A SYSTEMS BASED APPROACH FOR THE IDENTIFICATION OF RUBBER BIOSYNTHETIC GENES IN THE HYPER-RUBBER-PRODUCING COMPOSITE SPECIES Parthenium argentatum AND Taraxacum kok-saghyz

¹ University of Nevada, Dept. of Biochemistry/MS200, Reno, NV, 89557, USA

² USDA-ARS, WRRC/CIU, 800 Buchanan St., Albany, CA, 94710, USA

Natural rubber is a strategically important plant commodity required in the manufacture of industrial and medical products. While the sole commercial source of natural rubber is Hevea brasiliensis, it is also produced by over 2,500 different plant species. A number of Composite species including lettuce, sunflower, Parthenium argentatum(Guayule), and Taraxacum kok-saghyz (Russian dandelion) also synthesize rubber. While the commercially important Composites, sunflower and lettuce, do not produce rubber of sufficient quality or quantity to be of commercial interest, Guayule, and Russian dandelion do. In fact, during World War II, when rubber was scarce, these two Composites were used as emergency rubber crops. Such experiences with rubber shortages justify the need for rubber producing crops alternatives to Hevea brasiliensis. Obvious targets for such alternatives include lettuce and sunflower, which are both widely cultivated and have significant genetic resources to make breeding or genetic engineering efforts to develop hyper-rubber-producing varieties possible. Although these to plant species are capable of producing rubber, because of low levels of rubber production, both make poor systems for rubber biosynthetic genes/proteins identification. To circumvent this problem we have employed Guayule and Russian dandelion as systems to functionally identify rubber biosynthetic genes/proteins. Our approach is to use proteomics in conjunction with EST sequencing to identify candidate rubber biosynthetic genes. These genes will then be functionally analyzed for their role in rubber biosynthesis using a reverse genetic approach with transgenic Russian dandelion. Such genes can then be used to genetically engineer/breed for hyper rubber producing lettuce or sunflower.