Detection, quantification, and characterization of airborne Aspergillus flavus within the corn canopy

Area of Science:

• Plant Pathology
• Mycology
• Agricultural Science

Background:

• Aflatoxin contamination in corn is a significant agricultural concern.
• Airborne conidia of Aspergillus flavus are a primary infection route for developing corn kernels.

Purpose of the Study:

• To investigate the abundance, dynamics, and aflatoxin-producing potential of airborne Aspergillus flavus within corn canopies.
• To assess the genetic diversity of airborne A. flavus populations and identify potential biocontrol strain haplotypes.

Main Methods:

• Field experiments were conducted over two growing seasons in Texas and Mississippi.
• Airborne conidia density was monitored at various heights and times within the corn canopy.
• Aflatoxigenicity and genetic diversity of isolated A. flavus strains were analyzed using molecular techniques.

Main Results:

• No significant diurnal changes or height-dependent effects on conidial density were observed.
• Airborne A. flavus populations increased significantly through the growing season, with a >20-fold rise from July to August.
• Median aflatoxigenicity was 50-fold higher in Texas than Mississippi; highly aflatoxigenic S-morphotypes were prevalent in Mississippi.
• High genetic diversity was found, with 76 unique haplotypes, and biocontrol strain haplotypes were detected in both states.

Conclusions:

• Airborne A. flavus populations within corn canopies are dynamic and increase with crop development.
• Significant regional differences in aflatoxigenicity exist, with Texas showing higher potential than Mississippi.
• The genetic diversity and presence of biocontrol haplotypes suggest complex population dynamics and potential for biological control strategies.