EC Accepts, published online ahead of print on 12 June 2009

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Eukaryotic Cell doi:10.1128/EC.00335-08
Copyright (c) 2009, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.

The roles of the glyoxylate and methylcitrate cycles in sexual development and virulence in the cereal pathogen Gibberella zeae

Seung-Ho Lee, You-Kyoung Han, Sung-Hwan Yun^*, and Yin-Won Lee^*

School of Agricultural Biotechnology and Centers for Fungal Pathogenesis and Agricultural Biomaterials, Seoul National University, Seoul 151-921, Korea; Horticultural Environment Division, National Horticultural Research Institute, Rural Development Administration, Suwon 440-706, Korea; Department of Medical Biotechnology, Soonchunhyang University, Asan 336-745, Korea

^* To whom correspondence should be addressed. Email: sy14{at}sch.ac.kr. lee2443{at}snu.ac.kr.

The glyoxylate and methylcitrate cycles are involved in the metabolism of two- or three-carbon compounds in fungi. To elucidate the role(s) of these pathways in Gibberella zeae, which causes head blight in cereal crops, we focused on the functions of G. zeae orthologs (GzICL1 and GzMCL1) of the genes that encode isocitrate lyase (ICL) and methylisocitrate lyase (MCL), respectively, a key enzyme in each cycle. The deletion of GzICL1 (GzICL1) caused defects in growth on acetate and in perithecium (sexual fruiting body) formation, but not in virulence on barley and wheat, indicating that GzICL1 acts as the ICL of the glyoxylate cycle and is essential for self-fertility in G. zeae. In contrast, the GzMCL1 strains failed to grow on propionate but exhibited no major changes in other traits, suggesting that GzMCL1 is required for the methylcitrate cycle in G. zeae. Interestingly, double-deletion of both GzICL1 and GzMCL1 caused significantly reduced virulence on host plants, indicating that both GzICL1 and GzMCL1 have redundant functions for plant infection in G. zeae. Thus, both GzICL1 and GzMCL1 may play important roles in determining major mycological and pathological traits of G. zeae by participating in different metabolic pathways for the use of fatty acids.