Aluminum (Al) toxicity is a profound limitation to crop production worldwide, reducing yields on up to 50% of potentially arable lands. Breeding for Al tolerance and agronomic practices aimed at ameliorating soil acidity have historically been productive avenues for improved crop production. However, it is widely recognized that additional tolerance enhancement will depend upon the identification of Al tolerance genes and mechanisms to facilitate improvement via biotechnology. We will identify and characterize Al tolerance genes and their associated mechanisms in maize, one of the most important crops grown on acid soils. Our study populations are derived from diverse sources; thus we will capture a wide range of Al tolerance levels and useful alleles. Central to the project are Al tolerant and sensitive NIL pairs representing the major QTLs we already have identified; these lines are a major resource for gene discovery. Our research objectives are: 1) Identify the physiological mechanisms for tolerance associated with specific QTLs; 2) Profile gene expression with selected NIL pairs to identify candidate Al tolerance genes underlying these QTLs; 3) Evaluate and confirm candidate tolerance genes via comparative genomics and genetic association analysis; 4) Deposit and curate the generated datasets (genetic linkage, phenotypes, microarray, nucleotide sequence) into publicly available databases including Gramene, the NSF Maize Genetic Diversity Project, and the MIAME compliant expression profiling repository for the NSF-funded Maize Oligonucleotide Project.
Broader Impacts of Proposed Research We will conduct fundamental research on an important worldwide agricultural problem. This problem is especially pronounced in South America and Africa, where maize is a staple crop and acid soils are prevalent. The proposed research should greatly expand our understanding of the molecular and physiological basis of Al tolerance, generating the molecular/genomic resources needed to enhance crop performance in acid soils. This information should be useful for both traditional and biotechnological crop improvement strategies. We will deposit the information from this project into public databases, which will be useful to a broad collection of basic and applied scientists; nucleotide polymorphism and phenotypic scoring data collected from distantly related maize cultivars should be of particular interest to molecular evolutionary biologists and breeders. Furthermore, we will facilitate the participation of under-represented groups in science by participating in the summer internship program that targets recruitment of minority undergraduates that has been established at Cornell University and The Boyce Thompson Institute through funding by NSF (the Plant Genome Research Outreach program). Additionally, we have established and will continue to run an undergraduate summer intern program with California State University at Fresno to recruit Hispanic undergraduate students into USDA-ARS labs.
