Small proteins of plant-pathogenic fungi secreted during host colonization

Small proteins secreted by plant pathogenic fungi in their hosts have been implicated in disease symptom development as well as in R-gene mediated disease resistance. Characteristically, this class of proteins shows very limited phylogenetic distribution, possibly due to accelerated evolution stimulated by plant-pathogen arms races. Partly due to lack of clues from primary sequences, insight into the biochemical functions or molecular targets of these proteins has been slow to emerge. However, for some proteins important progress has recently been made in this direction. Expression of the genes for small secreted proteins is in many cases specifically induced after infection, which should help to advance our still very limited understanding of how plant pathogens recognize and respond to the host environment.