Hevea brasiliensis
Hevea brasiliensis, the Pará rubber tree, sharinga tree, seringueira, or most commonly, rubber tree or rubber plant, is a flowering plant belonging to the spurge family, Euphorbiaceae, originally native to the Amazon basin, but is now pantropical in distribution due to introductions. It is the most economically important member of the genus Hevea because the milky latex extracted from the tree is the primary source of natural rubber.
For the common ornamental plant, see Ficus elastica.Environmental concerns[edit]
The toxicity of arsenic to insects, bacteria, and fungi has led to the heavy use of arsenic trioxide on rubber plantations, especially in Malaysia.[20]
The majority of the rubber trees in Southeast Asia are clones of varieties highly susceptible to the South American leaf blight—Pseudocercospora ulei. For these reasons, environmental historian Charles C. Mann, in his 2011 book, 1493: Uncovering the New World Columbus Created, predicted that the Southeast Asian rubber plantations will be ravaged by the blight in the not-too-distant future, thus creating a potential calamity for international industry.[21]
Secondary metabolites[edit]
Hevea brasiliensis produces cyanogenic glycosides (CGs) as a defense, concentrated in the seeds. (Although effective against other attackers, cyanogenic glycosides are not very effective against fungal pathogens. In rare cases, they are even detrimental. This is the case for the rubber tree, which actually suffers worse from Pseudocercospora ulei when it produces more cyanogenic glycosides. This may be because cyanide inhibits the production of other defensive metabolites. This results in significantly divergent subpopulations with selection for or against cyanogenic glycosides, depending on local likelihoods of fungal or non-fungal pest pressure.) The carbon and nitrogen in CGs are recycled for growth and latex production if needed, and the ease of doing so makes them an attractive nitrogen store - especially if the plant is light-deprived and storage in photosynthesis proteins would thus be unhelpful. The α-hydroxynitriles are likely contained in the cytoplasm. Linamarin is hydrolyzed by an accompanying linamarase, a β-glycosidase. Hevea brasiliensis linamarase does act upon linamarin because it is a monoglucoside, while it does not for linustatin because it is a diglucoside - in fact, the production of lovastatin inhibits linamarase cleavage of linamarin. This allows intra-plant, post-synthesis transport of linustatin without risking premature cleavage.[22]