, 18 were confirmed to be Xanthomonas oryzae pv. oryzae by amplifying a strong band of 500bp. while 7 isolates were found to be Xanthomonas oryzae pv. oryzicola by amplifying bands of ~430bp and ~340bp.