Outdoor ponds are the most practical means to cultivate algae for biofuel production. S dimorphus, a green microalga with potential use as a biofuel crop, grown in ponds is susceptible to infection and disease caused by primitive chytrid-like fungi. Infection can kill virtually all of the algal cells in a pond within days. As a first step toward the development of resistant strains, we advanced our molecular understanding of algae and chytrid- like fungi interactions by observing infection-induced changes in the levels of proteins of S. dimorphus. Peptide mass spectrometry revealed ̃2,500 proteins change in abundance in S. dimorphus after FD61 (chytrid-like fungi) infection. We observed several proteins to be homologous to proteins involved in plant defense including proteins known to be precursors of plant defense hormones Salicylic Acid (SA) and Jasmonic Acid (JA). SA mediates defense against biotrophic pathogens while JA mediates defense against necrotrophic pathogens. BTH (SA analog) treatment of S. dimorphus delays FD01 infection and meJA treatment of S. dimorphus accelerates FD61 infection. BTH and meJA treatment at high concentration suppresses S. dimorphus growth (non-infected). We hypothesize that if SA and JA pathways exist in algae, a mutant less sensitive to JA will be less susceptible to chytrid infection and a mutant less sensitive to SA will be more susceptible to chytrid infection. To further test this hypothesis we will perform a library screen to find such a mutant and test candidates for susceptibility to chytrid infectio
