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Unlocking the Secrets of the Corpse Flower
The titan arum, commonly referred to as the corpse flower due to its notorious scent resembling decaying flesh, captivates both scientists and visitors alike during its rare blooming events. While its distinctive aroma attracts crowds across greenhouses worldwide, researchers are equally fascinated by the plant’s ability to generate heat just before it blooms, a phenomenon known as thermogenesis. This unusual trait presents a complex area of study as it is not commonly observed in the plant kingdom.
A recent research initiative led by Dartmouth College has delved into the genetic and biological frameworks that govern the corpse flower’s production of heat and its characteristic odor during blooming. The findings, published on November 4 in PNAS Nexus, detail the work of G. Eric Schaller, a professor of biological sciences, and his team as they explore the underlying mechanisms of this plant’s remarkable characteristics. Notably, the researchers identified putrescine, a compound contributing to the corpse flower’s signature scent.
The research centered around Morphy, a 21-year-old corpse flower housed in Dartmouth’s Life Sciences Greenhouse. Utilizing multiple bloom events, the team gathered tissue samples for in-depth genetic and chemical analyses.
The titan arum is not a singular flower but rather a compilation of numerous small flowers encased within a towering central structure known as the spadix, which can reach heights of up to 12 feet. The flowering cycle of this plant is infrequent, typically occurring every five to seven years, and blooms can happen overnight. As Schaller notes, “The blooms are rare and also short-lived, so we only get a small window to study these phenomena.”
As the spathe, a petal-like covering at the base of the spadix, unfolds, it forms a cup around the stalk, showcasing a striking deep red interior. This is soon followed by an increase in temperature, with the spadix heating up to 20 degrees Fahrenheit above the surrounding air. The heat, along with a release of sulfur-based compounds, serves to attract pollinators like flies and carrion beetles essential for the plant’s propagation.
During Morphy’s 2016 bloom, researchers collected nine tissue samples across three nights, starting at the peak of the spadix’s temperature. Samples were taken from various areas of the spathe and the spadix itself, along with additional leaves for comparison.
Alveena Zulfiqar, a visiting research scholar in Schaller’s lab, successfully extracted high-quality RNA from the samples, which allowed the team to analyze gene expression linked to the plant’s thermal and olfactory signaling. “This helps us see what genes are being expressed and to see which ones are specifically active when the appendix heats up and sends out odor,” explains Schaller, who is also known for his short horror fiction, accentuating the intriguing intersection of science and creativity embodied by the corpse flower.
While thermogenesis is a common occurrence in animals, it is a rarity among plants. In animals, uncoupling proteins play a crucial role in converting stored chemical energy into heat. Schaller’s investigation revealed that plant equivalents, termed alternative oxidases, showed heightened expression in the tissues when the plant began to flower, particularly in the appendix. Genes related to sulfur transport and metabolism were also notably active during this phase.
To further unveil the operational mechanisms of these genes, the team analyzed tissues from a subsequent bloom. Collaborating with researchers at the University of Missouri, they employed mass spectrometry to quantify different amino acids present in the samples. Consistent with their RNA analysis, the researchers found elevated concentrations of methionine, a sulfur-containing amino acid known to produce strong odors when heated. Interestingly, levels of methionine decreased rapidly in later samples.
A surprising discovery, according to Schaller, was the identification of elevated levels of putrescine, a compound associated with decomposing organic matter, found in samples from the spathe. This study marks a significant stride in understanding the corpse flower’s unique odor at a molecular level, the mechanisms behind its temperature regulation, and the roles of various parts of the flower cluster in generating the attractive scent crucial for pollinator interaction.
Schaller remains committed to further exploration of Morphy’s mysteries, now focusing on potential triggers for flowering and the possibility that neighboring specimens might synchronize their blooms to amplify the odor and enhance pollinator attraction.
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