Unseen fungal biodiversity and complex inter-organismal interactions in Protea flower heads.

A unique microbiome occurs within the flower heads of various Protea species endemic to Africa. These include two lineages of ophiostomatoid fungi, Knoxdaviesia (Microascales) and Sporothrix (Ophiostomatales), that have members occurring exclusively in this environment and that rely on mites as their primary mode of spore dissemination. The mites, in turn, attach to the bodies of Protea -pollinating beetles and the beaks and bodies of birds for long-distance movement, establishing a hierarchical dispersal network for the ophiostomatoid fungi. This inter-organismal network is highly successful, achieving fungal dispersal over vast distances. Multiple species of fungi, mites and bacteria have been described from this unique niche over the past four decades. The intricacies of their symbiotic interactions continue to be unravelled. This review covers all current knowledge of the "distinctly African" Protea -ophiostomatoid fungus environment and illustrates the depth of a fascinating unseen fungal biodiversity niche. [Display omitted] • Two lineages of ophiostomatoid fungi occur exclusively in Protea flower heads. • Mites act as primary spore vectors and are phoretic on other arthropods and birds. • Recombination and hierarchical dispersal facilitate massive genetic diversity. • Early colonisation and niche differentiation likely alleviate interspecific competition. • Insights from this fungal niche benefit biodiversity and plant health research. [ABSTRACT FROM AUTHOR]