Interaction Types Produce Distinct Microscopic Phenotypes in the Exserohilum turcicum-Maize/Sorghum Pathosystem

Area of Science:

• Plant Pathology
• Molecular Plant-Microbe Interactions
• Crop Science

Background:

• Exserohilum turcicum causes significant diseases in maize and sorghum.
• Host specificity and gene-for-gene resistance are key factors in E. turcicum interactions.
• Understanding early infection steps is crucial for developing resistant crop varieties.

Purpose of the Study:

• To characterize and compare the early infection processes of E. turcicum in adapted and unadapted host interactions.
• To investigate the role of host-specific strains and resistance genes in disease development.
• To identify potential novel resistance mechanisms by analyzing pathogen behavior in non-host scenarios.

Main Methods:

• Quantitative analysis of early colonization phenotypes using epifluorescence and confocal fluorescence microscopy.
• Comparative study of three interaction types: unadapted, adapted-susceptible, and adapted-resistant.
• Characterization of progeny strains for host adaptation and fitness.

Main Results:

• Significant differences in infection steps were observed between adapted and unadapted interactions.
• Unadapted interactions showed increased appressoria formation and host cell death (hypersensitive response).
• Adapted-susceptible interactions led to greater xylem and mesophyll colonization compared to other types.

Conclusions:

• Unadapted host interactions provide valuable insights into E. turcicum host specificity.
• Studying pathogen behavior on non-hosts can reveal novel crop resistance mechanisms.
• Dual host adaptation in E. turcicum strains occurs without a fitness cost.