ABSTRACT
In previous chapters, we have described that, in general, all living beings require polyamines for their growth and development. It is no surprise, then, that synthesis of polyamines may be considered a target for the selective inhibition of growth or some of the adverse effects of different processes, such as virulence or cancer. For example, in plants, putrescine, the precursor of higher polyamines, is synthesized by direct decarboxylation of l-ornithine in a reaction catalyzed by ornithine decarboxylase (Odc) or by decarboxylation of l-arginine by arginine decarboxylase (Adc), leading to the formation of putrescine through agmatine and N-carbamoyl putrescine as intermediates. Accordingly, the alternative pathway (Adc) for the production of putrescine allows the selective inhibition of polyamine biosynthesis in plant pathogenic fungi by Odc inhibitors without affecting plant polyamine metabolism, taking into consideration that fungi utilize only the Odc pathway for putrescine biosynthesis (Valdes-Santiago et al. 2012a). Suicide Odc inhibitors such as diuoro methylornithine (DFMO) and a potent inhibitor of S-adenosylmethionine decarboxylase (Samdc), methylglyoxalbis(guanylhydrazone) (MGBG), would be the best inhibitors available to selectively block polyamine biosynthesis.
