Maize Glyoxalase I regulate methylglyoxal levels, a stress signal molecule sensed by Fusarium verticillioides

TURRA GINO; FAUGUEL CAROLINA; PRESELLO DANIEL; ANDREO CARLOS; CAMPOS BERMUDEZ VALERIA

Congreso; XXX Reunion Argentina de Fisiologia Vegetal; 2014

Fusarium verticillioides is the most common fungal disease on maize ears. It not only reduces yield and quality of maize crops, but also produces fumonisins, which are toxic for both humans and animals. The expression of Glyoxalase I (GlxI), a metalloenzyme involved in detoxification of methyglyoxal (MG), is upregulated in moderately resistant lines compared with susceptible ones. MG is a cytotoxic byproduct of metabolism that increases its levels during stress conditions. Although several studies describe an association between this enzyme levels with abiotic stress tolerance, only a few reports analyze its role in biotic stress. In this study, maize GlxI was cloned and expressed in Escherichia coli. Biochemical and structural characterization of this protein reveals a 32-KDa monomeric enzyme able to use either, Co2+, Ca2+, Zn2+ or Ni2+ for its catalytic activity. Additionally, we have evaluated the role of MG as stress signal, detecting effects on morphology, mycotoxin production, and the expression of fum1 and fum21 (involved in fumonisin biosynthesis) in F. verticillioides cultures. Hence, GlxI allows the plant to withstand stresses by lowering levels of MG, and we propose that such signal is also used by the fungus to increase its virulence.