Competition, facilitation, and niche differentiation in two foliar pathogens

Area of Science:

• Plant pathology
• Microbial ecology
• Plant-pathogen interactions

Background:

• Plant leaves exhibit age-related resistance to pathogens.
• Puccinia triticina is an obligate biotroph, while Pyrenophora tritici-repentis is a facultative saprophyte.
• Interspecific competition influences pathogen dynamics on host plants.

Purpose of the Study:

• To investigate the competitive interactions between Puccinia triticina and Pyrenophora tritici-repentis.
• To determine how leaf age and host genotype affect pathogen competition.
• To understand the impact of inoculation timing on competitive outcomes.

Main Methods:

• Studied competition in three wheat (Triticum aestivum) genotypes with differential resistance.
• Assessed pathogen sporulation and niche overlap in older and younger leaves.
• Manipulated inoculation order (pre-interaction, simultaneous, post-interaction) for both pathogens.

Main Results:

• Pyrenophora tritici-repentis was a stronger competitor than Puccinia triticina across tested conditions.
• Both pathogens produced more spores when inoculated first or simultaneously compared to last.
• Puccinia sporulation was significantly reduced when Pyrenophora had high sporulation rates, indicating competitive exclusion.

Conclusions:

• Leaf age and inoculation timing are critical factors modulating plant pathogen competition.
• Facultative saprophytes like Pyrenophora may possess competitive advantages over obligate biotrophs like Puccinia.
• Understanding these interactions is vital for predicting disease dynamics and developing effective disease management strategies.