Tuesday, 27 July 2010
Melon's Sister an Ozzie
A lot of domenticated plants have their origins in central America or the Middle East. The fig is perhaps the first to be harnessed, in a village near Jericho some 11,000 years ago. Cereals came a thousand years later. The melon may have its origins in the great southern land.
A recent paper published in the Proceedings of the National Academy of Sciences of the United States of America (PNAS) explores the origins of the cucumber and honeydew melon. The work is nicely summarised in a ErekaAlert issued last week, based on an interview with one of the author's Susanne Renner.
It's worth noting up front that the study used preserved plants from the Munich Herbarium and Botanical Garden. Many of the plants sequenced were collected from India, Vietnam and Australia in the nineteenth and twentieth centuries, some from places where these species no longer survive today. Cucumis debilis, for example, was collected in 1931, from what is now a suburb of Hanoi and can no longer be found there.
Apparently the cucumber is one of the top ten crop plants in the world based on economic importance. Who would have thought? The honeydew melon, on the other hand, is only of 'considerable agronomic significance'.
Professor Renner says that Cucumis is popular with botanists too - the domestic cucumber was "the seventh species of flowering plant to have its genome sequenced completely".
Renner says that the story of Romans cultivating cucumbers is simply wrong and has already been disproved. Prior to her study, most scientists punted on Africa being the origin of the humble melon.
However based on their DNA, the wild relatives of these two Cucumis species - Cucumis sativus, the cucumber, and Cucumis melo, the honeydew melon - lived in Asia and Australia. Of course they may have had assisted travel to other countries before domestication...
The Himalayas seem to be the most likely location for the ancestral populations to all the domesticated forms.
Eastern Himalayas is home to Cucumis hysterix, the closest living relative to the garden cucumber. However there was a surprising diversity of Cucumis melo found in India and China, and "the closest living wild relative of the cultivated melon is a native of Australia", Cucumis picrocarpus.
An added bonus to the study has been the discovery of nine new species of Cucumis, out of the 25 they sequenced. These will be described soon in an appropriate scientific journal.
Image: The 'flower' at the top of the posting was created from a (water)melon, Sabah style, as illustrated below...