Phylogenetic diversity of true morels (Morchella), the main edible non-timber product from native Patagonian forests of Argentina

Morchella species are edible fungi in high demand and therefore command high prices in world markets. Phenotypic-based identification at the species-level remains inadequate because of their complex life cycles, minor differences and plasticity of morphological characteristics between species, and the lack of agreement between scientific and common names. In Patagonia-Argentina, morels are associated with native forests of Austrocedrus chilensis (Cordilleran or Chilean cypress) and Nothofagus antarctica (ñire) and several exotic conifers that were introduced from western North America. Little is known about their taxonomy and phylogenetic relationships with other species in the genus. This work focused on the identification of collections of Morchella from Patagonia and their phylogenetic relationships with other species from the Northern Hemisphere. The comparison was made by analysis of DNA sequences obtained from four loci: the nuclear ribosomal internal transcribed spacer region (ITS) and the partial RNA polymerase I gene (RPB1) for the complete collection; and ITS, RPB1, RNA polymerase II gene (RPB2), and translation elongation factor (EF1-α) for the species-rich Elata Subclade. Analyses of individual and combined data sets revealed that Patagonian morels belong to the Elata Clade and comprised three strongly supported species-level lineages from both Patagonian native forest, and exotic trees introduced from western North America. One lineage was identified as Morchella frustrata phylogenetic species Mel-2, which is known from the USA and Canada. The second lineage, which appeared to be 'fire-adapted', was identified as Morchella septimelata phylogenetic species (Mel-7), which is also known from the USA. This species was collected from burned native forests mainly composed of A. chilensis and N. antarctica but also Pseudotsuga menziesii (Mirb.) Blanco, which is native to western North America. The phylogenetic analyses suggested that the third species from Patagonia was nested within the species-rich Elata Subclade and represents a new species-level lineage (informally designated Mel-37) within Elata Clade. The present collections from Patagonia constitute the southernmost latitude from which Morchella has been reported to date. The identification of two Argentine morels as North American taxa is therefore a remarkable biogeographic pattern. In view of the hypothesis that the Elata Clade originated in western North America, we speculate that at least two of the lineages colonized South America from North America via long distance dispersal, migration or, more likely, they were introduced with the exotic tree species that they were collected near.

Comprehensive phylogenetic analysis of the genus Golovinomyces (Ascomycota: Erysiphales) reveals close evolutionary relationships with its host plants

The Erysiphaceae were originally parasitic to trees, and host shift from trees to herbs might have occurred many times independently in the tribes and genera. To investigate the evolutionary relationships between Golovinomyces species and their host plants, we conducted a comprehensive molecular phylogenetic analysis of this genus with 183 nucleotide sequences of ITS and 28S rDNA regions from samples collected worldwide. These sequences were divided into 11 distinct lineages. Ten of these lineages consist in each case of sequences from a single plant family or tribe, which suggests close evolutionary relationships of Golovinomyces species and their host plants. The basal five clades were composed of sequences each from a single tribe of the Asteraceae. This result supports speculation that co-speciation occurred between asteraceous hosts and Golovinomyces in the early evolution stage of this genus. Lineage XI at the most derived position of the tree includes sequences from a wide range of host families and is divided into many species with close genetic affinity. Sequences from the putative G. orontii group were separated into three groups, suggesting that G. orontii is a species complex.