The corpse flower lives up to its nickname. The giant tropical plant is native to the Sumatran rainforests of Indonesia and can live for decades and grow more than 3 meters tall, but is best known for the deadly odor it emits when flowering. And while Titan Arum’s rotten flesh smell is unmistakable to anyone standing near it, experts have long been at a loss as to how it chemically generates the odor. But the molecular mystery has now reportedly been solved thanks to new research from a team at Dartmouth University. According to their study published on November 4 in PNAS nexusthe stench of the corpse flower mainly comes from an organic compound, combined with a biological process that usually only occurs in animals.
A titanium arum does not bloom annually, but instead undergoes a short bloom cycle once every five to seven years. Within just a few days, a dark red, ruffled layer of petals opens at the base of the plant’s large central stem. The corpse flower is also not technically single, but instead contains multiple smaller flowers in this stem, known as a spadix. Once exposed to potential pollinators, the cob of the Titan Arum begins to heat up as much as 20 degrees Fahrenheit higher than the ambient temperature surrounding it, in a process called thermogenesis. Only then does the corpse flower begin to release its sulphurous chemicals intended to attract flies and other insects.
Thermogenesis is common in animals thanks to uncoupling proteins, which block the storage of chemical energy to redirect it as heat. But thermogenesis is extremely rare in plants, and botanists didn’t know what caused it in corpse flowers. Dartmouth’s own 21-year-old giant arum, nicknamed Morphy, last bloomed in 2016 and 2022. Both times, researchers led by biological sciences professor G. Eric Schaller collected tissue and leaf samples that they then used for RNA sequencing.
[Related: Corpse flowers across the country are swapping pollen to stay stinky.]
“This helps us see which genes are expressed and which ones are specifically active when the appendix warms up and releases odor,” he explained in a study. university profile on November 8.
Schaller and his collaborators then identified what triggers corpse flower thermogenesis, as well as the specific chemical culprits behind its scent. RNA analysis discovered the presence of enzymes called alternative oxidases that increased in number during Morphy flowering, as well as genes required in the metabolism and transport of sulfur.
With help from researchers at the University of Missouri, the team then used mass spectrometry to measure the amino acid content of the corpse flower. In particular, researchers noted high levels of methionine, which underlies compounds responsible for foul-smelling odors. Although this was previously predicted by Schaller’s team, they also discovered the active enzymes that make putrescine – the compound found in the odors emitted by rotting animals.
All told, the discoveries may not do much to alleviate the corpse flower’s awful smell, but experts can at least now pinpoint how titan arum generates such impressively bad aromas. In the future, Schaller hopes to learn what initiates a corpse flower’s bloom cycle, and whether multiple plants synchronize their schedules to increase the chance of pollination.