1a.Objectives (from AD-416)
The objective of this cooperative research project is to identify and functionally test genes that are important in the regulation of plant compounds with known or potential human health benefits. In doing so, we will identify candidates for manipulation through traditional breeding or transgenic strategies for enhancement of phytonutrients in plant-based foods and we will additionally develop basic knowledge regarding the genetic mechanisms underlying the synthesis and accumulation of target compounds. Specific compounds of interest under this project will be carotenoids, flavonoids, ascorbate, and folic acid.
1b.Approach (from AD-416)
The general approach of this cooperative research project will entail continued utilization of emerging genomics technologies to identify genes related to phytonutrient accumulation in tomato with a secondary effort on melon. We will continue to screen and expand set of tomato and melon germplasm developed as part of the prior project which varied in target nutrient and phytonutrient levels for genes whose expression is coordinated with changes in metabolite targets of interest. Considerable germplasm appropriate for this study is available and already in hand in the ARS lab and from collaborators in ongoing projects. Genes will continue to be screened initially via transient viral induced gene silencing (VIGS) which is an expertise of our collaborator. Genes coming through the VIGS screens with an impact on phytonutrient levels will be used in development of a smaller number of stable transformants for comprehensive analysis. The ARS lab is proficient in tomato gene expression profiling using microarrays and more recently RNAseq technologies and in the creation and analysis of stable transformed tomato lines. Candidate melon genes (or their homologs) will be initially analyzed in tomato. As stated, the BTI cooperator’s lab is proficient in creation and high throughput transient expression of DNA constructs for testing function of candidate genes in tomato. The complementary skills and mutual interests of the ARS and BTI groups make this an ideal collaboration.
This project is focused on characterization of fruit and vegetable nutritional metabolites and the genes that control their synthesis and accumulation. Identification of biosynthesis and regulatory genes that impact fruit and vegetable nutrients and the biological process that are associated with them (e.g. fruit ripening) will provide new targets for selection and breeding toward a more nutrient diverse and nutrient dense food supply. The seed companies that generate them, the farmers who grow them, the processors who use them and the consumers who eat them will all benefit from nutrient enhanced crops. This has been the first year of the project and it will focus initially on tomato as a model for fruit nutritional biology and expand to other species as the project unfolds. Initial project activities have involved generation of plant material for analysis including tomato fruit from multiple genotypes and maturity stages. Replica tissues will be collected over several seasons to distinguish genetic from environmental variation. Harvested and frozen tissues will then be extracted for RNA (to measure gene expression) and target nutritional metabolites (pro-vitamin A and additional carotneoids, flavonoids, ascorbic acid /vitamin C and folic acid/vitamin B9). The initial year harvests and metabolite analyses are complete. This project is in all respects on schedule and on budget. Two separate project meetings and several informal meetings were held over the course of the year to insure project activities remained on track, problems were addressed and all project participants were current on activities occurring in cooperating laboratories. Project participants including project leaders and key technicians, postdocs and graduate students involved in the project met quarterly in person or via conference calls (to include external collaborators). Regular meetings between the project PIs, phone conversations and email are used on a frequent basis as needed to address questions, technical problems, or to plan next steps when milestones are reached. Meetings with the primary collaborators are easily accomplished as they are located on the Cornell campus.