California Ag Network

Tag: UCR

  • Critical Groundwater Supplies May Never Recover From Drought

    Illustration of groundwater location. (USGS)

    Along with hurricanes and wildfires, there’s another important, but seldom-discussed effect of climate change — toxic water and sinking land made worse by groundwater drought. Water from snow and rain seeps deep into the ground between layers of soil and accumulates in sponge-like underground bathtubs, called aquifers. Farmers rely heavily on this groundwater to irrigate their crops when they can’t get enough water from surface water sources.

    Roughly 85 percent of Californians also rely on groundwater for some portion of their water supply. Worldwide, an estimated two billion people depend on it. However, excessive groundwater use combined with droughts has caused land surface to sink, damaging critical infrastructure including roads, buildings, and sewage and water pipes.

    New UC Riverside research shows groundwater takes an average of three years to recover from drought — if it ever recovers at all. In the largest study of its kind, scientists found that this recovery time only applies to aquifers that aren’t touched by human activity, and the recovery time might be even longer in regions with excessive pumping.

    For groundwater levels to recover after a drought, new precipitation requires time to percolate through the soil and recharge the depleted aquifer. The researchers show that this process can take several years longer in areas with deeper groundwater levels.

    “If people pump groundwater without first letting it recharge, groundwater levels keep going down, the cost of pumping goes up, and the land sinks,” explained Hoori Ajami, UCR groundwater hydrologist and study co-author and principal investigator on this project.

    Published in the Journal of Hydrology, the new study is the first to examine groundwater response to droughts on a continental scale. Previous investigations of groundwater drought have mostly relied on model simulations and covered smaller areas. This study relied on 30 years of daily measurements from 600 wells across the country.

    On average, the researchers determined it takes about two years for rainwater drought to become groundwater drought, though in some cases it takes as long as 15 years. Because of the long lag time, the effects aren’t felt or seen immediately. However, they can be severe.

    Groundwater drought combined with pumping can cause a gradual, uneven lowering of the land surface called subsidence. “It is a known problem in California’s Central Vaalley, exacerbated by climate factors and excessive water pumping,” Ajami said. “Subsidence causes irreversible damage to infrastructure, buildings and roads.”

    As the ground shifts and water level declines, contaminants in the soil, like arsenic, can mobilize and poison the water. In coastal areas, aquifers depleted by drought and pumping can fill up with salty sea water, making groundwater unusable for drinking or farming.

    “You start with a problem of water quantity, and you end up with a problem of water quality,” Ajami said.

    “Excessive pumping lowers the groundwater level, creating a downward spiral in which restoring the aquifer becomes harder and harder,” added study co-author Adam Schreiner-McGraw.

    To reduce the damage from prolonged droughts that are an inevitability as the planet continues to warm, the researchers have several recommendations. Most climate models show rain becoming more intense. Storing rain waters could recharge aquifers, speeding up the recovery process.

    The researchers also suggest that farmers improve irrigation efficiency and switch perennials like almonds, pistachios, and walnuts to annual, less water-intensive crops in areas where groundwater depletion is severe.

    “We need to improve our climate projections to include groundwater, so that we can better assess what we have and how to protect it,” Ajami said. “There are ways to better manage what we have.” — By Jules Bernstein, UC Riverside

  • NASA Funds Tiny Tomatoes for Vertical Farming on Earth and Space

    Urban agriculture offers many benefits for food production but often has higher costs relative to traditional farming and is limited to only a few crops. By 2050, there will be nine billion people on the planet, but arable land is decreasing. Global food production will need to double to meet food needs, though climate change complicates the problem more.

    Robert Jinkerson, an assistant professor of chemical and environmental engineering at UC Riverside, is working to change this by engineering the size and nutritional value of tomato plants to increase both the diversity and value of crops that can be grown in urban controlled environment agriculture, or CEA.

    Jinkerson has received a $450,000 New Innovator grant from the Foundation for Food & Agriculture Research, or FFAR, to advance this research. FFAR’s New Innovator in Food & Agriculture Research Award provides early career scientists with funding to conduct audacious food and agriculture research.

    “Urban controlled environment agriculture can offer many benefits for the production of crops and is likely to supply more food in the future as worldwide food demand increases,” Jinkerson said.

    Often these urban CEA systems are designed to have plant growth areas stacked vertically to save space. However, this also decreases the height available for plant growth, limiting the size of crops that can be cultivated in vertical farms to small leafy greens.

