A Solution for the devastating bacteria causing citrus huanglongbing?

UC Riverside scientists have found the first substance capable of controlling Citrus Greening Disease, which has devastated citrus farms in Florida and also threatens California. 

Oranges afflicted with Citrus Greening Disease. (UCR)

The new treatment effectively kills the bacterium causing the disease with a naturally occurring molecule found in wild citrus relatives. This molecule, an antimicrobial peptide, offers numerous advantages over the antibiotics currently used to treat the disease.

UCR geneticist Hailing Jin, who discovered the cure after a five-year search, explained that 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,” Jin said. “It is much safer to use this natural plant product on agricultural crops than other synthetic chemicals.”

Currently, some growers in Florida 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. 

The Asian citrus psyllid, pictured here, spreads the bacterium that causes Citrus Greening Disease. (Mike Lewis/UCR)

“Most antibiotics are temperature sensitive, so their effects are largely reduced when applied in the hot weather,” Jin said. “By contrast, this peptide is stable even when used in 130-degree heat.”

Jin 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 she isolated the genes that contribute to this innate immunity. One of these genes produces the peptide, which she 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,” Jin said.

Because the peptide only needs to be reapplied a few times per year, it is highly cost effective for growers. This peptide 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.

Jin's peptide can be applied by injection or foliage spray, and it moves systemically through plants and remains stable, which makes the effect of the treatment stronger.

The treatment will be further enhanced with proprietary injection technology made by Invaio Sciences. UC Riverside has entered into an exclusive, worldwide license agreement with Invaio, ensuring this new treatment goes exactly where it's needed in plants. 

“Invaio is enthusiastic to partner with UC Riverside and advance this innovative technology for combating the disease known as Citrus Greening or Huanglongbing,” said Invaio Chief Science Officer Gerardo Ramos. “The prospect of addressing this previously incurable and devastating crop disease, helping agricultural communities and improving the environmental impact of production is exciting and rewarding,” he said. “This is crop protection in harmony with nature.”

The need for an HLB cure is a global problem, but hits especially close to home as California produces 80 percent of all the fresh citrus in the United States, said Brian Suh, director of technology commercialization in UCR's Office of Technology Partnerships, which helps bring university technology to market for the benefit of society through licenses, partnerships, and startup companies. 

“This license to Invaio opens up the opportunity for a product to get to market faster,” Suh said. “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.”

UV Riverside news release:

https://news.ucr.edu/articles/2020/07/07/uc-riverside-discovers-first-effective-treatment-citrus-destroying-disease

There is culture in agriculture. Mary Lu Arpaia says she spent hours looking at the avocado pictures, along with those of other fruit crops.

The USDA Pomological Watercolor Collection is one of the most unique collections in the Rare and Special Collections of the National Agricultural Library (NAL). As a historic botanical resource, it documents new fruit and nut varieties, and specimens introduced by USDA plant explorers from the late 19th and early 20th centuries.

The collection spans the years 1886 to 1942. The majority of the paintings were created between 1894 and 1916. The plant specimens represented by these artworks originated in 29 countries and 51 states and territories in the U.S. There are 7,497 watercolor paintings, 87 line drawings, and 79 wax models created by approximately 21 artists.

Lithographs of the watercolor paintings were created to illustrate USDA bulletins, yearbooks, and other publications distributed to growers and gardeners across America.

Today, the collection is preserved in NAL's Rare and Special Collections, where it serves as an important research tool for a variety of users, including horticulturists, historians, artists, and publishers. In 2010 and 2011, the entire printed collection was digitized to improve public access to this valuable resource, and to better preserve the paintings by reducing the need for researchers to handle them. Today, the whole collections is searchable.

In 1886, the United States Department of Agriculture (USDA) established the Division of Pomology to oversee the collection and distribution of new varieties of fruits, and to disseminate information to fruit growers and breeders. USDA commissioned artists to create technically accurate illustrations of newly introduced cultivars for the division's publications. In 1887, William H. Prestele was appointed as the first artist for the Division of Pomology. Henry E. Van Deman, division chief, explained the importance of Prestele's appointment in his 1887 Report of the Pomologist:

Over the years, other artists were also assigned to the division and their watercolors were used for lithographic reproductions in USDA publications and as scientific documentation of research results. Although some of the watercolor paintings are not signed, we know of 21 artists (nine of whom were women) who contributed to this important resource.

Lamb's Lemon.  Whatever happened to it?

Why are avocado roots coarse, but dense, while grass roots are a fine mat?

It has long been one of the best kept secrets in the underground world: what determines the variation in form and function of plant roots? An international team of researchers, led by scientists from Wageningen University & Research and the German Centre for Integrative Biodiversity Research in Halle-Jena-Leipzig, has revealed the strategies that roots use to invest in their tissues: do-it-yourself or outsourcing. In Science Advances they present a new framework that allows us to understand the variation in form and function in roots. “It felt like discovering a hidden treasure”.

Plants, like many other organisms, follow rules of economics when investing in their tissue. The currency is not money, but carbon and nutrients. This economics gradient flows from ‘live fast, die young' such as the Lathyrus or ginkgo, to ‘slow and steady' as the oak does. This economic theory works well for leaves. It was long assumed that the same principle applied to the roots, but researchers' efforts to deliver proof, failed repeatedly.

Each of us had a piece of the puzzle, but no-one had the whole picture. There it is: You can do it alone, or work together. Plants are just like humans. Liesje Mommer

A new collaboration gradient: an onion outsources

This problem has now been solved using a database of root characteristics of 1781 plant species from around the globe. In addition to the classical ‘fast-slow' gradient, there is a second, independent axis that is essential in understanding the form and function of plant roots. This axis is the ‘operational' gradient for nutrient uptake. It goes from a do-it-yourself strategy with many thin roots, such as followed by the cuckoo flower, to a policy of outsourcing, such as the onion. The onion collaborates intensively with soil fungi, forming a partnership of roots and fungi (mycorrhiza). “Roots that work together with fungi must make room for an 'exchange counter' - sugars go from the plant to the fungi and nutrients go the other way around. That "counter" takes up space in the outer cells of the root, which are therefore thicker than in "do-it-yourselfers", says Prof. Liesje Mommer of Wageningen University & Research. “This new operational axis shows how roots have different ways of functioning.”

Figure: Plant root strategies. Plant roots worldwide vary in their strategy for obtaining nutrients. Do-it-yourselfers have all their equipment on baord. Outsourcers form alliances with soil fungi in exchange for sugars.

This new framework for understanding variations in root characteristics offers recommendations to better understand the way roots work. This insight is useful in future research to predict the subterranean plant response to changing environmental conditions, or to launch new breeding programmes.

Unearthing treasure

Professor Liesje Mommer on how the project was started: “It was a collaboration between renowned researchrs from Europe and the United States, during an inspiring workshop in Leipzig. We knew a treasure was buried underground near the plant roots, and that finding it required collaboration. Each of us had a piece of the puzzle, but no-one had the whole picture. There it is: You can do it alone, or work together. Plants are just like humans.”

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