Physiological and Molecular Plant Pathology 70 (2007) 88–95 Comparison of fungal growth and production of extracellular pectin lyase activity by pathogenic and non-pathogenic races of Colletotrichum lindemuthianum cultivated under different conditions Lorena Herna´ndez-Silva a , Carlos Pin˜o´n-Escobedo a , Horacio Cano-Camacho b , Ma. Guadalupe Zavala-Pa´ramo b , Ismael Acosta-Rodrı´guez c , Everardo Lo´pez-Romero a,à a Instituto de Investigacio´n en Biologı´a Experimental, Facultad de Quı´mica, Universidad de Guanajuato, Apartado Postal No. 187, Guanajuato, Gto. 36000, Mexico b Centro Multidisciplinario de Estudios en Biotecnologı´a, Universidad Michoacana de San Nicola´s de Hidalgo, Apartado Postal No. 53, Administracio´n Chapultepec, Morelia, Mich. 262, Mexico c Facultad de Ciencias Quı´micas, Universidad Auto´noma de San Luis Potosı´, San Luis Potosı´, S.L.P. 78320, Mexico Accepted 19 July 2007 Abstract A comparison between pathogenic (1472) and non-pathogenic (0) races of Colletotrichum lindemuthianum revealed significant differences in terms of growth and production of extracellular pectin lyase activity on different carbon and nitrogen sources in liquid culture. Race 1472 grew faster in media containing glucose or polygalacturonic acid. On the latter, both races secreted comparable levels of pectin lyase activity but race 1472 produced approximately twice the amount of mycelia. On 92%-esterified pectin, race 1472 produced the highest activity detected in this study and this was about two-fold higher as compared with race 0. Cell walls isolated from Phaseolus vulgaris hypocotyls and to a lower degree cellulose sustained growth of both races but induced PNL only in the pathogenic race. On xylan, both races produced substantial and similar enzyme levels but this polysaccharide sustained growth of race 1472 only. Compared with race 1472, race 0 grew much slower on glutamate but produced similar amounts of mycelia in other nitrogen sources. On ammonium chloride, race 1472 produced a five-fold higher activity than race 0. Differences are discussed in terms of their possible relevance in fungal pathogenesis. r 2007 Elsevier Ltd. All rights reserved. Keywords: Colletotrichum lindemuthianum; Pathogenic race; Non-pathogenic race; Growth; Pectin lyase activity; Induction 1. Introduction Anthracnose, a destructive disease of bean, is produced by the ascomycete fungus Colletotrichum lindemuthianum [1]. In addition to its relevance as an economically important phytopathogen, this organism and its host (Phaseolus vulgaris) represent a convenient model to study the physiological and molecular bases of plant–pathogen interaction [2]. C. lindemuthianum is an intracellular hemibiotrophic pathogen. After penetration of a host epidermal cell, an infection vesicle is formed and the fungus extends into adjacent cells by producing large primary hyphae which invaginate without penetrating the host cell membrane, thus persisting as a biotrophic interaction. Once a large area of the plant tissue has been colonized, necrotrophic hyphae develop [3] and this step closely correlates with the production of a number of host cell-wall-degrading enzymes [4,5]. It has been reported that pectin and pectate lyases (PLs), polygalacturonases (PGs), pectin-methyl este- rases and rhamnogalacturonases are the first cell-wall- ARTICLE IN PRESS www.elsevier.com/locate/pmpp 0885-5765/$ - see front matter r 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.pmpp.2007.07.005 Abbreviations: FEM, filtered extracellular medium; PDA, potato dextrose agar; PG, polygalacturonase; PGA, polygalacturonic acid; PL, pectate lyase; PNL, pectin lyase; UUE, unsaturated uronic esters à Corresponding author. Tel.: +52 473 73 20006x8156; fax: +52 473 73 20006. E-mail address: everlope@quijote.ugto.mx (E. Lo´pez-Romero).