Landcare Research - Manaaki Whenua

Landcare-Research -Manaaki Whenua

Molecular studies

Species relationships

<em>Torrendiella</em>: neighbour-joining tree based on ITS, chitin synthesase, and partial lsu rDNA genes.The DNA sequence data supports the morphological data in suggesting there are a range of host-specialised, leaf-inhabiting species in Autralasia, distinct from the Acacia-specialised T. eucalypti. Additional species no doubt await discovery.

Most of these species remain to be formally described.

Host relationships

There are several plant genera that host more than one species of Torrendiella. Have the fungi diverged on the host following a single ancestral adaptation to that host or have the fungi made several independent adaptations to the host?

<em>Torrendiella</em>: neighbour-joing tree based on ITS and chitin synthesase genes (species on <em>Nothofagus</em>). Preliminary data based on ITS, partial lsu rDNA and chitin synthesase genes suggest the Nothofagus-inhabiting Torrendiella species may form a monophyletic group. If this is the case, then it is possible these species have diverged following an initial adaptation to Nothofagus by their common ancestor.

We intend to extend this work by examining more genes to try to better resolve the tree. A number of the branches at the base of the "nothofagus clade" are poorly supported. We also intend to examine a wider range of Metrosideros-inhabiting species, to see if these taxa show the same pattern of relationship as the Nothofagus-inhabiting species. Metrosideros is a genus that hosts several distinct Torrendiella species.

Relationships at the family level

<em>Torrendiella</em>: neighbour-joining tree based on ITS and partial lsu rDNA sequences.The general morphology and apothecial anatomy of Torrendiella suggest a close relationship with Rutstroemia, the type genus of Rutstroemiaceae, a family recently segregated from the broader Sclerotiniaceae.

However, if Torrendiella is included in the tree published by Holst-Jensen et al. (Holst-Jensen, A.; Kohn, L.M.; Schumacher, T. 1997: Nuclear rDNA phylogeny of the Sclerotiniaceae, Mycologia 89: 885 – 899), it does not cluster with either the Rutstroemiaceae or Sclerotiniaceae, but rather forms a separate group within the Helotiales.