The Future of Agriculture
Welcome to the Future of Agriculture and learn how biotechnology and agriculture are helping to shape the way for a sustainable future.
Published at 5:39 PM EDT on Jun 19, 2018 | Updated at 7:10 AM EDT on Jun 20, 2018
The Florida citrus industry is having their worst harvest in 73 years, and scientists at the University of Connecticut are stepping in to help.
The poor harvest is in part because of damage from Hurricane Irma, but the devastation started long before that. A disease known as citrus greening has been wreaking havoc for years. UConn researchers are working on a solution.
“Our hope is that we can modify endogenous genes in citrus to create the greening disease’s resistance,” explained University of Connecticut scientist Dr. Yi Li.
Gene editing is often discussed in terms of medical advancements and new health treatments. But gene editing can also benefit the food we eat and agriculture as well. Some of the latest developments are happening in Connecticut.
Florida citrus crops have been falling victim to the greening disease since 2005. The contagious disease is spread by a bacteria found in insects feeding off of citrus crops. The bacteria grows and spreads throughout the trees. But the process is slow – it can take up to five years after a tree is infected for it to show signs of damage. As of today, 75 percent of the Florida citrus crops have been wiped out by this quickly spreading disease that has also made its way to crops in Texas and California.
The UConn scientists are working in conjunction with the University of Florida to find a cure.
“We are basically the technology development lab,” Li said. “And then once we develop the technology people in Florida our collaborators are going to use our technology to genetically modify citrus genome.”
These small, targeted changes to an organism’s original genes produce a specific beneficial result. These genetic alterations can provide plants and animals with beneficial characteristics, just like the disease resistance seen in the citrus crops.
Helping the Florida citrus crop is only part of what’s being done here in the lab. Li and his team have also been implementing their gene editing technique on landscaping products that could soon be used in your own backyard. Their latest project? Slow growing grass.
“We started to breed them to develop these traits that we thought would be beneficial to lawn owners, homeowners, and commercial lawn care people,” explains PhD student Lorenzo Katin-Grazzini, “Such as slow growth to drastically reduce the mowing time that’s needed to really just save cost and time and energy associated with turf grass management.”
Li has also created a genetically modified burning bush, a plant often found in New England that spreads rapidly. Where it grows nothing else can, decreasing the diversity in our forests.
“They either don’t produce seeds or produce very few seeds as such that the birds cannot spread them anymore because there are no seeds,” Li said. “So we hope that those plants are going to be released through horticulture in the next two to three years.”
But the lab at UConn isn’t stopping there.
“I do want to work with more ornamental plants,” Li said. “Particularly invasive plants because I do think that has a huge impact on biodiversity on our environment so if we can use gene editing technology to make that non-invasive that’s what I would like to work on.”
Published by the CT Mirror on May 28th, 2018
To feed the burgeoning human population, it is vital that the world figures out ways to boost food production.
Increasing crop yields through conventional plant breeding is inefficient – the outcomes are unpredictable and it can take years to decades to create a new strain. On the other hand, powerful genetically modified plant technologies can quickly yield new plant varieties, but their adoption has been controversial. Many consumers and countries have rejected GMO foods even though extensive studies have proved they are safe to consume.
But now a new genome editing technology known as CRISPR may offer a good alternative.
I’m a plant geneticist and one of my top priorities is developing tools to engineer woody plants such as citrus trees that can resist the greening disease, Huanglongbing (HLB), which has devastated these trees around the world. First detected in Florida in 2005, the disease has decimated the state’s $9 billion citrus crop, leading to a 75 percent decline in its orange production in 2017. Because citrus trees take five to 10 years before they produce fruits, our new technique – which has been nominated by many editors-in-chief as one of the groundbreaking approaches of 2017 that has the potential to change the world – may accelerate the development of non-GMO citrus trees that are HLB-resistant.
GENETICALLY MODIFIED VS. GENE EDITED
You may wonder why the plants we create with our new DNA editing technique are not considered GMO? It’s a good question.
Genetically modified refers to plants and animals that have been altered in a way that wouldn’t have arisen naturally through evolution. A very obvious example of this involves transferring a gene from one species to another to endow the organism with a new trait – like pest resistance or drought tolerance.
But in our work, we are not cutting and pasting genes from animals or bacteria into plants. We are using genome editing technologies to introduce new plant traits by directly rewriting the plants’ genetic code.
This is faster and more precise than conventional breeding, is less controversial than GMO techniques, and can shave years or even decades off the time it takes to develop new crop varieties for farmers.
