Metabolic Diversity and Novelties in the Oomycetes

Abstract

The eukaryotic microbes called oomycetes include many important saprophytes and pathogens, with the latter exhibiting necrotrophy, biotrophy, or obligate biotrophy. Understanding oomycete metabolism is fundamental to understanding these lifestyles. Genome mining and biochemical studies have shown that oomycetes, which belong to the kingdom Stramenopila, secrete suites of carbohydrate- and protein-degrading enzymes adapted to their environmental niches and produce unusual lipids and energy storage compounds. Despite having limited secondary metabolism, many oomycetes make chemicals for communicating within their species or with their hosts. Horizontal and endosymbiotic gene transfer events have diversified oomycete metabolism, resulting in biochemical pathways that often depart from standard textbook descriptions by amalgamating enzymes from multiple sources. Gene fusions and duplications have further shaped the composition and expression of the enzymes. Current research is helping us learn how oomycetes interact with host and environment, understand eukaryotic diversity and evolution, and identify targets for drugs and crop protection chemicals.

Keywords: evolution; gene duplication; gene fusion; horizontal gene transfer; pathogenesis; stramenopile.