Plant disease and climate change: Perspectives from the genome and the ecosystem

No sweeping prediction about the effects of climate change on plant disease can be made, since the effects of change are difficult to generalize. Many pathogens benefit from higher precipitation rates and from temperature within a preferred range, but the timing of particular climatic conditions can be critical. Plant disease epidemics are probably best understood in agricultural systems, where it has been suggested that the effects of climate change will be primarily to shift where particular crop species are grown. The limiting factor for plant pathogen success in natural systems during climate change may be the ability of pathogen populations to adapt. Rapid microevolution is supported in microorganisms by short generation times and large populations, but the dominant asexual reproduction of some plant pathogens may slow adaptation. Plant disease ecology has a long history of incorporating information about the presence of plant genes that confer resistance, since it is often a small number of genes that determine whether infection can occur. With the availability of new genomic and other ‘omic’ tools, it’s possible to incorporate a broader range of information about plant phenotypic resistance, such as induced or acquired resistance, in ecological studies. Plant responses to climate stressors may enhance or reduce disease resistance, depending on the pathways and inherent trade-offs. At the ecosystem level, global trends toward more rapid movement of organisms may result in greater risk of regional effects of introduced plant diseases, such as the loss of chestnuts in the eastern US to chestnut blight. Even if the primary effect on agricultural systems is to shift where particular crop species are grown, this may result in important changes in processes such as nutrient loss from agriculture to surrounding ecosystems.