RAPD CHARACTERIZATION OF FUSARIUM-OXYSPORUM ASSOCIATED WITH WILT OF ANGSANA (PTEROCARPUS-INDICUS) IN SINGAPORE

Angsana (Pterocarpus indicus) is an important shade tree in Singapore. Since 1914 angsana has been under threat from a wilt disease caused b y Fusarium oxysporum. We have used the PCR based technique of Random A mplification of Polymorphic DNA (RAPD) to assess the genetic variabili ty of 39 isolates of F. oxysporum isolated from angsana. The isolates formed a homogeneous group with few polymorphic bands. The most signif icant polymorphic band distinguished four isolates obtained from one r egion (the Istana) of Singapore from the other 35 isolates. This diffe rence was supported by Southern analysis data using RAPD fragment OPA- 18(350) as a hybridization probe. Angsana isolates of F. oxysporum wer e easily distinguishable from 17 other F. oxysporum isolates from othe r hosts, and from ten isolates of F. solani from angsana.