Progress in elucidating the molecular basis of the host plant - Aspergillus flavus interaction, a basis for devising strategies to reduce aflatoxin contamination in crops

Understanding the complex interrelationships of plant and fungal gene products during the host plant Aspergillus flavus interaction is key in developing strategies to interrupt the aflatoxin contamination process. Fungal processes necessary for invasion of the plant and production of aflatoxin can be broken down into three categories: 1) cell wall degradation (cellulases, pectinases, amylases, and proteinases), 2) fungal development (cell wall synthesis and conidiophore and conidial formation), and 3) aflatoxin biosynthesis and regulation. Fungal expressed sequence tag (EST) projects have led to a rapid expansion in the number of candidate genes governing the processes involved in invasion of the plant and aflatoxin contamination. Plant factors have been discovered through the use of proteomics and natural product chemistry that may influence fungal processes involved in invasion and aflatoxin contamination. These factors can also be divided into three categories: 1) seed proteins/inhibitors of fungal cell wall degrading enzymes, 2) seed/kernel natural products that may influence fungal growth and/or aflatoxin synthesis, and 3) plant stress-responsive proteins. If the interaction between the plant and the fungus can be better understood through use of proteomics, genomics, and natural product chemistry, particularly in how plant factors may influence fungal processes contributing to virulence and aflatoxin contamination, this information could accelerate development of breeding through marker selection and/or gene insertion technologies for enhancing host plant resistance.