Natural rubber is essential to a broad range of industries and a significant US import ($3.3 billion in 2010, IRSG), with tires (automotive, agricultural, and aviation) driving much of the demand. All tire manufacturers are dependent on either imported natural rubber from the Brazilian rubber tree [Hevea brasiliensis (Willd. ex A. Juss.) Müll. Arg.] or petroleum-based synthetic polymers as feedstocks. However, neither material is sustainable with respect to future demands. In order to address this issue, we are investigating guayule (Parthenium argentatum A. Gray), a perennial hardwood shrub native to the North American Chihuahuan desert, as a sustainable, US domestic alternative source of natural rubber.
Guayule produces significant quantities of natural rubber with moderate agronomic inputs. It has been studied as a source of domestic rubber by the public and private sectors, especially during times of short supply or high prices, and intermittently cultivated for over 70 years. However, it is currently still an emerging crop, and the development of guayule as a viable commercial source of natural rubber requires better yielding, agronomically robust varieties. In partnership with researchers at the USDA-ARS Arid Land Agricultural Research Center in Maricopa, Arizona, USDA-ARS Western Regional Research Center in Albany, California, and Cooper Rubber & Tire Company, our lab is developing genotyping tools for guayule and investigating the genetic diversity of current guayule breeding germplasm.
As a first step, we are conducting a single-nucleotide polymorphism (SNP) marker survey of approximately 100 guayule cultivars and germplasm lines of variable ploidy levels that constitute the US guayule germplasm collection. We will use this information to quantify the genetic diversity present in the germplasm collection and inform selection of cultivars and germplasm lines for future breeding efforts. Next, using the SNP data from the genome resequencing part of the project, we will next develop a custom SNP genotyping array or equivalent protocol to facilitate the deployment of SNP markers in guayule breeding programs. This work will provide unprecedented insight into the patterns and structure of nucleotide diversity in the guayule germplasm pool and lay the foundation for marker-trait associations.
Funding: USDA-NIFA/DOE BRDI 2012-10006.