Can you imagine life today without the lemon and orange juice? Europeans and Arabs brought the citrus fruits during the Middle Age from the Far East and India, that's why it was believed for a long time that South/Southeastern Asia is the place of origin for these fruits. But a new research made at the Center for Plant and Food Science at the University of Western Sydney shows that the citrus fruits originated in fact in Australia, New Caledonia (off eastern Australia) and New Guinea.
The team made by the Australian Professor David Mabberley, from the University of Washington and an adjunct professor at UWS and Professor Andrew Beattie from the Center for Plant and Food Science, shows that the first species of citrus might have grown in North-Eastern Australasia and were spread as 'floating fruit' on westward-flowing equatorial currents, some 30 million years ago.
"Conventional wisdom holds that citrus evolved in Southeast Asia but this is based on ignorance about what constitutes a true species, the relationships between plants in Asia and Australasia, and how the two landmasses were related prior to the discovery of plate tectonics in the 1960s," said Mabberley, also a Soest Professor and Director of the Botanic Gardens in Washington.
The team made extensive research on plant taxonomy and the species' evolution and dispersal.
"There are about 25 true species of citrus and some 50 % of these are from New Guinea, New Caledonia and Australia. While most commercial species and cultivars such as mandarins, oranges and lemons, originated in Asia," said Mabberley.
"Recent molecular studies have helped to resolve gaps in the evolution and domestication of citrus. These studies indicate that the closest relatives to the citron, citrus medica - long-considered to have originated in India and one of the parents of the lemon - are species from New Ireland (off eastern New Guinea) and others from New Caledonia," said Mabberley.
"Correct identification of species and varieties of citrus and where they originated is a fundamental aspect of biosecurity for the Australian citrus industry and for current research at UWS on a devastating disease of citrus known as huanglongbing." said Beattie.
Huanglongbing (citrus greening) has been devastating Asian plantations since early 20th century.
"It is not present in Australia but is nearby in Papua New Guinea and is, after its recent introduction to Florida in the US and Brazil, a major threat to the very survival of the citrus industries of these countries. It is the greatest threat to the viability of the Australian citrus industry that I know of." said Beattie.
"Our capacity to minimize the impact of citrus greening requires a very sound knowledge of the plants affected and their suitability as hosts of the disease and its two known insect vectors - one from Africa, the other from Asia. At this point our capacity is gravely limited by surprisingly poor naming of the plants; with about a thousand scientific names in use - often with many names referring to the same plant - there is considerable confusion that inhibits our ability to fight the disease." said Mabberley.