    “In order to overcome these size limitations and to increase the variety of crops that can be grown in vertical farms, we are engineering tomato plants to have a small stature and are optimized for this unique growing environment,” said Jinkerson, who uses CRISPR/Cas9 gene editing to modulate key genes involved in plant development and architecture.

    In addition to reducing the size of plants, this project will also increase the nutritional value of these crops by increasing their vitamin content, making urban agriculture more profitable.

    The potential applications for these tiny tomatoes don’t end on Earth.

    Jinkerson, along with Martha Orozco-Cárdenas, director of the UCR Plant Transformation Research Center, have been awarded a NASA Space Biology grant to evaluate tomatoes from their prior work on the International Space Station. These plants, also engineered with gene editing technology and dubbed Small Plants for Agriculture in Controlled Environments, or SPACE tomatoes, will be grown in the Advanced Plant Habitat onboard the ISS to determine how these plants grow in microgravity. The SPACE tomatoes will be grown ‘seed-to-seed,’ meaning seeds will be harvested and the next generation grown in space, completing an entire lifecycle. These experiments, which will happen after several years of trials on Earth, will help establish methodologies to grow food on long duration space missions.

    “We are extremely excited to receive support for these projects and hope that the results will help transform the way we produce food here on Earth and beyond,” said Jinkerson.

    About UC Riverside

    The University of California, Riverside (www.ucr.edu) is a doctoral research university, a living laboratory for groundbreaking exploration of issues critical to Inland Southern California, the state and communities around the world. Reflecting California’s diverse culture, UCR’s enrollment is more than 24,000 students. The campus opened a medical school in 2013 and has reached the heart of the Coachella Valley by way of the UCR Palm Desert Center. The campus has an annual statewide economic impact of almost $2 billion. To learn more, email news@ucr.edu.

  • Novel Treatment Causes Killer Citrus Disease to Leak & Die

    New research affirms a unique peptide found in an Australian plant can destroy the No. 1 killer of citrus trees worldwide and help prevent infection. Huanglongbing, HLB, or citrus greening has multiple names, but one ultimate result: bitter and worthless citrus fruits. It has wiped out citrus orchards across the globe, causing billions in annual production losses.

    Untreated citrus plants on the left, as compared to treated ones on the right. (Hailing Jin/UCR)

    All commercially important citrus varieties are susceptible to it, and there is no effective tool to treat HLB-positive trees, or to prevent new infections. However, new UC Riverside research shows that a naturally occurring peptide found in HLB-tolerant citrus relatives, such as Australian finger lime, can not only kill the bacteria that causes the disease, it can also activate the plant’s own immune system to inhibit new HLB infection. Few treatments can do both.

    Research demonstrating the effectiveness of the peptide in greenhouse experiments has just been published in the Proceedings of the National Academy of Sciences.

    The disease is caused by a bacterium called CLas that is transmitted to trees by a flying insect. One of the most effective ways to treat it may be through the use of this antimicrobial peptide found in Australian finger lime, a fruit that is a close relative of citrus plants.

    “The peptide’s corkscrew-like helix structure can quickly puncture the bacterium, causing it to leak fluid and die within half an hour, much faster than antibiotics,” explained Hailing Jin, the UCR geneticist who led the research.

    When the research team injected the peptide into plants already sick with HLB, the plants survived and grew healthy new shoots. Infected plants that went untreated became sicker and some eventually died.

    Arrows point to areas of fluid leakage from the bacterial cell after treatment with the antimicrobial peptide. (Hailing Jin/UCR)

    “The treated trees had very low bacteria counts, and one had no detectable bacteria anymore,” Jin said. “This shows the peptide can rescue infected plants, which is important as so many trees are already positive.”

    The team also tested applying the peptide by spraying it. For this experiment, researchers took healthy sweet orange trees and infected them with HLB-positive citrus psyllids — the insect that transmits CLas.

    After spraying at regular intervals, only three of 10 treated trees tested positive for the disease, and none of them died. By comparison, nine of 10 untreated trees became positive, and four of them died.

    In addition to its efficacy against the bacterium, the stable anti-microbial peptide, or SAMP, offers a number of benefits over current control methods. For one, as the name implies, it remains stable and active even when used in 130-degree heat, unlike most antibiotic sprays that are heat sensitive — an important attribute for citrus orchards in hot climates like Florida and parts of California.

