Quantitative interactions: the disease outcome of Botrytis cinerea across the plant kingdom

Abstract

Botrytis cinerea is a fungal pathogen that causes necrotic disease on more than a thousand known hosts widely spread across the plant kingdom. How B. cinerea interacts with such extensive host diversity remains largely unknown. To address this question, we generated an infectivity matrix of 98 strains of B. cinerea on 90 genotypes representing eight host plants. This experimental infectivity matrix revealed that the disease outcome is largely explained by variations in either the host resistance or pathogen virulence. However, the specific interactions between host and pathogen account for 16% of the disease outcome. Furthermore, the disease outcomes cluster among genotypes of a species but are independent of the relatedness between hosts. When analyzing the host specificity and virulence of B. cinerea, generalist strains are predominant. In this fungal necrotroph, specialization may happen by a loss in virulence on most hosts rather than an increase of virulence on a specific host. To uncover the genetic architecture of Botrytis host specificity and virulence, a genome-wide association study (GWAS) was performed and revealed up to 1492 genes of interest. The genetic architecture of these traits is widespread across B. cinerea genome. The complexity of the disease outcome might be explained by hundreds of functionally diverse genes putatively involved in adjusting the infection to diverse hosts.

Identification of genetic loci in lettuce mediating quantitative resistance to fungal pathogens

“…Although the S. sclerotiniorum isolate used here was initially obtained from field grown lettuce, our analysis was restricted to single isolates of both pathogens. Previous studies using B. cinerea have indicated that there is a high level of isolate-specificity to quantitative resistance loci (Zhang et al 2016 ) and data on disease outcome using 98 B. cinerea isolates and 90 genotypes of eight plant hosts (including lettuce) demonstrated a much greater impact on lesion size from the B. cinerea isolate (40–71%) than the host genotype (3–8%) (Caseys et al 2021 ). Similarly, in B. napus both pathotype-specific and pathotype-independent resistance against S. sclerotiorum has been identified (Neik et al 2017 ).…”

Combined reference-free and multi-reference approaches uncover cryptic variation underlying rapid adaptation in microbial pathogens

“…SNP-based GWAS based on a single reference genome dataset have been successful in describing the genetic basis of complex pathogen traits (Mohd-Assaad et al 2016; Pereira et al 2020b; Caseys et al 2021; Singh et al 2021). By expanding the number of reference genome SNP datasets used for GWAS, we identified substantially more independent loci than what was previously identified using the same phenotype dataset (Dutta et al 2021).…”

Identification of genetic loci in lettuce mediating quantitative resistance to fungal pathogens

“…Although the S. sclerotinia isolate used here was initially obtained from field grown lettuce, our analysis was restricted to single isolates of both pathogens. Previous studies using B. cinerea have indicated that there is a high level of isolate-specificity to quantitative resistance loci (Zhang et al 2016) and data on disease outcome using 98 B. cinerea isolates and 90 genotypes of eight plant hosts (including lettuce) demonstrated a much greater impact on lesion size from the B. cinerea isolate (40-71%) than the host genotype (3-8%)(Caseys et al 2021). Similarly, in B. napus both pathotype-specific and pathotype-independent resistance against S. sclerotiorum has been identified (Neik et al 2017).…”