Project Number: 1907-21000-025-00
Project Type: Appropriated

Start Date: Jun 01, 2006
End Date: May 31, 2011

Objective:
The primary objective of this research project is to identify genes and define molecular mechanisms that regulate nutritional content, quality and availability of plant-based foods with a primary emphasis on carotenoids. The value of such research will be in expanding the knowledge base of molecular biology related to crop nutrient quality and more specifically, to understanding of primary and secondary biochemical pathways and associated genetic regulatory systems that influence nutritional characteristics of plant-derived foods. Discoveries resulting from activities pursued through this project will lead to molecular tools for testing biochemical and molecular regulatory hypotheses and eventually for manipulating crop nutrient profiles and\or content. Implementation of said discoveries will be through both creation of genetically modified crops plants and indirect genetic manipulation via DNA markers associated with target nutrient traits. Resulting genetically modified plants will further be useful in testing not only nutrient levels but also availability to humans through diet within the context of a given crop tissue or derived food. Specific broad objectives of this project include: Objective 1: Define genetic regulatory mechanisms that control endogenously regulated and environmentally influenced synthesis and accumulation of carotenoids in plant-based foods. Objective 2: Develop and characterize genetic and biochemical plant attributes contributing to regulation of accumulation of carotenoids with exploratory efforts toward additional plant-derived nutrients.

Approach:
Efforts will focus on the use of tomato and cauliflower for identification and characterization of nutrient-related genes with primary emphasis on carotenoids. We propose expansion of the tomato model to include analysis of genome-wide expression patterns during fruit development and ripening. We will perform comparative expression profiling of pre-ripening and ripening fruit from normal, ancestral and mutant varieties, combined with HPLC analysis of carotenoid accumulation to identify candidate transcription factors impacting fruit carotenoid accumulation. Additional insights into transcriptional control of carotenoid accumulation will be developed through analysis of protein accumulation profiles in addition to (and in some cases in support of) transcription data. A major goal of this project is to identify novel genes involved in or regulating a specific metabolite pathway using correlation analysis between genotype, metabolite and gene expression data. We will develop both biology-driven and statistics-driven integration tools that will be presented to the research community and broader public via the world wide web. The secondary model for our activities will be cauliflower as both a source of unique genetic variation related to carotenoids and a member of the Brassicaceae which includes many important vegetable species. Previously, we have demonstrated that expression of the Or genomic DNA allele in transgenic cauliflower induced carotenoid accumulation. To begin to shed light on the nature of the Or mutation and endogenous OR protein function, we propose to generate both "knockout" and over-expression lines in cauliflower. We will employ a range of proteomics approaches including 2-hybrid, gel filtration and mass spectrometry to identify proteins that interact with Or. Finally, as a relatively minor activity and in an effort to identify future areas of promise, we will begin to improve our understanding of Se metabolism in plants for enhancing the biosynthesis of functional forms of organoselenium compounds. We will employ molecular and genomics approaches to identify, isolate and characterize important genes controlling Se metabolism.