    In addition, the peptide is much safer for the environment than other synthetic treatments. “Because it’s in the finger lime fruit, people have eaten this peptide for hundreds of years,” Jin said.

    Hailing Jin, research leading UC Riverside geneticist

    Researchers also identified that one half of the peptide’s helix structure is responsible for most of its antimicrobial activity. Since it is only necessary to synthesize half the peptide, this is likely to reduce the cost of large-scale manufacturing.

    The SAMP technology has already been licensed by Invaio Sciences, whose proprietary injection technology will further enhance the treatment.

    Following the successful greenhouse experiments, the researchers have started field tests of the peptides in Florida. They are also studying whether the peptide can inhibit diseases caused by the same family of bacteria that affect other crops, such as potato and tomato.

    “The potential for this discovery to solve such devastating problems with our food supply is extremely exciting,” Jin said. — By Jules Bernstein, UC Riverside

  • Root Bacteria Could Help Defeat Fatal Citrus Disease

    A UC Riverside-led team is looking at tiny underground microorganisms for a way to prevent a huge problem — Huanglongbing, a disease with no cure that has decimated citrus orchards worldwide.

    The disease, also known as HLB or citrus greening, has multiple names but the same ultimate result: bitter and worthless citrus fruits. By some estimates, the end of citrus orchards in California and Florida could amount to $14 billion in lost commercial revenue.

    Fruit affected by Huanglongbing. (UCR)

    “Often times, it is thought of as an above-ground disease of the fruits, leaves, and stems,” said Caroline Roper, plant pathology professor and director of the new research effort. “However, we have seen the roots of trees decline with infection, and we want to understand why.”

    The National Institute of Food and Agriculture has awarded the UCR-led team $10 million over the next five years to investigate the role of soil and root microbes in the disease.

    Roper said data from previous studies shows the microbiome of the infected tree — which includes bacteria and fungi as well as protozoa and viruses — plays a role in the disease.

    “We have seen a shift in the root microbiome as trees get sicker,” she said.

    The microbiomes shift to contain more potentially parasitic organisms that may act as secondary invaders to a tree that is suffering from HLB, according to Roper. The invasion of these root pathogens may be causing trees to die faster when they have HLB.

    Part of this new research effort will test whether soil amendments like manure and compost might suppress parasitic microorganisms in the roots as well as the soil, and give the trees more strength to combat diseases including HLB.

    In addition, the research team will try to determine the molecular basis of HLB resistance shown by citrus root stocks developed in Florida. They’ll then see how those rootstocks perform in California, which has different soil and climate conditions.

    The research team will examine both younger trees, because a lot of citrus growers have had to re-plant their orchards after infection, as well as older trees to see if mature groves can recover.

    It will also be important to note how well root stocks from Florida, where there has been a heavy infestation of HLB, perform in California, where much less of the disease has been detected.

    “One of the great things about this grant is that we’re able to leverage existing field trials being done by our collaborators in Florida and at the UC’s Lindcove Research and Extension Center in central California,” Roper said. “This may lead to faster results than we’d otherwise have had.”

    Collaborators on the project include UC Davis; California State University, Sacramento; the University of Florida; and the U.S. Department of Agriculture’s Agricultural Research Service in Ft. Pierce, Florida. — By Jules Bernstein, UC Riverside

  • Model Filter System Removes Antibiotics from Wastewater

    A model for an economical filter system that can remove antibiotics from wastewater has been designed by Agricultural Research Service (ARS) and University of California-Riverside (UCR) collaborators.

    Microbiologist Mark Ibekwe with the ARS Agricultural Water Efficiency and Salinity Research Unit in Riverside, California, and UCR soil chemist Daniel Ashworth constructed the prototype system using four layers of natural materials: gravel, sand, soil, and biochar in a column 50-cm tall and 12-cm diameter.

    They used the laboratory-scale model to remove four antibiotics: amoxicillin, cefalexin, sulfadiazine, and tetracycline at various levels of efficiency. These four antibiotics were selected for testing in the scale model because they are among the most common in wastewater treatment plant effluent. Conventional wastewater treatment plant systems are relatively effective at removing nutrients and bacteria but can be somewhat ineffective at removing antibiotics.

