The mysteries of pear-shaped fruits and vegetables appear to have been revealed. Scientists in the US have found that disabling one gene in a tomato can make it pear-shaped. Squash, aubergines and pears, they claim, probably owe their shape to the same effect.
Writing in a recent issue of the Proceedings of the National Academy of Sciences, plant biologist Steven Tanksley and his colleagues at Cornell University, New York claim that without the gene, called OVATE, the top of a fruit grows more than the bottom, giving it a long neck and a bulbous base.
The gene probably stops growth in normal fruit by making a protein that controls other genes, said Tanksley. The model plant Arabidopsis has its own version, but nobody knew what it did.
An article in this week's issue of Nature magazine reports that plant breeders developed strains of pear-shaped tomatoes in the early twentieth century. "But at some point in the intervening 50 years the material was lost," said Tanksley. His team reinvented the trait from an existing variety.
The Nature report adds that most wild fruit - including the ancestors of cultivated crops - are small and round. An animal biting into them anywhere has a good chance of a mouthful of seeds. A long, seedless neck is a waste of a plant's resources.
According to the report we humans have a penchant for pear-shaped fruit and have bred elongated species for aesthetic reasons. Plant biologist John Doebley of the University of Wisconsin in Madison told Nature: "Humans like novelty. Rather than something practical, gardeners might just have enjoyed the curiosity value."
Full findings of the study are published in the Proceedings of the National Academy of Sciences, doi: 10.1073/pnas.162485999(2002).