Researchers Sequence Genome of Tropical Fruit Durian

An international team of researchers from Singapore, Hong Kong and Malaysia has sequenced the genome of durian (Durio zibethinus), a Southeast Asian tropical plant known for its hefty, spine-covered fruit and sulfury and onion-like odor.

Durian (Durio zibethinus). Image credit: Amon Heijne / CC BY-SA 3.0.

Durian is an edible tropical fruit endemic to Southeast Asia.

In the region, durian is known as the ‘king of fruits’ for its formidable spiny husk, overpowering flavor, and pungent odor, described as an onion-like, sulfury aroma with notes of sweet fruitiness and savory soup seasoning.

The three leading durian-producing countries are Thailand, Malaysia, and Indonesia, with more than 250,000 ha cultivated in 2008.

More than 200 different cultivars of durian exist, encompassing a range of fruit textures, flavors, and aromas.

Distinct regional demands for different cultivars reflect local idiosyncrasies in consumer tastes: pungent and bitter varieties are prized in Malaysia and Singapore, whereas sweeter cultivars with a mild odor are popular in Thailand.

Using state-of-the-art sequencing platforms, Duke-NUS Medical School researchers Bin Tean Teh and Patrick Tan and co-authors mapped the genome of a particular durian variety called Musang King, known for its exceptionally delicate texture and potent aroma and considered as the ‘king of kings’ in the local durian world.

Characterization of the durian (Durio zibethinus) genome: (a) circos plot of the multidimensional topography of the D. zibethinus genome (right), comprising 30 pseudomolecules that cover ~95% of the assembly; concentric circles, from outermost to innermost, show (1) gene density, (2) repeat element density, (3) GC content, and (4) syntenic regions with Theobroma cacao (left), the closest sequenced relative in the Malvaceae family that did not undergo a recent whole-genome duplication event; (b) distribution of repeat classes in the durian genome; (c) distribution of predicted genes among different high-level Gene Ontology (GO) biological process terms; (d) sharing of gene families by durian and three other Malvales plants, with Arabidopsis thaliana as an outgroup; the number in parentheses indicates durian-specific gene families among all 11 plants considered. Image credit: Teh et al, doi: 10.1038/ng.3972.

The team’s analysis revealed that the durian genome comprises approximately 46,000 genes — almost double that in humans.

Based on the newly generated genomic data, the authors also studied the evolution of durian and traced its relationship 65 million years back to the cacao plant Theobroma cacao.

They also focused on the million dollar question: ‘what causes the durian’s notorious smell?’

By comparing gene activity patterns from different parts of the durian plant, including leaves, roots, and ripening fruits, they identified a class of genes called methionine gamma lyases that regulate the production of volatile sulfur compounds (VSCs).

“Our analysis revealed that VSC production is turbocharged in durian fruits, which fits with many people’s opinions that durian smell has a ‘sulfury’ aspect,” Professor Tan said.

“In the wild, the ability of durians to produce high VSC levels and a pungent smell may be important in attracting animals to eat and disperse durian seeds to other regions,” the researchers said.

The research is published in the journal Nature Genetics.

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Bin Tean Teh et al. The draft genome of tropical fruit durian (Durio zibethinus). Nature Genetics, published online October 9, 2017; doi: 10.1038/ng.3972