Comparative epidemiology of zoosporic plant pathogens

Abstract

Loss of zoospores has happened independently several times in different phylogenic lines and has, it is claimed, no major phylogenetic significance. But whether or not, how, and under which conditions plant pathogens retain the ability to produce motile asexual spores has fundamental importance from an ecological and epidemiological perspective. Recent molecular investigations of the early evolution of fungi and oomycetes are shedding light on the issue of zoospore loss in organisms able to cause plant diseases. Zoospore loss may have accompanied the development of new forms of dispersal adapted to the terrestrial environment, or the simplification processes which often follow the shift to parasitic or biotrophic life-forms. In this review we consider hybridisation events between Phytophthora species, long distance dispersal of oomycetes, sporangia and zoospore survival, direct and indirect infection processes and newly observed sporulating structures. These aspects are all relevant features for an understanding of the epidemiology of zoosporic plant pathogens. Disease management should not be based on the presumption that the zoosporic stage is a weak link in the life cycle. Oomycete plant pathogens show remarkable flexibility in their life cycles and ability to adapt to changing environmental circumstances.

Cucurbit downy mildew (Pseudoperonospora cubensis)—biology, ecology, epidemiology, host-pathogen interaction and control

“…Current advances on comparative ecology and epidemiology of zoosporic plant pathogens were summarized by Jeger and Pautasso (2008). We focus here on the most important ecological factors that influence the epidemiology of P. cubensis.…”

Evolution of Qol resistance in Plasmopara viticola oospores

“…Berl. and De Toni is a serious disease in climates characterized by moderate temperatures and frequent rainfall in spring and summer (Gilles 2004;Jeger and Pautasso 2008). These conditions occur in different viticultural area and years leading to severe epidemics, as it was observed in the past few years first in southern and then in northern Italy.…”

Assessing Phytophthora Zoospore Activity to Enhance Disease Management and Promote Ecological Surveillance of Chestnut Ink Disease

“…It occurs within minutes (Walker and Van West, 2007) and reveals the rapid capacity of Phytophthora to adapt to drastic environmental changes. As was stated by Jeger and Patausso (2008) zoospore behaviour is essential in order to understand and predict epidemic development.…”

“…On the contrary, P. cinnamomi is considered as one of the most ubiquitous and destructive plant pathogens, the most widely distributed and the species with the largest host range (Zentmyer, 1980). Liquid environments are necessary for the formation of sporangia and zoospore discharge, dispersal and active swimming to reach the roots (Hardham, 2001(Hardham, , 2005Van West et al, 2003;Walker and Van West, 2007;Jeger and Patausso, 2008). The primary role of zoospores is the transmission of the pathogen (Walker and Van West, 2007 68 which are single nucleated and wall-less cells, should not be considered a weak link in the life cycle of zoosporic plant pathogens.…”