Random amplified polymorphic DNA and polymerase chain reaction markers forthe differentiation and detection of Stenocarpella maydis in maize seeds

The genetic relationship of 34 isolates of Stenocarpella maydis from differ ent geographic regions in South Africa was analysed by random amplified pol ymorphic DNA (RAPD) and ribosomal DNA markers. Two genetic groups were diff erentiated by using three RAPD primers and correlated to the cultural morph ology of the isolates. Of all the isolates tested, 79.4% were clustered int o RAPD group I (RG I), which did not sporulate when cultured on potato dext rose agar (PDA) at 25 degreesC for 10 days. The rest of the isolates design ated as RG II sporulated on PDA medium and showed a higher genetic variatio n. Ribosomal DNA (rDNA) was amplified using polymerase chain reaction (PCR) with the universal primers, internal transcribed spacer (ITS) 1 and ITS 4. Restriction digestion of PCR products displayed three types (RF A, RF B an d RF C) of profiles. RF A was in accordance with RG I. RF B was consistent with RC II except for one isolate, U5. However, U5 displayed a unique profi le and had no restriction sites for Hpa II and Hae III. The results indicat e that two distinct genetic groups exist among S. maydis isolates from maiz e in S. Africa. The ITS1 and ITS2 regions of rDNA were sequenced and primer s were designed. The designed primer pair P1/P2 permitted a sensitive and s pecific detection of S. maydis.