There are strategic as well as economic incentives to develop a renewable, United States-based supply of natural rubber. Currently, nearly all commercial natural rubber comes from a single species, the Brazilian rubber tree (Heveabrasiliensis) and the US is almost completely dependent on imports from distant countries. Global natural rubber production will be best served in the future by multiple natural rubber crops. However, for most rubber crops, the ability to produce rubber that is economically competitive with rubber from Hevea brasiliensis is essential, because the largest increasing demand for rubber is to make tires as China and India industrialize.
Leaves of sunflower (Helianthus annuus) produce rubber and researchers have postulated there is genetic potential for increasing the rubber content of cultivated H. annuus. Sunflower is a good candidate as a potential rubber source because this plant species already makes rubber which means it can compartmentalize this secondary product, it is adapted for agronomic production, it produces high biomass per acre, and sunflower agronomy is well understood and would need only minor adjustment as a rubber crop.
H. annuus currently produces little rubber of low molecular weight and also is notoriously recalcitrant to genetic transformation. In this paper, we describe progress in the development of tissue culture, transformation and regeneration of H. annuus, and genetic engineering of sunflower for increased rubber quality and production.