Abstract
Trade‐offs between virulence (defined as the ability to infect a resistant host) and life‐history traits are of particular interest in plant pathogens for durable management of plant resistances. Adaptation to plant resistances (i.e., virulence acquisition) is indeed expected to be associated with a fitness cost on susceptible hosts. Here, we investigated whether life‐history traits involved in the fitness of the potato cyst nematode Globodera pallida are affected in a virulent lineage compared to an avirulent one. Both lineages were obtained from the same natural population through experimental evolution on resistant and susceptible hosts, respectively. Unexpectedly, we found that virulent lineages were more fit than avirulent lineages on susceptible hosts: they produced bigger cysts, containing more larvae and hatching faster. We thus discuss possible reasons explaining why virulence did not spread into natural G. pallida populations.
Highlights
The existence of trade-offs between life-history traits is a central concept in evolutionary biology and ecology because they may result in the wide range of species diversity that can be observed in nature
Developing a sustainable use of plant resistances requires exploring in detail the consequences of this adaptation on life-history traits strongly involved in parasite fitness that can be in trade-off with virulence
Because virulence levels from avir(8x) and vir(8x) on the one hand and avir (10x) and vir(10x) on the other hand were not significantly different; the comparisons of life-history traits between virulent and avirulent lineages were made only using 6x and 10x G. pallida lineages in order to perform the fitness cost test
Summary
The existence of trade-offs between life-history traits is a central concept in evolutionary biology and ecology because they may result in the wide range of species diversity that can be observed in nature. The increasing restrictions on pesticide use lead to the use of crop cultivars resistant to pathogens which represent an efficient, specific and environment friendly alternative strategy to control crop diseases. In this context, the overcoming of host specific resistance and the acquisition by the parasite of virulence, that is the ability to infect and multiply in host genotypes resistant to other parasite genotypes (Vanderplank 1963; Gandon and Michalakis 2002; Tellier and Brown 2007, 2009), represents an interesting case of host adaptation. Developing a sustainable use of plant resistances requires exploring in detail the consequences of this adaptation on life-history traits strongly involved in parasite fitness that can be in trade-off with virulence
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