Fitopatógenos do gênero Pythium: polífagos e destrutivos em ambientes úmidos

Abstract

Pythium is one of the microorganisms of greatest agricultural interest in the world. Most of the species of this genus are natural inhabitants of the soil with a high capacity for surviving even in the absence of hosts, either as saprophytes or by means of resistance structures. Pythium species can cause plant diseases, such as seedling damping off and leaf blights, as well as root, stem, branch and fruit rots. Several environmental factors differentially modulate the behavior of Pythium species, especially humidity, temperature and soil pH. Most species of this genus are polyphagous and produce resistance structures, what makes difficult to manage the diseases they cause. In this sense, management should be based mainly on the adoption of preventive measures, in order to create a less favorable environment for spread, establishment, multiplication and infection. The genus Pythium was created by Pringsheim in 1858. Since then, much has been added in terms of knowledge about the etiology, epidemiology and management of the diseases caused by this pathogen. With the development and improvement of molecular biology techniques, there was an astonishing advance in understanding the biology, physiology and genetic variability of the genus and its species, which contributed to the phylogenetic studies involving Pythium spp. The demand for new research in these areas of study will always be in vogue, as organisms are subject to constant evolutionary processes. This review presents the state of the art on the advances in studies involving the genus Pythium with a view to fostering new lines of research aimed at the ultimate goal of controlling the diseases caused by this pathogenic oomycete.