Consequences of seed transmission for plant virus emergence.

Plant virus emergence is a major threat for agricultural production and for the preservation of biodiversity in wild ecosystems. This process is determined by genetic and ecological factors and, among the latter, one of the most important is the chance for the virus to encounter susceptible plant populations. Seed transmission has a great potential to facilitate such encounters: from allowing plant viruses to persist locally over unfavorable conditions such as the absence of susceptible hosts, to mediate long range dissemination to reach distant plant populations that could not otherwise be invaded. Here, we review current knowledge on the relationship between plant virus seed transmission and emergence, and on its consequences for the epidemiology of these pathogens. We start by setting up a conceptual framework based on mathematical modelling. Then, we summarize experimental and empirical evidence supporting the central role of seed transmission for initiating damaging plant virus-induced disease epidemics, at different geographical scales and in wild and cultivated plant populations. Finaly, we explore current methodologies to limit the emergence of plant viruses associated with seed transmission. Considering these studies, we propose avenues for future research on this subject.