Asian Scientist (Jul. 26, 2013) – An international team of researchers has analyzed the oil palm genome, revealing insights that may help improve the use of this oil plant species.
The two species of oil palm (African and South American) together account for 45 percent of the edible vegetable oil supply worldwide. Palm oil also shows great potential as a biofuel as it yields about 9 times the energy required to produce it.
Now, researchers have decoded the oil palm genome and released their findings in two papers published in Nature this week. One of the papers reported the mapping of both the African and South American oil palm species while the second study focused on the identification of a single gene responsible for the three different fruit forms of the modern palm which have different oil yields.
What the oil palm genomes reveal
One of the newly published genome maps is the 1.8 gigabase sequence of the E. guineensis African oil palm. It comprises nearly 35,000 genes, including the full set of oil biosynthesis genes and other transcriptional regulators highly expressed in the oil-rich palm fruit.
The researchers also created a draft sequence of the South American oil palm E. oleifera. Both palm species are in the Arecaceae family of flowering plants, which fossil evidence dates to the Cretaceous period, an estimated 140 to 200 million years ago.
According to the researchers, the complete genome sequence of oil palm will be a rich resource for oil palm breeders, geneticists and evolutionary biologists alike.
A gene responsible for oil yield
In the second paper, the team identified a single gene, called Shell, responsible for the oil palm’s three known shell forms: dura (thick); pisifera (shell-less); and tenera (thin), a hybrid of dura and pisifera palms.
Tenera (thin-shelled) palms contain one mutant and one normal version, or allele, of Shell, an optimum combination that results in 30% more oil per land area than dura (thick-shelled) palms.
This is the single most important characteristic of oil palm from an economic perspective, which is why the tenera variety forms the basis for commercial oil production.
“The discovery that regulation of the Shell gene will enable breeders to boost palm oil yields by nearly one-third is excellent news for the rainforest and its champions worldwide,” says Dr. Choo Yuen May, the Director General of the Malaysian Palm Oil Board (MPOB).
How the discovery will affect plantation management and land use
Seed producers can now use the genetic marker for the Shell gene to distinguish the three fruit forms in the nursery long before they are field-planted. Currently, it can take six years to identify whether an oil palm plantlet is a high-yielding palm.
Even with selective breeding, 10 to 15 percent of plants are the low-yielding dura form due to uncontrollable wind and insect pollination, particularly in plantations without stringent quality control measures.
“The discovery of Shell indicates a clear path toward more intensive use of already planted lands,” said Dr Robert A. Martienssen, a member of the research team.
“Accurate genotyping for enhanced oil yields will optimize and help stabilize the acreage devoted to oil palm plantations, providing an opportunity for the conservation of rainforest reserves.”
The Malaysian government halted the conversion of new forest land for agriculture, including palm oil, in the 1990s. According to the MPOB, the government has committed to preserve 50 percent of Malaysia’s total land area as forest. To meet increased demand for palm oil, the government had converted colonial rubber and cocoa plantations to oil palm plantations.
The articles can be found at:
Singh et al. (2013) Oil Palm Genome Sequence Reveals Divergence Of Interfertile Species in Old And New Worlds.
Singh et al. (2013) The Oil Palm SHELL Gene Controls Oil Yield And Encodes A Homologue Of SEEDSTICK.
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Sources: Nature and Cold Spring Harbor Laboratory. Photo: DrLianPinKoh/Flickr.
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