The unintended consequences of a citrus breeding programme may have produced a grapefruit those on heart medicines can safely eat.

Dr Fred Gnitter of the University of Florida has been involved in work to breed a deep red pomelo which has given rise to a grapefruit people taking cholesterol lowering medications (statins) may be able to enjoy.

'Sometimes breeders get lucky and this is one of those stories,” he told a seminar at the Zespri Momentum conference in October.

'We made crosses of a pomelo and a deep red fleshed grapefruit. One result was a red fleshed fruit which tastes and smells like grapefruit but has virtually none of the three compounds which suppress enzymes in the liver.” People taking statins are advised not to eat grapefruit nor drink its juice because they increase the absorption of the drug into the body, leading to side effects from the drug.

Fred said plant breeders have worked with scientists in a medical school to have the juice tested on human cell cultures and those tests showed it does not suppress the activity enzymes.

'What we need is some innovative company to take this on and fund human clinical studies which are needed before we can commercialise this fruit juice as safe to drink for heart patients.”

Breeding new citrus cultivars has traditionally been difficult because, despite the apparent significant variety of citrus fruits, they all come from a very narrow genetic base. Fred said now the citrus genome has been sequenced, thanks to the International Citrus Genome Consortium, the possibility of breeding new varieties resistant to some of the disease which threaten commercial crops, may be possible. The first grapefruit was found on the island of Barbados around 1700 and it was probably the result of seeds from pomelo trees brought from South East Asia. Philippe Odet, who was either a French Count or a pirate (or perhaps both, said Fred), introduced grapefruit to Tampa Bay Florida in the 1823. 'He shared seeds with friends and in 1880 a grower found a fruit which was virtually seedless. In 1929 fruit with pink flesh were found.”

However, despite the diversity, all were genetically identical.

'Sweet orange originated in South East China 3000 year ago. When we look at sweet orange we find the same sort of diversification but, just as in grapefruit, there is not a whole lot of genetic difference, which made breeding virtually impossible – that was until genome sequencing,” he said.