We Could Soon Be Eating Apples With Red Flesh

An apple with red flesh. Plant & Food Research

Apples with red flesh and other novel fruit varieties may soon be making their way to a supermarket near you thanks to new planet breeding techniques that mimic DNA mutations that occur in nature, according to scientists from Plant & Food Research (PFR) in New Zealand.

The techniques allow us to easily manipulate the look, feel, taste and nutritional content of fruit and vegetables to rapidly create higher quality products.

Most of the nutrients and vitamins in products such as apples and potatoes, for example, are found in color compounds, or pigments, that are concentrated in the skin. But by manipulating a family of proteins called "MYB transcription factors" which switch other genes "on or off", scientists can produce these healthy compounds throughout the fruit, including the flesh.

This could be done using gene editing techniques such as CRISPR/Cas9, which essentially allows scientists to "copy and paste" DNA code.

In an article published in the journal Trends in Plant Science, research scientists Andrew Allan and Richard Espley from PFR reviewed research into MYBs which are associated with the development of biological signaling and pigmentation in plants.

"Studies have shown that pigments such as anthocyanins and carotenoids are thought to offer health and dietary benefits," Allan said in a statement. "Changes in key MYB transcription factors could turn the colorless flesh of certain fruits into one with color. "It could significantly increase the content of pigments per fruit serving, resulting in a possible step change in health benefits."

Aside from influencing color, MYBs are also involved in taste, flavor and aroma, as well as the texture of the flesh and the formation of hair on the skin.

Breeding new categories of fruits and vegetables with improved appearance, flavor, texture, and storage abilities, among other desirable traits could encourage the consumption of more plant products, thus benefiting public health, according to the researchers.

While breeding based on color and taste is a very old technique, breeding with markers targeted at MYBs only began around a decade ago. Furthermore, manipulating MYBs with gene editing has only been taking place for less than five years, Allan told Newseek.

Foods such as red and white grapes, blood oranges and purple rice all owe their unique differentiating characteristics to naturial variations in MYBs. But the new techniques essentially speed up this natural process.

"Waiting for a natural variant in a MYB to arise—due to sunlight or changes during crossing one plant with another—takes many years," Allan said. "This happens—DNA changes naturally with time. But gene editing can induce a change right next to a MYB (next to its DNA sequence) to enhance its activity, or right in the MYB sequence (to reduce its activity)."

"These new breeding techniques allow new plant varieties to be made which will give consumers more choice," Allan said. "Many of these will have measurable increases in nutritional content. Increases in yield are possible, helping in areas where food is in shortage. Plants can [also] be adapted faster, to changing climate, with new breeding methods."

Other new plant breeding methods could be beneficial for different reasons. A method dubbed "speed breeding," for example, can grow crops several times faster than traditional methods, which could help to feed the world's rapidly expanding population.

The process outlined in the journal Nature Plants helps plants to grow quicker by putting them under a special lighting system that is enhanced for photosynthesis.