Differentiating characteristics between Melampsoridium rusts infecting birch and alder leaves

Abstract

Melampsoridium rust epidemics on alder occurred in Estonia in 1996–1998, and in Finland in 1997–1998. In this study we show that the length and roundness of urediniospores and the PCR-amplified internal transcribed spacer (ITS) sequences of rusts occurring on Alnus and Betula are different. Morphologically the rust on alder belongs to M. hiratsukanum, and based on our results is not conspecific with M. betulinum. The sequence comparisons indicated that 5.8S rDNA was similar in both Melampsoridium species and identical to several Cronartium sequences. The 5.8S rDNA of Melampsoridium was also more similar to Pucciniastrum, Chrysomyxa and Puccinia than to Melampsora species. The ITS sequences were distinct from all other rusts, but relatively similar to Cronartium, Pucciniastrum and Chrysomyxa sequences.

Key Words:

• 5.8S rDNA
• Alnus
• Betula
• DGGE
• ITS
• Uredinales
• urediniospore