Genetic improvement of guayule (Parthenium argentatum A. Gray): An alternative rubber crop

Among the more than 2000 plant species known to synthesize rubber, guayule, Hevea and Taraxacum kok-saghyz produce commercial grade rubber and latex. Guayule (Parthenium argentatum A. Gray), originates from the Southern Texas and Northern Mexico deserts, and is receiving wide attention as a natural rubber crop that could successfully grow in arid and semiarid regions. Continued improvement of guayule for higher biomass, rubber production and resistance to biotic and abiotic stresses, as well as maximizing agronomic practices are necessary to meet the increasing demand of the guayule rubber industry. Early domestication and commercialization efforts have all centered on using natural guayule stands and unimproved germplasm as a source of natural rubber. However, limited and sporadic breeding efforts have slowed down guayule's genetic gains compared to other crops. This chapter summarizes the most recent breeding progress, biotechnological advancements, and agronomic practices to increase guayule rubber and other industrial byproducts. This provides plant breeders an insight into the status of guayule improvement and possible directions to speed up the breeding progress.