In a previous article, we went into the research Esther van der Knaap is doing on the ancestors of our current tomato. Over time, people have selected for traits that are favorable to them, but not necessarily to the plant. Adaptation and disease resistance has been sacrificed for other desirable traits, for instance. It's possible to introduce disease-resistant genes from distant wild relatives, but there's a catch: societies aren't too keen on allowing genome editing and genetically modified organisms.
First a bit of Genetics 101. "A gene is a unit that's required, basically, to make eventually a protein that does X/Y/Z in the cell. It consists of introns and exons, as well as promoters and other regulatory elements around it", Esther explains.
"All the regulations happen in the promoter, not in the gene itself, not in the protein itself, but in the promoter. If you enhance it a little bit, then you end up with a resistant plant, or a bigger fruit, or whatever."
In order to make the necessary enhancements, being able to do genome editing would be hugely helpful, according to Esther. However, that's not currently possible, due to the regulatory restrictions surrounding genome editing. "There's the regulations and the public perception that anything modified by a vector or foreign DNA that goes into a plant is somehow bad. It's not always bad; it actually can be enormously beneficial to secure food production and make plants and crops more resilient to weather and pathogens."
"Editing is the way of the future"
Still, the know-how exists, and gene-editing technology is continuously being improved upon. "Genetic engineering and CRISPR technologies are incredibly powerful. We could basically change anything we want, and it's much faster."
Gene-mapping will always take time - finding a useful gene can take six years. And when it comes to resistance, Esther explains, "we need to cross very different tomatoes that will require a lot of additional crosses to remove all the negative baggage because the plants that have resistance are so long ago diverged from the tomato. Those diverged plants are not at all amendable to cultivation. No grower wants to grow them because they are too weedy and no consumer wants to purchase tiny fruits".
But CRISPR and GMO can at least help speed up the process. "Once I know 'this is the gene', if I wanted to introgress that useful allele into an elite variety, it's probably three years of mass backcrossing, selections, trying to break linkage with the unfavorable alleles, while by GMO or editing you could do it in six months, and without what is called linkage drag", Esther explains. "So I think that GMO and editing is the way of the future, and you can do that without leaving almost any foreign DNA in the plant."
Education against misinformation
We've already seen that the biggest roadblock to the use of genome editing is public perception. And that public perception is fed by what Esther calls "an enormous amount of misinformation as well as lack of knowledge."
With grant money coming from the American government, part of her job is to reach out to the community. For instance, with colleagues, she organized a workshop for high school students on genomes. "The editing comes into it too, but I've learned that a lot of students don't even know what a genome is, or what a gene is, and how much information is in genes that can be manipulated. There's a real lack of information and teaching of science to high school students in general. They don't learn the basics of a genome, so it's not strange that they have difficulty understanding the science behind GMO and genome editing, so they don't want it. We need to do a much better job very early on in education just explaining what DNA is, what it does and how it functions."
As far as Esther is concerned, educating the future generation of consumers can't start early enough. "We should start in elementary school with training the next generation about crop modifications and where our food comes from. If you change the public’s perception, you change everything. If the public demands a certain product, it can happen. It can be a market-driven movement, and then the government can focus on keeping the public safe. We don’t want to create plants that become invasive or take over natural populations."
And there's a task for the scientists themselves too. "It's also the fault of the scientists that do not explain clearly enough what it is they do", Esther says. "I've come to realize that the lack of training of students is so enormous that it's not easy for me to just go into a classroom for an hour and explain, because it actually requires a whole course to high school students up to speed."
More editing, less spraying
So consumers have a huge part to play in enabling GMO and genome editing, but what's in it for them?
Esther gives this example: "Who would be against a genetically modified tomato that's now resistant to a certain pest, so they don't need to spray anymore? But not many companies are going to invest in that, because then they can't sell their pesticide or herbicide anymore. So if the general public is against all forms of GMO and genome editing, then you're only helping companies that sell a product too.
"Society benefits if we spray less pesticides. Period. And if you, as a consumer, want this or that trait, buy the product. And if they don't have it, ask your grocery store, 'I would like to have this GMO'", Esther says, laughing.
"Consumers have a lot of power. If they don't buy it anymore, then the product goes out. If they do actively seek it out, the product stays."
"GMO needed to save industries"
When it comes to reducing pesticide use through GMO and genome editing, Esther says: "I would think that we can control every virus. Because if you express the coat protein, the virus cannot reproduce, and that's the end of the virus." She points to the Rainbow papaya as an example. This fruit was genetically engineered to be resistant to the papaya ringspot virus. "It expresses its coat protein, and that leads to gene silencing. So as soon as the virus comes in a cell and the coat protein is already expressed, it gets silenced by the plant machinery."
In principle, every virus could be dealt with that way. "You could look for resistance in wild relatives, but that's a lot of work if suddenly a new virus emerges and you have to cross it in all your varieties. If you just express the coat protein, you're done" - a process that only takes about a year.
"As a society, we have to come to terms with the fact that some GMO is needed to save industries as happened to the papaya industry in Hawaii. We also need to become a more sustainable society, and GMOs can help", Esther concludes.