Some of Your Favorite Foods are in Trouble – But Science Can Help

Can you imagine a world without bananas, oranges, coffee or chocolate?

Not happily, I suspect. Yet these iconic crops – all near and dear to people’s hearts, not to mention their stomachs and wallets – are currently threatened by a variety of deadly foes. In each case, however, plant scientists are working hard to save them with the latest tools science has to offer like genetic modification (biotechnology) and gene editing.

Farmers have used a variety of plant breeding methods to change the genetic makeup of crops since domestic agriculture began 10,000 years ago. Every fruit, vegetable and grain that is commercially available today has been altered by human hands – which debunks the idea of “natural” foods.

Traditionally, new varieties are developed by selectively breeding plants that exhibit a desirable trait, like insect resistance. But DNA from the parents recombines randomly, and often the desired traits show up in the offspring along with traits that aren’t as desirable, like lower yields.

In the 1980s, plant scientists like me learned how to use biotechnology to transfer a desirable trait from one plant species directly into the genome of another plant species – in other words, genetically modifying a plant’s DNA to include the improvement without the extra baggage. Not only does genetic modification have a flawless safety record after 20+ years of commercial use, it has already been used to save one treasured crop – the Rainbow papaya – from being wiped out by a virus. 

Now gene editing is the newest technique in the long evolution of plant breeding. Developed about 10 years ago, gene editing is different than genetic modification in that it does not involve a transfer of genetic material between species. Instead, it allows scientists to make precise and targeted improvements within a plant’s own DNA. Much like genetic modification, the goal of gene editing is to make plants more resilient, more productive, or more nutritious. Regardless of the method, plant scientists around the world are exploring how these breeding tools can help rescue each of the precious foods discussed below.      

Bananas

The banana is the world’s most popular fruit. In many countries it’s also a vital source of income and food security, accounting for up to 25 percent of daily calorie intake.  

But for several years the Cavendish variety– the kind Americans and Europeans eat and that dominates global trade – has been under attack by a fungus marching across Australia and Asia. Recently, that fungus has also established itself in Africa and the Middle East.

The fungus is another strain of the same “Fusarium wilt,” also called “Panama disease,” which nearly wiped out the Gros Michel variety -- the predecessor of the Cavendish -- in the first half of the 20th century. Efforts are being made to stop the fungus’ spread, but those efforts could easily fail – leaving the enormous Cavendish crop of Central and South America extremely vulnerable.

As I see it, two solutions are needed. One: Use the banana’s own genetic diversity to breed new marketable strains. Two: Genetically modify the Cavendish in a way that protects it.

Thankfully, both strategies are being pursued. But “the best hope,” as this Washington Post story says, seems to lie with a Cavendish modified with a gene from a variety of banana that grows wild in Indonesia and Malaysia. The gene provides the plant with a natural resistance to the fungus. Results from the initial trials, the story reports, have been “extremely positive.” 

Oranges

Since 2005, a deadly tree disease called “citrus greening” has been morphing Florida’s oranges into pathetically small, green versions of themselves. Ninety percent of the state’s groves are now infected. Production has been crushed; so have revenues. The disease is spreading in California, Georgia, Louisiana, South Carolina and Texas as well.

Citrus greening is caused by a bacteria spread by “jumping plant lice.” It cripples citrus trees’ ability to produce fruit and eventually kills them. An orange tree genetically modified to resist the bacteria would be a possible solution, but that approach is too time-consuming for a problem this urgent. Consumer receptivity could also be a challenge. That’s why Southern Gardens Citrus, one of the state’s largest producers, is testing a different approach: a virus genetically modified to kill the bacteria.

The virus is common and harmless. It’s modified to include genes from a spinach plant that code for proteins that destroy the killer bacterium. Then it’s delivered into the tree through a graft of a branch containing it.  

Field tests already conducted in two Florida counties have “not detected any negative impacts on the environment,” the U.S. Department of Agriculture said last year. According to some reports, USDA approval for broad use of the GM treatment could come as early as next year.

Coffee

Coffee, the world’s most popular drink, is also a key source of income in dozens of impoverished countries. Unfortunately, Coffea arabica, the most popular species, is the most vulnerable to disease.

Coffea arabica has low genetic diversity – 1.2 percent, compared with more than 20 percent for rice and soy – making it highly susceptible to a variety of threats. Leaf rust, caused by a fungus, is a continual worry; in 2008, it wiped out 40 percent of the crop in Colombia. At the same time, climate change effects such as increased heat and reduced rainfall are increasing stress on the plant. No wonder reports like this one – “Why the end of the world’s most popular coffee could be nigh” – are popping up.

The industry needs to develop new C. arabica cultivars that include traits like pest and disease resistance, drought tolerance, or frost tolerance. Producers are searching for answers by cross-breeding, but that’s a particularly slow and unprecise process with coffee trees. Genetic modification would provide a more timely solution. And the technology needed to make those improvements is already available.

Chocolate

Like coffee, chocolate is made from a tree – the Cacao – that is as delicate as it is precious. Theobroma cacao has limited genetic diversity and faces threats from insects, fungi and viruses that are amped up by climate change. More than half of the world’s chocolate now comes from just two African countries – Ivory Coast and Ghana. But those areas “won't be suitable for chocolate in the next few decades,” as this article notes, because of climate change.

As with coffee, cross-breeding is too slow to deal with the problem effectively. So Mars, Inc., the maker of M&M’S® and many other chocolate brands, has partnered with the Innovative Genomics Institute, a research lab at the University of California Berkeley, to develop trees with the resistance to fungi and viruses needed to let growers keep them where they are. Their main technology in this effort is the gene editing tool, CRISPR-Cas9, which enables them to remove, add, or alter sections of an organism’s DNA.

These are just a few examples of the kind of immensely important benefits genetic modification and gene editing can offer in the years ahead.

I could easily come up with many more. The question is: will society let us use this innovative science to address our problems? I hope so. Several of our favorite foods may not survive without it.