Submitted to: Canadian Journal of Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/18/2000
Publication Date: N/A
Citation: N/A Interpretive Summary: Fungi in the genus Neonectria as the asexual Cylindrocarpon state cause a number of canker and root diseases of fruit trees and conifers especially as seedlings. The taxonomy of this group of fungi is confused and identification of species is difficult. Accurate identification is essential for managing the diseases caused by these fungi. This research uses molecular sequences of part of the DNA in the energy-producing body of the cell to determine the relationships among species in this group of fungi. It was determined that all these species are relatively closely related and should be placed in the same genus. Within the genus three major groups were identified. These groups could be differentiated of characteristics of the fungi that are visible with the light microscope. Using molecular data this research confirms earlier work that was hypothesized based on non-molecular data. These results will form the basis for differentiating these fungal species resulting in their more accurate identification and better management of the diseases that these fungi cause.
Technical Abstract: Mitochondrial small subunit (mitSSU) rDNA sequences were used to study phylogenetic relationships in Neonectria (anamorph = Cylindrocarpon; Ascomycetes, Hypocreales). Twelve isolates representing seven species in five taxonomically informal groups of Neonectria were subjected to phylogenetic analysis with Fusarium inflexum and Nectria cinnabarina as outgroups. All of the Neonectria species formed a strongly supported clade with respect to the outgroups, indicating a single ascomycete genus for the holomorphs of Cylindrocarpon. Within the Neonectria clade there were well-supported, subclades that only partially corresponded to phenotype-defined groups. DNA sequence divergence among the twelve Neonectria isolates, 2.3--7.4%, was sufficient to resolve them. The results suggest that mitSSU rDNA region is appropriate for pyhlogenetic analysis of Neonectria and Cylindrocarpon. The folliwng new combinations are proposed: Neonectria coronata, Neonectria discophora, Neonectria neomacrospora, Neonectria radiciola, Neonectria rugulosa, Neonectria veuillotiana.