The focus of research in the Giovannoni laboratory is molecular and genetic analysis of fruit ripening and related signal transduction systems with emphasis on the relationship of fruit ripening to nutritional quality. We employ several experimental systems but the majority of our work involves the use of tomato. The broad objectives of the lab include deciphering the underlying molecular basis of components of ripening regulation conserved through evolution and how these regulatory networks coordinate ripening events including those related to quality and nutritional content.
The utility of plant-derived carotenoids, long know to serve as vitamin A precursors (beta-carotene), have become more recent targets of scientific and consumer interest due to documented antioxidant phytonutrient potential (e.g. lycopene). While much is known about the carotenoid synthesis pathway, little is known about how metabolic flux through this pathway is regulated and thus could be optimized for human benefit. A well-characterized tomato mutation termed "high-pigment" (hp) is a rare example of a genetic regulator of total carotenoid accumulation and has long been of interest to tomato breeders as a tool to elevate carotenoid and associated color and nutrient activities in fruit. We have recently isolated the gene responsible for the tomato hp mutation and the resulting gene sequence will be useful both as a molecular marker for tomato breeding and as a tool for enhancing carotenoid accumulation in transgenic fruit of tomato and additional crop species.
Substantial effort in the laboratory has also been directed toward isolation of several genes (rin; ripening-inhibitor, nor; non-ripening and Nr; Never-ripe) previously identified via mutation to be intimately involved in the primary regulation of tomato fruit ripening. Mutations at these loci result in fruit that are either partially or completely inhibited in their ability to ripen. The rin and nor loci have been cloned in our lab and confirmed via complementation in transgenic mutant plants. Both genes are members of distinct transcription factor families, neither of which have been previously associated with the ripening process. The importance of the RIN and NOR genes lies in the fact that they represent developmental control points influencing ripening, but presumably prior to induction of ethylene biosynthesis, and thus may represent developmental regulatory components common among diverse fruit species.
Finally, in collaboration with other groups at Cornell and BTI (Steve Tanksley, Greg Martin, Joyce VanEck), the University of Arizona (Rod Wing) and The Institute for Genomics Research (TIGR) we are involved in the coordinated development of an integrated set of experimental tools for use in tomato functional genomics. The resources developed are being used by our group to further expand our understanding of the molecular genetic events underlying fruit development and are being made available to the research community for analysis of diverse plant biological phenomena.
Important CRIS web sites
Tomato Expression Database (TED)
Cucurbit Genomics Database
SOL Genomics Network (SGN)