Genetics of the Longest Living Plant Revealed
By Alexander Gu
The welwitschia, a plant that lives in the harsh desert between southern Angola and northern Namibia, the Namib desert, can live for thousands of years. The Afrikaans call it ‘tweeblaarkanniedood’, which means “two leaves that cannot die.” A name that perfectly describes the plant. It has two leaves and can live for millenia.
The welwitschia never stops growing. Some of the largest are thought to be around 3,000 years old. They have been never endingly growing since the Iron Age. The welwitschia’s leaves shred and curl with age, giving it the shape of an octopus. One director of Kew Gardens in London from the 19th-century stated that even though it is the most wonderful plant ever brought to England, it is definitely the ugliest.
The genome of the plant reflects the harsh and nutrient-poor environment it lives in. “Approximately 86 million years ago, after a mistake in cell division, the entire Welwitschia genome doubled during a time of increased aridity and prolonged drought in the region — and possibly the formation of the Namib Desert itself,” said Tao Wan, a botanist at the Fairy Lake Botanical Garden in Shenzhen, China, and lead author of the study. He also stated that extreme stress is thought to be a cause of such genome duplication. A large amount of welwitschias’s genome is self-replicating sequences called retrotransposons. This “junk” also needs to be replicated and repaired. A burst of retrotransposon activity was detected 1-2 million years ago, likely because of rising temperature stress. This caused the DNA to shrink in size and become much more efficient.