Applied and Environmental Microbiology, April 2002, p. 1647-1651, Vol. 68, No. 4
0099-2240/02/$04.00+0 DOI: 10.1128/AEM.68.4.1647-1651.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.
Proline Reverses the Abnormal Phenotypes of Colletotrichum trifolii Associated with Expression of Endogenous Constitutively Active Ras
Stephen D. Memmott, Young-sil Ha, and Martin B. Dickman*
Department of Plant Pathology, University of Nebraska, Lincoln, Nebraska 68583-0722
Received 6 August 2001/
Accepted 11 January 2002
Colletotrichum trifolii is the causative organism of alfalfa anthracnose. We previously cloned and characterized the small prototypical G protein, Ras, of C. trifolii, which is involved in the signaling pathways that mediate interaction between the pathogen and its host. Transformants expressing constitutively active forms of Ras have growth medium-dependent phenotypes. In nutrient-rich media (e.g., yeast extract and peptone), the phenotype of the transformants was indistinguishable from that of the wild type. However, during nutrient starvation, the transformants lose polarity, have distended hyphae, and fail to sporulate and produce appressoria. Since peptone caused the phenotype to revert, amino acids were tested singly and in combination to identify the responsible amino acid(s). We found that 1.6 mM proline in the medium reverses the constitutively active Ras phenotype.
* Corresponding author: Mailing address: Department of Plant Pathology, University of Nebraska, Lincoln, NE 68583-0722. Phone: (402) 472-2849. Fax: (402) 472-2853. E-mail: mdickman{at}unlnotes.unl.edu.
Applied and Environmental Microbiology, April 2002, p. 1647-1651, Vol. 68, No. 4
0099-2240/02/$04.00+0 DOI: 10.1128/AEM.68.4.1647-1651.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.
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Copyright © 2002 by the American Society for Microbiology. All rights reserved.