There is also another incentive to opt for using gene editing to create designer crops. On March 28, 2018, U.S. Secretary of Agriculture Sonny Perdue announced that the USDA wouldn’t regulate new plant varieties developed with new technologies like genome editing that would yield plants indistinguishable from those developed through traditional breeding methods. By contrast, a plant that includes a gene or genes from another organism, such as bacteria, is considered a GMO. This is another reason why many researchers and companies prefer using CRISPR in agriculture whenever it is possible.
CHANGING THE PLANT BLUEPRINT
The gene editing tool we use is called CRISPR – which stands for “Clustered Regularly Interspaced Short Palindromic Repeats” – and was adapted from the defense systems of bacteria. These bacterial CRISPR systems have been modified so that scientists like myself can edit the DNA of plants, animals, human cells and microorganisms. This technology can be used in many ways, including to correct genetic errors in humans that cause diseases, to engineer animals bred for disease research, and to create novel genetic variations that can accelerate crop improvement.
To use CRISPR to introduce a useful trait into a crop plant, we need to know the genes that control a particular trait. For instance, previous studies have revealed that a natural plant hormone called gibberellin is essential for plant height. The GA20-ox gene controls the quantity of gibberellin produced in plants. To create a breed of “low mowing frequency” lawn grass, for example, we are editing the DNA – changing the sequence of the DNA that makes up gene – of this plant to reduce the output of the GA20-ox gene in the selected turf grass. With lower gibberellin, the grass won’t grow as high and won’t need to be mowed as often.
The CRISPR system was derived from bacteria. It is made up of two parts: Cas9, a little protein that snips DNA, and an RNA molecule that serves as the template for encoding the new trait in the plant’s DNA.
To use CRISPR in plants, the standard approach is to insert the CRISPR genes that encode the CRISPR-Cas9 “editing machines” into the plant cell’s DNA. When the CRISPR-Cas9 gene is active, it will locate and rewrite the relevant section of the plant genome, creating the new trait.
But this is a catch-22. Because to perform DNA editing with CRISPR/Cas9 you first have to genetically alter the plant with foreign CRISPR genes – this would make it a GMO.
A NEW STRATEGY FOR NON-GMO CROPS
For annual crop plants like corn, rice and tomato that complete their life cycles from germination to the production of seeds within one year, the CRISPR genes can be easily eliminated from the edited plants. That’s because some seeds these plants produce do not carry CRISPR genes, just the new traits.
But this problem is much trickier for perennial crop plants that require up to 10 years to reach the stage of flower and seed production. It would take too long to wait for seeds that were free of CRISPR genes.
My team at the University of Connecticut and my collaborators at Nanjing Agricultural University, Jiangsu Academy of Agricultural Sciences, University of Florida, Hunan Agricultural University and University of California-San Diego have recently developed a convenient, new technique to use CRISPR to reliably create desirable traits in crop plants without introducing any foreign bacterial genes.
We first engineered a naturally occurring soil microbe, Agrobacterium, with the CRIPSR genes. Then we take young leaf or shoot material from plants and mix them in petri dishes with the bacteria and allow them to incubate together for a couple of days. This gives the bacteria time to infect the cells and deliver the gene editing machinery, which then alters the plant’s genetic code.
In some Agrobacterium infected cells, the Agrobacterium basically serves as a Trojan horse, bringing all the editing tools into the cell, rather than engineering plants to have their own editing machinery. Because the bacterial genes or CRISPR genes do not become part of the plant’s genome in these cells – and just do the work of gene editing – any plants derived from these cells are not considered a GMO.
After a couple of days, we can cultivate plants from the edited plant cells. Then it take several weeks or months to grow an edited plant that could be planted on a farm. The hard part is figuring out which plants are successfully modified. But we have a solution to this problem too and have developed a method that takes only two weeks to identify the edited plants.
GENETICALLY DESIGNED LAWNS
One significant difference between editing plants versus human cells is that we are not as concerned about editing typos. In humans, such errors could cause disease, but off-target mutations in plants are not a serious concern. A number of published studies reported low to negligible off-target activity observed in plants when compared to animal systems.
Also, before distributing any plants to farmers for planting in their field, the edited plants will be carefully evaluated for obvious defects in growth and development or their responses to drought, extreme temperatures, disease and insect attacks. Further, DNA sequencing of edited plants once they have been developed can easily identify any significant undesirable off-target mutations.
In addition to citrus, our technology should be applicable in most perennial crop plants such as apple, sugarcane, grape, pear, banana, poplar, pine, eucalyptus and some annual crop plants such as strawberry, potato and sweet potato that are propagated without using seeds.
We also see a role for genome editing technologies in many other plants used in the agricultural, horticultural and forestry industries. For example, we are creating lawn grass varieties that require less fertilizer and water. I bet you would like that too.