    The effectiveness of the laboratory-scale system varied with the antibiotic being evaluated. It successfully removed 98 percent of the tetracycline, followed by 91 percent of cefalexin, 81 percent of amoxicillin and 51 percent of sulfadiazine. The antibiotics had initial concentrations of 10 ppb, comparable to levels that have been seen in municipal wastewater.

    Amoxicillin and cefalexin removal were largely controlled by chemical degradation in the gravel layer, while sulfadiazine was largely removed by a combination of chemical and microbial degradation in the soil mixed with a biochar layer. Tetracycline was primarily removed by chemical reactions with water (hydrolysis) in the gravel layer.

    “These results show the importance of using layers of different materials to target different antibiotics rather than expecting one layer and material will be able to do the job.” said Ibekwe.

    Increasing the time it takes for the water stream to pass through the column also improved removal efficiency, especially for amoxicillin and cefalexin. In this design, the simulated wastewater enters at the bottom of the column to saturate the bottom layer and then is pumped up through the column to flow out through the top.

    A “full-size” scale-upped version of the researchers’ filter system—one that might serve a small-town wastewater treatment plant—would be about 2 meters tall and 50 cm in diameter, according to Ashworth. Of course, you could use multiples of the columns to serve a larger need and the footprint would still be relatively small, which is one of the powerful features of this system, Ashworth added.

    There are some existing systems that can remove antibiotics from wastewater, but these tend to be very expensive or require much more space. This research was published in the Journal of Environmental Chemical Engineering.

    The Agricultural Research Service is the U.S. Department of Agriculture’s chief scientific in-house research agency. Daily, ARS focuses on solutions to agricultural problems affecting America. Each dollar invested in agricultural research results in $20 of economic impact.

  • UC Riverside Discovers First Effective Treatment for Citrus-Destroying Disease

    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.

    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.

    Orange afflicted with Citrus Greening Disease. (UCR)

    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. 

    “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.”

    Hailing Jin, Geneticist, UC Riverside

    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.”

    While the long-term effectiveness of this research has not yet been confirmed or published in a scientific journal and the project is still in its early stages, Dr. Jin’s promising findings have resulted in a commercial licensing agreement between UCR and Invaio Sciences. It is not uncommon for researchers to team with commercial licensing partners during the early phases of their studies. In this case, more work still needs to be done to confirm the robustness and viability of this treatment. Additional greenhouse trials are being initiated by Dr. Jin and her team at the citrus-specific Bio-Safety Level-3 Laboratory in Riverside, California. It also is expected that field trials will be conducted to show the effectiveness of the treatment under commercial grove conditions. — By Jules Bernstein, UC Riverside

    Regarding the announcement, Marcy Martin from the California Citrus Research Board shared, “While the release was understandably enthusiastic about potentially promising research and we are heartened by the commercial interest in this peptide, we are looking forward to reviewing complete studies on the effectiveness of this therapy in greenhouse and field studies.

    Importantly, this is not the time to let down our guard.  It continues to be critical for all citrus growers in the state to remain extremely vigilant in protecting their groves against the Asian citrus psyllid and HLB. The psyllid arrived from Mexico in 2008 and is now firmly established in southern California. The first HLB-positive tree was found in residential Los Angeles County in 2012. As of July 3, 2020, 1,926 HLB-affected trees have been identified and removed to slow the spread of the disease in residential areas of Los Angeles, Orange, Riverside and San Bernardino counties. Unlike Florida, where HLB has decimated commercial citrus groves, California growers invested in research early through the CRB and have been diligent in applying best-management practices; therefore, the disease has not yet been detected in any commercial groves. The CRB will continue to focus intensive efforts on a variety of promising research to find a solution to HLB.

    Moving forward, we at the CRB are proud to work on behalf of the 3,300-plus California citrus growers to invest in key studies to find a solution to HLB. Citrus growers always have been resilient and resourceful. Together, we will look toward the horizon for a solution to HLB.

    Marcy Martin, President, California Citrus Research Board

    In the meantime, we continue to monitor and review progress in potential therapies, new HLB-resistant varieties, better psyllid control strategies and more. We are enthusiastic about the commercial interest in HLB therapies and look forward to being able to share a range of potential approaches for California citrus growers as research progresses and matures. If you have any questions or would like additional information about the status of this research, please contact CRB President Marcy Martin at 559.708.3791 or marcy@citrusresearch.org.”