Epidemiology and Population Biology of Pseudoperonospora cubensis: A Model System for Management of Downy Mildews

Abstract

The resurgence of cucurbit downy mildew has dramatically influenced production of cucurbits and disease management systems at multiple scales. Long-distance dispersal is a fundamental aspect of epidemic development that influences the timing and extent of outbreaks of cucurbit downy mildew. The dispersal potential of Pseudoperonospora cubensis appears to be limited primarily by sporangia production in source fields and availability of susceptible hosts and less by sporangia survival during transport. Uncertainty remains regarding the role of locally produced inoculum in disease outbreaks, but evidence suggests multiple sources of primary inoculum could be important. Understanding pathogen diversity and population differentiation is a critical aspect of disease management and an active research area. Underpinning advances in our understanding of pathogen biology and disease management has been the research capacity and coordination of stakeholders, scientists, and extension personnel. Concepts and approaches developed in this pathosystem can guide future efforts when responding to incursions of new or reemerging downy mildew pathogens.

Population structure and migration of the Tobacco Blue Mold Pathogen, Peronospora tabacina, into North America and Europe

“…We analysed the genetic structure of populations of Peronospora tabacina from a global collection of isolates from 11 countries in T A B L E 2 (Continued) High levels of genetic variation were found among populations of P. tabacina when DNA from allelic regions of several loci was cloned and sequenced in our work. Other downy mildews such as cucurbit downy mildew also exhibit high levels of genetic diversity in the United States in Florida and North Carolina (Choi, Thines, Han, & Shin, 2011;Ojiambo, Gent, Quesada-Ocampo, Hausbeck, & Holmes, 2015). Several possible mechanisms could explain the high genetic variation observed in the blue mold pathogen.…”

Pseudoperonospora cubensis virulence and pathotype structure in Kazakhstan

“…Globally, populations of P. cubensis have changed and new virulent pathotypes have emerged (Lebeda et al ., , ; Cohen et al ., ; Kitner et al ., ; Ojiambo et al ., ). New pathotypes not only cause severe epidemics but substantially limit production of commercial cucurbit varieties and hybrids.…”

The Lambert W function in ecological and evolutionary models

“…Scattered applications of W can be found in existing ecological and evolutionary models: examples include theoretical population genetics (Yu, Etheridge & Cuthbertson 2010;Santiago 2015), estimating predator functional responses (McCoy & Bolker 2008), maximum sustainable yields in fisheries management (White & Kendall 2007), modelling coexistence of microbial strains (Sinclair 2014), linking molecular evolution to life history (Lehtonen & Lanfear 2014) and disease dynamics and management (Molina & Earn 2015;Ojiambo et al 2015). At the same time, examples can be found where the Lambert W function could be used for deriving an explicit solution and to possibly gain further insight, but was not applied; the Lambert W function remains comparatively unknown.…”