Abstract
Genetic, physiological and physical homogenization of agricultural landscapes creates ideal environments for plant pathogens to proliferate and rapidly evolve. Thus, a critical challenge in plant pathology and epidemiology is to design durable and effective strategies to protect cropping systems from damage caused by pathogens. Theoretical studies suggest that spatio‐temporal variation in the diversity and distribution of resistant hosts across agricultural landscapes may have strong effects on the epidemiology and evolutionary potential of crop pathogens. However, we lack empirical tests of spatio‐temporal deployment of host resistance to pathogens can be best used to manage disease epidemics and disrupt pathogen evolutionary dynamics in real‐world systems. In a field experiment, we simulated how differences in Brassica napus resistance deployment strategies and landscape connectivity influence epidemic severity and Leptosphaeria maculans pathogen population composition. Host plant resistance, spatio‐temporal connectivity [stubble loads], and genetic connectivity of the inoculum source [composition of canola stubble mixtures] jointly impacted epidemiology (disease severity) and pathogen evolution (population composition). Changes in population composition were consistent with directional selection for the ability to infect the host (infectivity), leading to changes in pathotype (multilocus phenotypes) and infectivity frequencies. We repeatedly observed decreases in the frequency of unnecessary infectivity, suggesting that carrying multiple infectivity genes is costly for the pathogen. From an applied perspective, our results indicate that varying resistance genes in space and time can be used to help control disease, even when resistance has already been overcome. Furthermore, our approach extends our ability to test not only for the efficacy of host varieties in a given year, but also for durability over multiple cropping seasons, given variation in the combination of resistance genes deployed.
Highlights
In modern agriculture, the implementation of genetic, technological and agronomic innovations have enabled large increases in productivity (Pretty, 2008)
Any strategy that reduces the size of epidemics and the transfer of inoculum between seasons should reduce the effective size of pathogen populations, limit evolutionary potential and increase resistance durability (Bousset & Chèvre, 2012, 2013; McDonald & Linde, 2002; Zhan, Thrall, & Burdon, 2014; Zhan, Thrall, Papaïx, Xie, & Burdon, 2015)
We used the fungal pathogen L. maculans to investigate how disease severity and pathogen population genetic structure vary in relation to inoculum load, levels of adaptation present in an inoculum source and host resistance
Summary
The implementation of genetic, technological and agronomic innovations have enabled large increases in productivity (Pretty, 2008). One general consequence of modernization has been simplification of the genetic, physiological and spatial elements of agricultural landscapes. Such ecological homogeneity facilitates the invasion, adaptation and proliferation of plant pathogens within agroecosystems. A critical challenge in plant pathology and epidemiology is to design and implement strategies to better protect agricultural crops from rapidly evolving pathogens. Any strategy that reduces the size of epidemics and the transfer of inoculum between seasons should reduce the effective size of pathogen populations, limit evolutionary potential and increase resistance durability (Bousset & Chèvre, 2012, 2013; McDonald & Linde, 2002; Zhan, Thrall, & Burdon, 2014; Zhan, Thrall, Papaïx, Xie, & Burdon, 2015)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
