New work on citrus genome opens up limonoid opportunities?

Related tags Citrus Ars

US researchers open up potential opportunities held in the citrus
genome, helping to detect specific genes related to pathogen
resistance and to high flavonoid and nutrient levels.

Scientists at the University of California-Riverside (UCR) have been gathering data on fruits, vegetative tissues, and seeds showing the diversity of the citrus links for over a century.

But only recently, researchers set out to determine the connections among the hundreds of citrus accessions-to see which ones were genetic duplicates and which were novel and distinct.

The genus Citrus​, that includes oranges, grapefruits, lemons and limes, has about 16 species, with hundreds of distant relatives, such as pummelos, trifoliate oranges, and kumquats.

The Holy Grail for improved sales, food and drinks firms are leaping to formulate products that meet growing consumer concerns over health.

In 2003, sales of functional foods and drinks were estimated to be over six times the value of those in 1998.

Unravelling the potential of health boosting components in the citrus family could lead to new gains.

Citrus fruits are abundant in limonoids, phytochemicals that scientists are currently investigating for their anti-viral, anti-fungal, anti-bacterial and anti-malarial powers. Limonoids have also shown effectiveness as insecticides both in traditional farming cultures and modern biochemistry labs.

The US government-funded Agricultural Research Service​ (ARS), involved in tracking the genes, reports that the set of genetic data they generated was one of the largest ever compiled of its kind.

"Now we have a relatively small core subset that represents much of the diversity in the Citrus genome. This makes it easier to search for specific genes,"​ says research leader and plant pathologist Richard F. Lee.

For their work, the researchers used 25 molecular markers, thirteen of which they created, to help them track genetic similarities between data in the gene bank.

According to ARS, the markers helped the researchers identify specimens of unknown origin and differentiate between closely related species.

Of the roughly 900 total accessions, about 400 of which unknown, sexual origin were studied. The others were either known to be crosses from breeding programs or mutations from a parent tree.

"About 50 of the 400 accessions represent more than 90 per cent of the collection's true diversity,"​ says ARS horticulturalist Robert R. Krueger. "That's just 13 per cent of the collection."

In the food industry, the appeal for citrus flavours appears to growing from strength to strength.

Soft drinks giant Coca Cola, for example, recently launched a lime-flavoured version of its flagship beverage.

In the past two years lemon was the most popular flavour, but this is now changing to cold-pressed lime, says Scott May, global product manager citrus at Quest International.

"Growth from the flavour icon perspective is lime, as well as other flavours that are refreshing,"​ he told recently.

At the beginning of the year, Quest launched a new Citrusense range with 'real, authentic flavour profiles' onto the global market based on cold-processed ingredients.

Cold-pressed citrus fruit oils are more aromatic than their distilled equivalents but they are unstable. May claims the new range "can deliver the aromatic profile with up front notes while at the same time providing stability for the flavour in applications."

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