Project Number: 5325-41000-040-00
Project Type: Appropriated

Start Date: Sep 01, 2002
End Date: May 27, 2004

Objective:
In order to create and develop new rubber-producing crops suitable for the American farm, we will generate high-yielding guayule lines and increase rubber yield and quality in sunflower through metabolic engineering. We will also determine the function of the different subunits of the rubber transferase complex using microbial systems and tobacco. The tobacco research may lead to rubber-producing tobacco lines as an additional rubber-producing crop. The microbial research may lead to bioreactor production of high value, novel, functionalized rubber polymers. Domestic rubber commercialization efforts will be supported by refinement of post-harvest management practices for guayule and sunflower and by fundamental and applied research into new bioproducts, novel properties and new uses, and biomass utilization for bioproducts and biofuels. Specifically we will conduct research on natural polymers, blends, and products with enhanced performance properties for commercial applications in the defense, aerospace and medical industries.

Approach:
We will purify and sequence subunits of the rubber transferase complex in Parthenium argentatum (guayule) and Hevea brasiliensis, biochemically demonstrated to be involved in enzyme activity, and clone the corresponding genes. We will transform P. argentatum, sunflower, tobacco and microbial species with the rubber transferase genes and evaluate the quantity and quality of the rubber produced, and metabolically engineer the underlying substrate production pathway as needed to optimize yield and quality. We will evaluate P. argentatum lines, transformed with genes for substrate synthesis, grown in the greenhouse and the field, for rubber yield and quality. We will determine endogenous biochemical factors regulating rubber molecular weight (a prime determinant of quality) in vivo for subsequent cloning of enzymes and genes and metabolically engineer P. argentatum to produce higher molecular weight rubber than currently available, and evaluate for predicted improvement of performance quality. We will identify genetic, environmental and management factors affecting post-harvest yield and quality of hypoallergenic latex from P. argentatum. We will determine structural and chemical parameters of enzyme/substrate interactions and design and synthesize substrate analogs to generate functionalized rubber polymers containing modified termini and modified methylene side groups, and evaluate chemical properties. We will characterize the unusual cold-temperature properties observed in P. argentatum rubber and latex materials and develop elastomeric materials malleable at colder temperatures than possible with currently available materials. We will characterize the bagasse after latex and rubber extraction and determine its potential in a wide variety of bioproduct and feedstock uses. Formerly 5325-41000-019-00D (8/02). BSL-?; IBC approval pending. 2 FY03 Program Increases. Add 1 SY.