Project Number: 3602-22000-015-00
Project Type: Appropriated

Start Date: Apr 02, 2007
End Date: Apr 01, 2012

Objective:
Objective 1: Analyze pathogen gene expression during disease development to identify the mechanisms of pathogenicity or virulence of fungal pathogens to maize and wheat. Sub-objective 1a. Assess the role of genes that regulate conidiation and phytotoxin synthesis during pathogenesis of maize and wheat by fungal pathogens, including Exserohilum turcicum, Cercospora zeae-maydis, and Mycosphaerella graminicola. Sub-objective 1b. Identify pathogen proteins secreted into apoplastic fluids and test whether they function as virulence factors in pathogens of maize and wheat, e.g., Exserohilum turcicum and Mycosphaerella graminicola. Sub-objective 1c. Assess the impact of mating-type gene evolution on speciation in fungal plant pathogens, including Mycosphaerella graminicola and Septoria passerinii. Objective 2: Analyze the function and chromosomal location of host genes predicted to be involved in disease resistance in wheat and maize. Sub-objective 2a. Investigate mechanisms of host-specific resistance of wheat to Mycosphaerella graminicola and of maize to Exserohilum turcicum. Sub-objective 2b. Elucidate mechanisms of non-host resistance focusing on resistance of barley to Mycosphaerella graminicola and resistance of wheat to Septoria passerinii. Sub-objective 2c. Discover closely linked markers on wheat chromosome 3BS for marker-assisted selection and eventual positional cloning of the Stb2 gene for resistance to Mycosphaerella graminicola.

Approach:
Fungal genes expressed during critical stages of pathogenesis will be identified by microarray analysis and by subtractive suppressive hybridization; involvement of selected genes, including those for phytotoxin synthesis and conidiation, will be assessed by transformation and gene disruption and silencing methods. Patterns of gene expression in resistant and susceptible genotypes of maize and wheat will be determined with microarrays composed primarily of cDNAs identified from a database of ESTs. The chromosomal location of genes for resistance to fungal pathogens will be determined by employing a variety of PCR-based, molecular methods. BSL-2; Recertified through July 21, 2008.