1a.Objectives (from AD-416):
To identify and characterize novel endogenous sources of resistance to ear rot and aflatoxin accumulation in corn.
1b.Approach (from AD-416):
The focus of this research will be on a subset of the proteins that have been
identified in proteomic screening conducted at the USDA/ARS/SRRC lab, as putatively involved in aflatoxin accumulation and/or ear rot resistance. Identified proteins will be further characterized and the corresponding genes will be isolated and cloned. Proteins will be expressed in a suitable in vitro system and their possible physiological functions will be investigated. Knowledge of A. flavus functional genomics techniques will be used to identify/test proteins for target-specific interruption of aflatoxin biosynthesis. The information obtained through the above studies will be used to explore the potential of the identified genes to serve as markers in marker-assisted breeding programs.
An interactome is an invaluable tool to predict protein-protein interactions in maize and to identify maize proteins and protein networks involved in resistance to biotic and abiotic stresses including the regulation of plant responses to plant pathogens. The interactome is also useful to annotate unknown proteins identified in maize through their predicted interaction with other annotated proteins. In fact, the predicted interactome will ultimately have different layers of confirmation of gene expression data and annotation through mining existing databases such as Go-Term and Interpro. Publically available maize gene expression data from microarray studies was mined. A time series of gene expression data in response to biotic and abiotic stresses was developed. This data will be used to identify important maize transcription factors (special genes that produce proteins that regulate gene expression) involved in the regulation of the response of maize to these stresses. The data will also be used to build a partial transcriptome (the full complement of unique sequenced messenger ribonucleic acid molecules that an individual produces) of maize. This will validate the interactome and help identify and eliminate false predicted interactions. A field study is in progress. In this study several maize lines are being challenged with Aspergillus (A.) flavus. The objective is to conduct a time-course study of the interaction between maize and A. flavus over a period of days. Next-generation sequencing will be used to capture gene expression profiles in maize and A. flavus during a narrow window of the early interaction between the two organisms. The goal is to uncover gene networks in maize and in A. flavus involved in this interaction. In parallel, Arabidopsis thaliana plants are being challenged with A. flavus. Gene expression profiles characterizing this interaction will also be determined and will be compared to the gene expression profiles characteristic of the maize/A. flavus interaction. This will help elucidate interactions that are specific to the maize/A. flavus system and will also allow for increasing the confidence in our predicted maize interactome.