Name: Dr. Baozhu Guo
Title: Research Plant Pathologist
Research: Molecular genetic studies of corn earworm resistance and development of markers for use in marker-assisted selection. Mechanisms of resistance and genetic studies of resistance to aflatoxin contamination in corn and peanuts.
Support Staff: Ernest Harris
Address: Crop Protection and Management Research Unit
USDA-ARS
P.O. Box 748
Tifton, GA 31793-0748
Phone: 229-387-2375
FAX: 229-387-2321
E-Mail: BGuo@tifton.usda.gov
Education: B.S. Shanzi Agricultural University
M.S. University of Kentucky
Ph.D. Louisiana State University
CRIS Project Title: Integration of Alternative Pest Management Strategies for the Management of Insects and Aflatoxin Contamination in the Southeastern Coastal Plain
Research Goals: Apply advanced biotechnology to identify genes for resistance to insects and Aspergillus flavus/aflatoxin production in corn and peanut; develop markers associated with the resistance to assist in the transfer and selection through molecular mapping, molecular genetic studies, and characterization of the biochemical and molecular bases for quantitative trait loci involved in resistance; and mapping QTLs for resistance to A. flavus and other pests.
Major Accomplishments:
Documented that the mechanisms of resistance to aflatoxin formation in corn are physical factors in the intact pericarp and sub-pericarp and biochemical factors (anti-fungal proteins) within kernels.
Demonstrated that wax on kernel surfaces of corn population GT-MAS:gk can restrict entry of the fungus Aspergillus flavus, and internal factors may restrict growth of the fungus or aflatoxin biosynthesis within kernels.
Documented that Aspergillus flavus can produce cell wall-degrading enzyme cutinase, which may play a role in the invasion of corn kernels or colonization of silks before infection of kernels.
Demonstrated that the susceptibility of corn genotypes to aflatoxin formation was reduced when kernels were incubated at germination condition.
Demonstrated that the germination-associated resistance phenomenon was linked to induction of some antifungal protein, such as zeamatin and ribosome-inactivating-protein (RIP). Further, tissue localization showed that these induced anti-fungal proteins formed a biochemical defense zone.
Demonstrated that silk browning was closely associated with silk maysin concentrations and antibiosis in corn in 4 F2 populations. Silk browning could be used as selection marker.
Mapped major QTLs/genes, p1 and a1, linked with silk maysin concentration in corn. Demonstrated the epistatic effect of p1 and a1 loci on silk maysin in F2 of SC102 x B31857.
Documented that the quantitative effects of loci p1 and a1 on the concentrations of maysin, apimaysin, methoxymaysin, and chlorogenic acid in maize silk in F2 of GE37 x 565.
Mapped the QTLs linked to aflatoxin formation and husk coverage and tightness in F3 families of GT-A1 x GT119 and GT-A2 x 9-54C.
Demonstrated that corn hybrids with drought tolerance may have reduced aflatoxin contamination.