Leaf functional traits and pathogens: Linking coffee leaf rust with intraspecific trait variation in diversified...

Area of Science:

• Ecology
• Plant Biology
• Agricultural Science

Background:

• Intraspecific functional trait variation is key to plant adaptation to environmental changes.
• Plant pathogens are significant drivers of plant demography and diversity, yet their impact on trait variation is understudied.
• Understanding plant-pathogen trait relationships is crucial for a realistic view of global functional trait patterns.

Purpose of the Study:

• To investigate how leaf intraspecific trait variability (ITV) in *Coffea arabica* cv. Caturra responds to coffee leaf rust (CLR) severity.
• To determine the relationship between leaf functional traits and foliar disease severity in a coffee agroforestry system.
• To explore shifts in functional trait relationships due to increased disease prevalence.

Main Methods:

• Quantified coffee leaf rust (CLR) severity in *Coffea arabica* cv. Caturra.
• Measured key leaf functional traits within different canopy strata under contrasting management conditions.
• Analyzed the correlation between CLR severity and leaf trait values within plant canopy strata.

Main Results:

• Significant intraspecific trait variability (ITV) was observed, influenced by shade tree treatment and leaf position.
• CLR severity increased with resource-conserving trait values within a canopy stratum.
• Diseased coffee leaves exhibited greater resource-acquiring trait values compared to healthy leaves.

Conclusions:

• Leaf traits are correlated with foliar disease severity in coffee, demonstrating a direct plant-pathogen interaction.
• Functional trait relationships and syndromes shift in response to increased disease prevalence in this plant-pathogen system.
• Pathogens play a vital role in shaping global functional trait variation, necessitating their inclusion in trait relationship studies.