LATEX AGGLOMERATION AND COAGULATION IN LATICIFERS OF LIVE TARAXACUM KOK-SAGHYZ (RUBBER DANDELION) ROOTS

ABSTRACT The commercialization of Taraxacum kok-saghyz (rubber dandelion) as an alternative rubber crop requires fundamental knowledge of latex, an aqueous suspension of rubber particles, and rubber yield and quality. Rubber particles are formed in the root laticifers from Golgi bodies via the vesicular trafficking system in the cytosol and are then translocated into the vacuoles for storage. However, when freshly harvested roots are processed to extract the latex, much of the latex has already coagulated into solid rubber, reducing the commercial viability of latex extraction from this species. The process of in vivo loss of the latex fraction was investigated histologically, by transmission electron microscopy, in roots of plants grown in soil or hydroponically. In both root types, some rubber particles agglomerated in the cytosol as a precursor to coagulation. Other rubber particles agglomerated and then coagulated after rubber particles were translocated into vacuoles, and also after the cell internal cytoplasmic structure degraded. Uniquely large rubber particles were formed in the vacuoles of hydroponically grown plants by particle coalescence, but were not found in soil-grown roots. Eventually, some root laticifers of both root types filled with solid rubber. The instability of the aqueous latex phase postontogeny through rubber particle agglomeration, coalescence, and coagulation suggests that commercial processes likely would involve root drying to convert residual latex into solid rubber followed by aqueous- or solvent-based extraction.