Submitted to: Association for the Advancement of Industrial Crops Conference
Publication Type: Abstract Only
Publication Acceptance Date: 7/28/2014
Publication Date: N/A
Interpretive Summary: Natural rubber from guayule (Parthenium argentatum) may be more economically sustainable with improved yields through genetic engineering of rubber biosynthesis. However, it is difficult to transform the plants. A new protocol was developed for tissue culture of guayule with a 30% faster regeneration rate. This will accelerate the progress of guayule improvement. The knowledge gained may also be useful in establishing seedlings in greenhouse operations.
Technical Abstract: Natural rubber is one of the largest agricultural exports in the world, valued at over $33 billion in 2011 (faostat.fao.org). A 20-30% increase in demand for natural rubber is expected over the next 10 years, driven mainly by rapid economic growth in China & India. Development of additional sources of natural rubber represents a huge opportunity to create new biobased materials and industrial products. Natural rubber from plant sources, such as guayule (Parthenium argentatum) may be more economically sustainable with improved yields, through breeding or molecular engineering of rubber biosynthesis. Although the plant is drought-tolerant and readily cultivated in semi-arid regions, guayule can be recalcitrant with respect to regeneration and transformation for in vitro plant tissue culture, limiting the progress of metabolic engineering. Basal media including Murashige and Skoog (MS), Woody Plant Medium (WPM), and Driver and Kuniyuki (DKW) media were compared for use in guayule regeneration and propagation. Explants grown on MS basal medium showed large size calli with multiple shoots, but the calli produced on DKW medium were of higher quality, and longer true shoots were produced. Adventitious root formation was best in WPM basal medium. A comparison of macro and micro nutrient levels in MS, DKW, and WPM media revealed significant differences in the calcium levels. Under controlled conditions, guayule plants in vitro incorporated calcium into plant tissues in proportion to the amount available. Moreover, the addition of calcium nitrate tetrahydrate at moderate levels into MS medium significantly improved the emergence of single, elongated true shoots, suggesting a requirement for calcium in guayule tissue culture. The improved protocol generated shoots 30% faster than previously, advantageous for metabolic engineering of guayule. The knowledge gained may also be useful in establishing seedlings in greenhouse operations.