New Developments in Rubber Particle Biogenesis of Rubber-Producing Species

Natural rubber (NR) is a polymer critical to modern economies. However, the entire global supply is produced by one tropical tree species, Hevea brasiliensis (para rubber tree), derived from perhaps 20 plants collected over a century ago. This species is grown as clones making it even more genetically uniform. Efforts to diversify rubber production have led to ongoing development of alternative natural rubber-producing species. Taraxacum kok-saghyz (T. kok-saghyz) is an herbaceous plant of the Asteraceae family native to Kazakhstan. Similar to those in H. brasiliensis tree trunks, T. kok-saghyz roots produce rubber latex in multi-nucleate pipe-like laticifers. Fundamental knowledge of T. kok-saghyz anatomy, laticifer development and rubber biosynthesis is needed to accelerate its domestication. The origin of rubber particles may be particularly relevant to rubber yield. Microscopy methods were used to analyze rubber particle ontogeny in detail. Rubber particle ontogeny occurred before laticifers, apparently within the secretory pathway of the endoplasmic reticulum–Golgi vesicular complex. This is the first report of the origin of rubber particles in T. kok-saghyz seedlings. Unexpectedly, rubber particle development bifurcated in roots of mature plants, and laticifer plastids became a second rubber particle ontological site.