Pattern of local adaptation to quantitative host resistance in a major pathogen of a perennial crop

Abstract

Understanding the mechanisms involved in pathogen adaptation to quantitative resistance in plants has a key role to play in establishing durable strategies for resistance deployment, especially in perennial crops. The erosion of quantitative resistance has been recently suspected in Cuba and the Dominican Republic for a major fungal pathogen of such a crop: Pseudocercospora fijiensis, causing black leaf streak disease on banana. This study set out to test whether such erosion has resulted from an adaptation of P. fijiensis populations, and to determine whether or not the adaptation is local. Almost 600 P. fijiensis isolates from Cuba and the Dominican Republic were sampled using a paired‐population sampling design on resistant and susceptible banana varieties. A low genetic structure of the P. fijiensis populations was detected in each country using 16 microsatellite markers. Cross‐inoculation experiments using isolates from susceptible and resistant cultivars were carried out, measuring a quantitative trait (the diseased leaf area) related to pathogen fitness on three varieties. A further analysis based on those data suggested the existence of a local pattern of adaptation to resistant cultivars in both of the study countries, due to the existence of specific (or genotype by genotype) host–pathogen interactions. However, neither cost nor benefit effects for adapted populations were found on the widely used “Cavendish” banana group. These results highlight the need to study specific host–pathogen interactions and pathogen adaptation on a wide range of quantitative resistance phenotypes in banana, in order to develop durable strategies for resistance deployment.

Convergent Adaptation to Quantitative Host Resistance in a Major Plant Pathogen

“…5 Genomic regions were classified in four selection-support classes (Table 4). 6 Asterisks highlighted in salmon pink indicate the methods from which the genomic regions were detected with a 1% significance threshold. The F st values highlighted in green were considered significant with a 5% significant threshold.…”

Complex adaptive architecture of quantitative resistance erosion in a plant fungal pathogen

“…More than 1 000 strains were isolated representing 14 populations with a number of isolates per population ranging between 38 and 135. The six populations sampled in 2011 had already been analyzed to investigate local adaptation to banana quantitative resistance and the underlying genetic basis in P. fijiensis (Dumartinet et al, 2019;Carlier et al, 2021b). To further describe adaptive architecture, in this study, we added eight more populations sampled in 2013 in the same locations.…”

“…However, after five to 10 years of cultivation, in both countries, erosion of resistance was reported in FHIA 18 and FHIA 21 cultivars in the field (Pérez Miranda et al, 2006;Guzmán et al, 2019). Local adaptation of P. fijiensispopulations explaining the erosion of resistance of FHIA hybrids in the two countries was demonstrated in cross-inoculation experiments (Dumartinet et al, 2019). An even more recent study based on pool sequencing (Pool-Seq) supported the existence of convergent adaptation in both resistant and susceptible cultivars in less than 10 genomic regions, suggesting oligogenic architecture underlies this adaptation (Carlier et al, 2021b).…”

Besides stem canker severity, oilseed rape host genotype matters for the production ofLeptosphaeria maculansfruiting bodies

“…Host resistance is usually described by its impact on pathogen life history traits during the epidemic phase, by e.g. infection efficiency, latent period or sporulation (Bruns et al, 2012;Delmas et al, 2016;Dumartinet et al, 2020;Leclerc et al, 2019;Bove & Rossi 2020). In short, from an epidemiological point of view, qualitative host resistance reduces the number of compatible infections whereas quantitative host resistance reduces the amplification during the epidemics (Fig.…”