Ascostromata of Botryosphaeria dothidea

Asci of Botryosphaeria dothidea

Ascospores of Botryosphaeria dothidea

Botryosphaeria dothidea (Moug. : Fr.) Cesati & De Notaris (anamorph Fusicoccum aesculi Corda) is the type species of the genus and Botryosphaeriaceae. The family includes a large number of species and genera with similar life histories. Most are known as latent plant pathogens that cause die-back, cankers, leaf spots or fruit rots on the plants they infect under conditions of stress. These fungi are widespread and common, almost ubiquitous, in endophytic communities in woody plants (Slippers & Wingfield 2007). The prominence of B. dothidea relates to its common occurrence in Europe (see recent assessment in Piskur et al. 2010) where members of Botryosphaeriaceae were commonly encountered and described by a number of mycologists in the 19th century. There has, however, been significant taxonomic confusion in Botryosphaeriaceae, which has led to numerous taxa and important plant pathogens being lumped under B. dothidea and a few close relatives. It was only after the application of DNA sequence-based phylogenetic tools and the epitypification of key species that the real taxonomic diversity in the group could be unraveled (Slippers et al. 2004). Although numerous species have since been described that have previously been confused with B. dothidea, it remains amongst the most widespread and important pathogens of trees around the world, including important fruit crops and forestry trees. Its hosts include trees such as Eucalyptus and Populus that are considered important for future fiber and potential energy production. The common occurrence and stress-associated diseases have led to the prediction that these fungi will play an important role as stress in plant communities increase due to climate change (Desprez-Loustau et al. 2006).

The order Botryosphaeriales has only recently been introduced in Dothideomycetes to accommodate Botryosphaeriaceae as sole family (Schoch et al. 2006). The class is amongst the largest in the Ascomycota and encompasses a collective of very diverse nutritional modes, including plant and insect pathogens, lichens, marine fungi and saprobes. The Botryosphaeriales groups as sister to Tubeufiaceae and Histeriales that are predominantly saprobes or weak plant parasites, but also include other modes of nutrition. The prominence of the plant infecting life style, and pathogenicity activated by the onset of stress amongst species of Botryosphaeriales, suggest that analysis of genomes in this order could reveal much about the evolution of plant parasitism in Dothideomycetes. In particular the B. dothidea genome could hold unique discoveries related to its extended endophytic or latent stage, as well as its ability to infect a very wide host range.

 
References:
Desprez-Loustau, M.L., Marcais, B., Nageleisen, L.M., Piou, D., Vannini, A., 2006. Interactive effects of drought and pathogens in forest trees. Annals of Forest Science 63, 597-612.

Piskur, B., Pavlic, D., Slippers, B., Ogris, N., Maresi, G., Wingfield, M.J., Jurc, D., 2011. Diversity and pathogenicity of Botryosphaeriaceae on declining Ostrya carpinifolia in Slovenia and Italy following extreme weather conditions. European Journal of Forest Research 130, 235-249.

Schoch, C., Shoemaker, R., Seifert, K., Hambleton, S., Spatafora, J.W., Crous, P.W., 2006. A multigene phylogeny of the Dothideomycetes using four nuclear loci. Mycologia 98, 1043-1054.

Slippers, B., Crous, P.W., Denman, S., Coutinho, T.A., Wingfield, B.D., Wingfield, M.J., 2004. Combined multiple gene genealogies and phenotypic characters differentiate several species previously identified as Botryosphaeria dothidea. Mycologia 96, 83-101.

Slippers, B., Wingfield, M.J., 2007. Botryosphaeriaceae as endophytes and latent pathogens of woody plants: diversity, ecology and impact. Fungal Biology Reviews 21, 90-106.