ENDOPHYTES: FRIENDS OR FOES?
Lynne Boddy1 and I Chapela2
1University of Wales, Cardiff, UK; 2University of California, Berkeley, USA
The close phylogenetic proximity between endophytes and some well-known pathogenic fungi has been interpreted to suggest that endophytes are 'degenerate' forms of pathogens. However, this polarity is contradicted by closer phylogenetic analyses, as well as many ecological studies. On one hand, endophytes are much more widespread and abundant than recognized pathogenic species, pathogenicity traits are widely dispersed on the wider phylogeny of specific groups, survival and reproduction of endophytes is not dependent on their pathogenic behaviour, and traits identified as conveying pathogenicity might often be advantageous to both plant and fungal partners in the endophytic symbiosis. On the other hand, focusing on the pathogenic section of life histories of otherwise endophytic fungi has distracted attention from more fundamental questions that would help us understand the endophytic way of life and, in turn, its relevance in producing pathogenic relationships of economic importance. We present phylogenetic, ecological and physiological data from various biological groups to illustrate research avenues that could provide a wider understanding of this understudied universe of endophytic life. Examples will include Phomopsis, Rhabdocline, Lophodermium, Cryphonectria, Eutypa, Hypoxylon and xylariaceous ascomycete species, plus some wood-rotting Corticiaceae in woody and herbaceous tissues of angiosperm and coniferous trees. Reference will also be made to grass endophytes.