The genetic diversity of Heveabrasiliensis can at last be known and preserved. H.brasiliensis is a native of the Amazon forest and the world’s only plant cultivated for the commercial production of natural rubber.
Its genetic diversity has been described by a group of Brazilian researchers affiliated with several different universities and research institutions in collaboration with colleagues at France’s Agricultural Research Center for International Cooperation & Development (CIRAD).
They analysed1,117 exemplars of Heveaspp plants available in South American public germplasm banks (genetic heritage). They also assembled a core collection of germplasm from almost 100 rubber trees representing all the genetic diversity identified in the study, which resulted from a project supported by FAPESP, was published in the journal PLoS One.
The accessions were genotyped with microsatellite molecular markers, also called simple sequence repeats (short segments of DNA that indicate the most recent evolutionary variations in an individual organism). These exemplars had been conserved in Brazil and French Guiana by collecting expeditions conducted during the past 35 years in the area of Madre de Dios, Peru, and the Brazilian states Acre, Rondônia, Mato Grosso, Pará and Amazonas.
Genetic analysis of the accessions showed that rubber tree populations can belong to two distinct groups based on genetic distance: a group from Mato Grosso and another group from Acre, Rondônia, Amazonas and Pará in Brazil, and Madre de Dios in Peru.
The study showed, for example, that cultivated rubber trees from Asia, where plantations were not successfully developed until the 1920s, are similar to those from Mato Grosso.
One reason for this, according to the researchers, is that the first rubber trees grown in Southeast Asia originated from more than 70,000 seeds smuggled out of an area near the Tapajós River, Pará, Brazil, by British adventurer and imperialist Henry Wickham in 1876.
He took the seeds to Kew Gardens in London, where a couple of thousand eventually germinated. The few seedlings obtained after germination were sent to Malaysia, currently the world’s leading producer of natural rubber, and were the origin of all the rubber plantations in Southeast Asia, according to an article.
Attempts to create and conserve rubber tree germplasm banks have been going on for the last 40 years. Scientists fear total loss of the Hevea germplasm due to the South American leaf blight. This is caused by Microcyclusulei, a fungus that infects young leaves, stems and fruits of H. brasiliensis, resulting in defoliation and eventual tree death.
Leaf blight had already exterminated a plantation of rubber trees in Fordlandia whichwas the largest plantation maintained by a company in the Amazon.