Do plant pathogens prefer seedlings? Variation in age-specific infectivity across pathogen genotypes

Area of Science:

• Plant pathology
• Evolutionary biology
• Epidemiology

Background:

• Juveniles in plant and animal species are typically more vulnerable to pathogens than adults.
• Research is exploring the evolution of age-specific resistance and the maintenance of juvenile susceptibility.
• Pathogen infectivity often shows age-specific patterns, with higher rates in juveniles.

Purpose of the Study:

• To investigate if age-specific infectivity varies among pathogen genotypes within Microbotryum lychnidis-dioicae.
• To determine if pathogen genotype and host genotype interactions affect infection risk at different host ages.
• To understand the resistance mechanisms in juvenile versus adult Silene latifolia.

Main Methods:

• Inoculation of four Silene latifolia host genotypes with five Microbotryum lychnidis-dioicae pathogen genotypes.
• Experiment conducted across two host ages: seedling (juvenile) and adult.
• Analysis of significant interactions between pathogen genotype, host genotype, and host age.

Main Results:

• Significant interactions between pathogen genotype and host age were observed, indicating evolving age-specific infectivity.
• Pathogen × host genotype interactions significantly influenced infection risk in juvenile and vegetative adult hosts.
• Infection risk in reproductive adults was mainly determined by main effects of pathogen and host genotypes.

Conclusions:

• Age-specific infectivity is an evolvable trait in Microbotryum lychnidis-dioicae.
• Specific immunological interactions likely mediate resistance in juvenile and non-reproductive adult plants.
• General resistance mechanisms, potentially physical barriers, may protect reproductive adult plants.