‘It's just a really super weird thing,’ says plant geneticist Andrew Leitch
If you want to understand the science of longevity and perseverance, you can't do much better than the Welwitschia plant.
Considered one of the toughest and longest-living plants, a Welwitschia can survive for thousands of years in the bone-dry deserts of southern Africa. And as long as it's alive, it never stops growing.
That's why scientists have studied the DNA of the Welwitschia, in the hopes of unlocking the secrets of its incredible ability to survive for millennia in extremely inhospitable conditions.
"It's just a really super weird thing," Andrew Leitch, a plant geneticist at Queen Mary University of London and one of the study's authors, told As It Happens guest host Katie Simpson.
"That's why you study weird and wonderful organisms — because they give you weird and wonderful insights that point you to directions you might never have thought of going."
Their findings were published last month in the journal Nature Communications.
'Two leaves that never die'
Welwitschia plants grow in the extremely arid desert along the border of southern Angola and northern Namibia. Scientists believe they get most of their water from morning mists that roll in from the Atlantic Ocean, condensing on their leaves and absorbing through their pores.
In Afrikaans, Welwitschia plants are called "tweeblaarkanniedood," which translates to "two leaves that cannot die."
Those two leaves grow continuously for thousands of years like some kind of infinite ticker tape, all the while cracking, splitting, sprawling and curling, giving the illusion of multiple leaves — or looking like "a giant green octopus," as Leitch puts it.
"They're coming out from under these giant woody lips like a leafy conveyor belt which never stops growing," he said.
He noted that in the 19th century, the director of the Kew Gardens in London said "it was out of the question, the most wonderful plant ever brought to the country and one of the ugliest."
The Welwitschia's leaves protect an area called the basal meristem, which Leitch says is the key to its longevity.
Most plant leaves grow from the tip outward. But the Welwitschia's two leaves grow continuously from the base, with the meristem supplying them with a constant stream of fresh cells.
"They protect that meristem with all sorts of genetic tricks. And those are the things that we were looking at in the genome," Leitch said.
The researchers say they've identified large numbers or copies of genes connected with efficient metabolism, cell growth and stress resilience.
But while the base keeps growing, the ends of the leaves eventually die, either drying up in the sun, or getting slowly nibbled away by various other desert lifeforms. Only damage to the base of the plant will threaten its livelihood.
"Animals do in fact, eat the leaves, but damage those meristems stems under the lips, and that's it," Leitch said. "So, you know, they're very vulnerable at some level, as well as being extremely robust."
Leitch says the Welwitschia's genetic advantages could someday be applied to other crops.
"We've identified in this plant some genes that are important … and it could be that we now have targets, new targets, that we might be able to look at in agriculture," he said.
"And so that's why you do these things. As well as, of course, the fundamental biological insight it gives you to study weird plants where pretty well everything about them is unusual."