FIRST REPORTS OF BACTERIAL LEAF SPOT OF LETTUCE (LACTUCA SATIVA) CAUSED XANTHOMONAS CAMPESTRIS PV. VITIANS IN SAUDI ARABIA

In April 2008, lettuce (Lactuca sativa L. cv. Darkland) plants grown in numerous lesions typical of bacterial leaf spot. Leaf lesions were irregular, small, pale green to black and 2 to 5. Bacteria were isolated from diseased leaf tissues by cutting leaves into small pieces. All were slightly pectolytic but not amyltolytic. All were identified as vitians. The bacterium was identified with specific oligonucleotide primers (2). Approximately 700-bp DNA fragment from total genomic DNA of all X. campestris pv. Vitians performed by using bacterial cultures grown on YDC for 48 h at 28˚ bacterial concentration was adjusted to 106 CFU/ml. leaves of 45-week-suspension. The inoculated and sterile-water-sprayed control plants were covered with polyethylene bags for 48 the bags were removed and plants were transferred to greenhouse at 25 to 28˚C (1). Darkland, causing typical bacterial leaf spot symptoms by 2 weeks after inoculation. The bacterium was reisolated from inoculated plants and identified as X. campestris pv. vitians biochemical tests as described above. To our knowledge, this is the first report of bacterial leaf spot of lettuce by vitians in Saudi Arabia