Saturday, October 9, 2010
Longest genome ever discovered - The Paris japonica sets world record
LONDON, UK -- Researchers at London's Kew Gardens have discovered that Paris japonica, a striking rare native plant of Japan, has a genetic code 50 times longer than that of a human being
- setting the new world record for the Longest genome ever discovered.
Photo:The Paris Japonica, a Japanese flower, has The World's Longest genome ever discovered. Photo: Karl Kristensen, Demark / Kew Botanical Gardens (enlarge photo)
The length of that code easily beats its nearest competitor, a long-bodied muck dweller known as the marbled lungfish.
"We were astounded really," said Ilia Leitch, of Kew's Jodrell Laboratory.
A genome is the full complement of an organism's DNA, complex molecules that direct the formation and function of all living organisms.
Among animals, some amphibians have enormous genomes, but the largest recorded so far is that of the marbled lungfish (Protopterus aethiopicus) with 132.83 pg(3) .
Among plants, the record holder for 34 years was a species of fritillary (Fritillaria assyriaca). However earlier this year a Dutch group knocked the fritillary off the top spot when they found that a natural hybrid of trillium (Trillium × hagae), related to herb paris, had a genome just 4% larger than the fritillary (132.50 pg).
The Paris Japonica's genetic code is so long that researchers say it would be taller than the famed British clock tower, Big Ben, if stretched out.
Ilia Leitch, a researcher with Kew's Jodrell Laboratory, says: "We all have 46 chromosomes in our own cells. And if you took the DNA out from that and unraveled it, it would stretch about two meters. However, if you do the same for this plant, this Paris Japonica, if you unravelled all its DNA, it would stretch over a 100 meters."
"There are studies which have been done which suggest that species with very big genomes are at greater risk of extinction than those with smaller genomes, so it has that impact on that organism."
"It certainly tells us because we know of the effects of all this DNA on the plant, becuase you know they're going to take a long time to grow, we just have to look after them very carefully."
The results of her team's research are being published in the Botanical Journal of the Linnean Society. Online: http://www.kew.org