ABSTRACT

PI: Andrew Hanson (University of Florida-Gainesville)

Co-PIs: Christopher Henry (University of Chicago), Donald McCarty and Jesse Gregory (University of Florida-Gainesville)

Key Collaborators: Alisdair Fernie (Max Planck Institute, Golm, Germany) and Svetlana Gerdes (Argonne National Laboratory)

Plants need B vitamins just as much as humans do but, unlike humans, plants make their own vitamins. However, it has been hypothesized that plants can fail to make all the B vitamins they need when exposed to heat, drought, or other climatic stresses, and that the resulting vitamin deficiencies cause metabolic defects leading to yield and vigor losses. Using maize, this project will exploit cutting-edge genetic, genomic, and metabolic computer modeling approaches to test this hypothesis, i.e. to determine the extent to which climatic stress effects on metabolism are due to B vitamin deficiency. Potential outcomes include the provision of a new paradigm for understanding stress metabolism and breeding for adaptation to climate stress, and the identification of specific genes to improve stress adaptation. With regard to outreach and training, the project will provide for research training activities that will put genome-scale metabolic modeling in researchers' hands. In addition to the training of postdoctoral associates and students, the project will hold a yearly workshop in metabolic modeling and comparative genomics to train faculty, postdoctorals, and students with an emphasis on those from Minority-serving Institutions.

B Vitamins form a network. Past studies imply that this network is severely impacted by climatic stresses and that the resulting vitamin deficiencies lead to plant underperformance. However the surprising idea that stresses cause B vitamin deficiencies has never been rigorously tested. Nor have the metabolic consequences of B vitamin depletion in plants been systematically defined. This project will do both using a metabolic systems approach with maize as a model. It will also fill crucial gaps in the B vitamin network by identifying 'missing' transporters and enzymes. Project objectives are to create a panel of vitamin B-deficient maize lines and acquire transcriptome and metabolome data; build metabolic models that - for the first time in plants - will include all B vitamins/cofactors as working parts and use them to predict how vitamin deficiency affects leaf metabolism and gene expression; predict stress-induced vitamin deficiency by comparing climate-stress and vitamin-deficiency transcriptomes and metabolomes, and validate predictions by supplying vitamins; and, identify candidate transporter and enzyme genes from transcriptome data and modeling, validate them biochemically and genetically, and upgrade the model by adding them. This research will inform perspectives on how B vitamin deficiency impacts plant gene expression and metabolism and in so doing, provide new insight into the manipulation of stress metabolism and breeding for metabolic adaptation to climate stress. All genome-scale datasets will be publicly available at PlantSEED (http://plantseed.theseed.org/) and GEO (www.ncbi.nlm.nih.gov/geo/). The project's annotation, metabolic reconstruction, and modeling capabilities will also be publicly available in PlantSEED and will be leveraged to support Gramene, the iPlant Collaborative, and the AraCyc, MaizeCyc, and PlantCyc databases. Vitamin-deficient maize lines will be a unique resource to study B vitamins and their exchange with the microbiome, and will be made publicly available via the Maize Genetics Cooperation Stock Center.

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