Genetic diversity of Lophodermium piceae in South Finland

Abstract

Lophodermium piceae, the dominant needle endophyte of Norway spruce (Picea abies), is known to be extremely diverse. This work aimed to test the possible occurrence of cryptic species within the morphological species L. piceae. Genetic variation in 36 South Finnish L. piceae isolates originating from six localities was investigated by comparing DNA sequences of three genetic markers. One of the markers was the internal transcribed sequence (ITS) of the ribosomal DNA and the other two (LP1 and LP2) were based on sequence characterized amplified regions designed for L. piceae. The LP2 marker could be detected only from isolates of L. piceae but not from 20 other ascomycete species tested. This sequence, therefore, is considered as a species-specific marker for L. piceae. For comparison, ITS sequences of isolates representing two other Lophodermium species, L. pinastri and L. seditiosum, were also investigated. In a neighbor-joining analysis of ITS sequences all L. piceae isolates fell into one cluster, which was clearly separate from those of L. pinastri and L. seditiosum. Dendrograms of the three markers were incongruent indicating that the L. piceae population examined consisted of a single phylogenetic species. No geographical differentiation was observed. Our results confirm that L. piceae is a genetically highly diverse endophytic species. © 2007 The Authors.