Perturbation of maize metabolism influences susceptibility to Ustilago maydis
M. KRETSCHMER (1), D. Croll (1), J. Kronstad (1) (1) Michael Smith Laboratories, The University of British Columbia, Canada

Metabolic adaptation of biotrophic fungi to the host environment is a critical aspect of disease. We used RNA-Seq to analyze the transcriptional response of maize to U. maydis infection and identified changes that indicate metabolic shifts during disease. This analysis revealed modifications in transcriptional regulation (e.g., floral induction), metabolism (e.g., sucrose, starch, amino acids and secondary metabolites), and chloroplast function. These changes were relevant because disease symptoms were altered in an id1 mutant with defects in the vegetative to reproductive transition, in the su1 mutant with altered starch metabolism, and in the why1 mutant with defective chloroplast function. The relevance of specific metabolic functions was also established by assaying disease in plants treated with silver nitrate and the herbicides glufosinate and glyphosate. Overall, we found that specific regulatory and metabolic changes influenced host susceptibility. In particular, altered carbohydrate metabolism promoted resistance while loss of chloroplast functions or inhibition of EPSP-synthase by glyphosate, or glutamine synthase by glufosinate, increased disease severity. We propose that these functions alter carbon/nitrogen allocation to promote fungal growth or to influence plant defence. These studies reveal key metabolic aspects critical for biotrophic adaptation in the maize-U. maydis interaction.

Abstract Number: P9-270
Session Type: Poster