Submitted to: Phytochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/24/2006
Publication Date: 10/20/2006
Citation: Bushman, B.S., Scholte, A.A., Cornish, K., Scott, D.J., Brichta, J.L., Vederas, J.C., Ochoa, O., Michelmore, R.W., Shintani, D.K., Knapp, S.J. 2006. Identification and comparison of natural rubber from two lactuca species. Phytochemistry 67(2006): 2590-2596
Interpretive Summary: The objective of our CRIS project is to develop commercially-viable natural rubber-producing crops suitable for cultivation in the temperate climate of the United States. Success will improve supply security in the Unites States, and provide a solution for people with Type I latex allergy while enhancing rural development with new industrial rubber-producing crops. Over 2500 plant species produce natural rubber; commercialization of guayule (Parthenium argentatum) is proceeding successfully, but is limited primarily to the southwestern United States. Evaluation of alternate candidate species with broader crop potential will help identify crops for rubber production in other climates. This study evalutes two species of lettuce, a rubber-producing crop with broadly developed agronomic practices.
Technical Abstract: Renewed interest in the identification of alternative sources of natural rubber to Hevea brasiliensis has focused on the Compositae family. In our search for Compositae models for rubber synthesis, we extracted latex from stems of two lettuce species: Lactuca serriola, prickly lettuce, and Lactuca sativa cv. Salinas, crisphead lettuce. Both species contained cis 1,4-polyisoprene rubber in the dichloromethane- soluble portions of their latex, and sesquiterpene lactones in their acetone-soluble portions. The rubber from both species and their progeny had molecular weights in excess of 1,000,000 g/mol, and polydispersity values of 1.1. Rubber transferase activity was detected across a range of farnesyl diphosphate initiator concentrations, with decreased activity as initiator concentrations exceeded putative saturation. These results add lettuce to the short list of plant species that produce high molecular weight rubber in their latex. Due to the genomic and agronomic resources available in lettuce species, they provide the opportunity for further dissection of natural rubber biosynthesis in plants.