HASSANKIADEH A.A., KAZEMPOUR M.N., DEHKAEI F.P., RAHIMIAN H.
Abstract
Xanthomonas oryzae pv. oryzae, the causal agent of bacterial leaf blight (BLB) in the rice has been occurring as an increasing
and important problem in Iran in recent years. Despite the fact that it is one of the main pathogens of rice in northern
Iran, the biology of this bacterium in the Caspian Sea agro-ecosystem region is poorly understood. In this study, samples of
infected plants were collected from different areas of Guilan province during the spring and summer of 2005–2006. In order
to isolate bacteria, infected tissues of leaves, stems and roots were crushed in peptone water and 100 ìl of this juice was
cultured on NA and YDC media containing cycloheximide (50 ìg/ml). After 48 to 72 hours bacterial colonies were selected
and purifi ed. Their morphological, physiological and biochemical characteristics were tested. A polymerase chain reaction
(PCR) technique was developed to detect the presence of X. o. pv. oryzae in rice seeds as well as to study the transmission of
this bacterium from seed to plant. Primers TXT and TXT4R from an insertion sequence (IS1113) of the pathogen were used
to amplify a 964-bp DNA fragment. X. o. pv. oryzae was detected from the seed washes and DNA extracted from the seed
washes of naturally infected seeds of cv. Hashemie. When the naturally infected seeds were stored at ambient temperature,
the pathogen was recovered from them up to 10 months later. The BLB bacterium was also detected in seedlings, mature
plants and harvested seeds of plants raised from naturally infected seeds. To the best of our knowledge, this is the fi rst record
of seed-borne feasibility of bacterial leaf blight agent in Iran.
Key words:
Xanthomonas oryzae pv. oryzae, rice, seed-borne, PCR