University of California Riverside (UCR) scientists have discovered a molecule capable of controlling the pathogen that causes HLB/Citrus Greening – a severe plant disease carried by an insect called the Asian citrus psyllid – that has wreaked havoc across citrus farms throughout the United States and around the globe.
Asian Citrus Psyllid adults
The new treatment effectively kills the bacterium causing the disease with a naturally occurring molecule found in wild citrus relatives. The molecule, an antimicrobial peptide, offers numerous advantages over the antibiotics currently used to treat the disease. Unlike antibiotic sprays, the peptide is stable even when used outdoors in high heat, easy to manufacture, and safe for humans.
“This peptide is found in the fruit of greening-tolerant Australian finger limes, which has been consumed for hundreds of years,” explained UCR geneticist Hailing Jin, who discovered the cure after a five-year search. “It is much safer to use this natural plant product on agricultural crops than other synthetic chemicals.”
Currently, some US growers in warm, southern states such as Florida and California are spraying antibiotics and pesticides in an attempt to save trees from the CLas bacterium that causes citrus greening, also known as Huanglongbing or HLB.
“Most antibiotics are temperature sensitive, so their effects are largely reduced when applied in the hot weather,” observed Jin. “By contrast, this peptide is stable even when used in 130° heat.”
The UCR scientist found the peptide by examining plants such as the Australian finger lime known to possess natural tolerance for the bacteria that causes Citrus Greening Disease, and then isolated the genes that contribute to this innate immunity. One of these genes produces the peptide, which was then tested over the course of two years.
Improvement was soon visible: “You can see the bacteria drastically reduced, and the leaves appear healthy again only a few months after treatment,” noted Jin.
The peptide only needs to be reapplied a few times per year, making it far more cost effective for growers. It can also be developed into a vaccine-like solution to protect young healthy plants from infection, as it is able to induce the plant’s innate immunity to the bacteria. The molecule can also be applied by injection or foliage spray, and moves systemically through plants and remains stable, which makes the effect of the treatment stronger.
Worldwide license agreement
UCR has since signed an exclusive agreement with Invaio Sciences, which specialises in the direct delivery of biologics in trees to help combat disease. Under the terms of the agreement, UCR has granted Invaio an exclusive, worldwide license with the rights to sublicense its novel peptide technology to develop and deploy products as required by the industry.
Sustainable pesticide reducing solutions
Invaio Sciences has pioneered a novel approach to managing insect populations in a more sustainable and targeted way by controlling the nutritional function organ called the obligate microbial symbiont (OMS) to alter insect health. This new approach, coupled with a deep understanding of the inner workings of insects by the company’s diverse team of scientists, holds the potential to dramatically reduce the need for pesticide use globally, benefiting agriculture, public health and the environment.
Citrus Psyllid adults which spread HLB, also known in China as yellow dragon disease
Invaio says its focus on precision delivery allows the company to take a more mindful approach to insect management. For biological delivery, Invaio leverages naturally derived systems that can be used to produce, protect, and deliver a variety of active molecules, all of which are biodegradable. It has also developed a physical delivery system built upon proprietary 3D-printed injection tips that deliver biological active molecules into a crop vascular system, where they rapidly move throughout the plant for maximum protection.
Californian connection
While the need for an HLB cure is global, it is also particularly strong within UCR’s home state, as California produces 80% of all fresh citrus in the US, according to Brian Suh, director of technology commercialisation in UCR’s Office of Technology Partnerships.
“This license to Invaio opens up the opportunity for a product to get to market faster,” said Suh. “Cutting edge research from UCR, like the peptide identified by Dr. Jin, has a tremendous amount of commercial potential and can transform the trajectory of real-world problems with these innovative solutions.”
“Invaio is enthusiastic to partner with UC Riverside and advance this innovative technology to develop solutions for combating the disease HLB/Citrus Greening,” added Dr Gerardo Ramos, chief science officer at Invaio Science, which is based in Basel, Switzerland.
“Our novel approach with a focus on natural-based solutions in connection with plant and soil health will revolutionize agricultural practices in far more beneficial ways for the health of people and the planet. This relationship with UC Riverside will allow us to continue to learn from nature and enable biologicals to perform in a sustainable and reliable way. The prospects of addressing this type of incurable devastating crop disease to help agricultural communities and improve the environmental impact of production is exciting and rewarding.”
Prize winner
Meanwhile another company working on a cure for citrus greening has been boosted with the recent awarding of Alexandria LaunchLabs’ US$100,000 AgTech Innovation prize. The North Carolina-based winner, TerMir Inc, is pioneering an innovative and environmentally safe treatment for the devastating disease. TerMir’s systemic formulation breaks the disease cycle by eliminating bacteria within a tree’s vascular system.
