Wounding and cold stress increase resin and rubber production of Parthenium argentatum cultivar G711

The world's supply of natural rubber is primarily extracted from tropical Hevea brasiliensis trees and is an essential component of many industrial goods. Guayule (Parthenium argentatum) is a very promising alternative source for natural rubber. Abiotic stresses (cold, drought) can increase rubber production in guayule. Here, we investigated the impact of wounding and cold on guayule plants under controlled (growth chamber) environments. Physical characteristics of the plant were measured as well as the levels of rubber, resin, and a wide range of phytohormones. There were significant changes in plant architecture, rubber and resin production, and in phytohormone levels when the plants were subjected to wounding and/or cold treatment. The highest rubber and resin production was found for cold + wounding stressed plants, where stem jasmonic acid concentration was at the lowest level. Results suggest that jasmonic acid and salicylic acid respond to abiotic stress antagonistically in guayule, and further, play a significant role in stress-induced rubber biosynthesis.