M3.1: Mycosporines in spore-type specific development and corn anthracnose spreading

Daniela Nordzieke & James Kronstad

Colletotrichum graminicola is a hemibiotrophic plant pathogen causing anthracnose on Zea mays. This phytopathogenic fungus forms two morphological distinct asexual spores, oval and falcate conidia, in the plant’s vascular system and on the surface of infected leaves, respectively. As our recent research show, both conidia types secrete a different set of molecules cumulating in spore-type specific leaf infection strategies (Nordzieke et al 2019). Prominent among the differentially secreted molecules are falcate conidia-derived mycosporines, potent self-inhibitors of germination.

Mycosporines are UV-absorbing small molecules closely related to mycosporine amino acids (MAA) from cyanobacteria and algae. Both molecule groups share a central 4-Deoxygadusol ring to which one (mycosporines) or two (MAAs) side chains are attached. In contrast to the well-studied MAA, the biosynthesis of mycosporines as well as the role of these molecules in development and virulence is unknown.
In this project, molecular genetics and gene expression experiments are combined with plant pathogenicity assays to 1) identify mycosporine biosynthesis genes, 2) reveal the impact of mycosporines on virulence and disease spreading of C. graminicola falcate conidia, and 3) elucidate the probable role of mycosporines in shaping spore-type specificity.

References:
Nordzieke, D.E., Sanken, A., Antelo, L., Raschke, A., Deising, H.B., Pöggeler, S.: Specialized infection strategies of falcate and oval conidia of Colletotrichum graminicola, Fungal Genet Biol, 133:103276. https://doi: 10.1016/j.fgb.2019.103276 (2019)