California Ag Network

Tag: UC Davis Department of Plant Sciences

  • UC Davis Seeks Mighty Bacteria-Resistant Lettuce

    Maeli Melotto and her team at the UC Davis Department of Plant Sciences are looking for strains of lettuce that are genetically stronger at resisting bacteria that can make people sick. Their work has led to the identification of a gene that could play a role in the plant’s susceptibility to E. coli, a bacterium that causes potentially lethal intestinal illness.

    If the team could develop lettuce that can fight off the bacterium, that would avoid thousands of cases of sickness each year, cut production costs for farmers and save millions of dollars in public health expenses.

    Lettuce “sweats” substances onto the surface of leaves that E. coli and other bacteria can eat. In addition, bacteria can live just below the surface of lettuce leaves. Melotto, a professor specializing in the interactions between plants and microbes, is studying the genetic factors that determine how long bacteria can endure in the leaves. She and her team looked at more than 300 samples of lettuce and how they react to the pathogens, identifying the gene responsible for letting them in.

    Their next step is to test whether removing that gene could make lettuce more resistant to bacteria.

    Maeli Melotto, a professor in the UC Davis Department of Plant Sciences, and her team have found a gene she thinks governs whether lettuce can resist bacteria such as E. coli. (Trina Kleist/UC Davis)

    Some lettuce more likely to “feed” bacteria

    In a related study, Melotto’s team is looking at the surface of lettuce leaves and the layer just below the surface, which has tiny spaces where bacteria can live. The researchers want to learn what natural chemicals are in these two areas, and what compounds lettuce releases onto the surface of leaves that bacteria can use as food. Melotto expects to find that some types of lettuce are genetically disposed toward “feeding” bacteria.

    Melotto presented her findings at meetings earlier this year of the California Specialty Crops Council and the California Leafy Greens Research Board. Her work is funded in part by a five-year grant from the National Institute of Food and Agriculture.

  • Vertical, Indoor Farming Boosts Yield and Anti-Cancer Nutrition of Watercress

    How does it sound to grow plants without sunlight or soil, in racks going up and down instead of in rows on the ground? That’s how crops grow in indoor vertical farms, where nutrient-rich, recycled water feeds plants under red and blue LED lights. This innovative approach gives farmers the chance to alter crops as they like, whether that means making lettuce red or producing extra-flavorful herbs. The added benefits: Amid continuing drought across the western United States and water scarcity in many other parts of the world, this system uses up to 95% less water than traditional farming. And, it has no need for pesticides.

    Watercress is an ideal crop for vertical farming. Traditionally, this semi-aquatic, leafy green from the nasturtium family grows in high-quality chalk streams in Europe. It’s also packed with nutrients, with a distinctive peppery taste that makes it a yummy addition to salads. The flavor hints at anti-cancer benefits conferred by the same natural chemical compound that creates watercress’s flavor

    Now, scientists from the UC Davis Department of Plant Sciences have discovered that watercress grown in indoor, vertical farms has the highest phytonutrient content and yield, compared to cress grown in soil in California and in traditional, outdoor farms in the United Kingdom, according to a study just published in Scientia Horticulturae. Levels of the plant’s anti-cancer compound also were further elevated by increased blue light when grown indoors. This discovery shows how the quality of food can be improved for people’s health when crops are grown indoors.

    This work has been made possible with a new, specialized growing facility on campus for research in controlled environment agriculture. Multiple faculty members in the College of Agricultural and Environmental Sciences are working in this area. The indoor farm also is being used to train the next generation of high-tech farmers, with students visiting the facility and growing red romaine lettuce this year. — By Yufei Qian & Lauren Hibbert, UC Davis

  • Almond Orchard Recycling a Climate-Smart Strategy

    Recycling trees onsite can sequester carbon, save water and increase crop yields, making it a climate-smart practice for California’s irrigated almond orchards, finds a study from the University of California, Davis.

    Whole orchard recycling is when old orchard trees are ground, chipped and turned back into the soil before new almond trees are planted.

    The study, published in the journal PLOS ONE, suggests that whole orchard recycling can help almond orchards be more sustainable and resilient to drought while also increasing carbon storage in the soil.

    “To me what was really impressive was the water piece,” said corresponding author Amélie Gaudin, an associate professor of agroecology in the UC Davis Department of Plant Sciences. “Water is central to how we think about agriculture in California. This is a clear example of capitalizing on soil health. Here we see some real benefits for water conservation and for growers.”

    Burn vs. turn

    Drought and high almond prices have encouraged higher rates of orchard turnover in recent years. The previous practice of burning trees that are no longer productive is now restricted under air quality regulations, so whole orchard recycling presents an alternative. But how sustainable and effective is it for the environment and for farmers?

    For the study, scientists measured soil health and tree productivity of an almond orchard that turned previous Prunus woody biomass back into the soil through whole orchard recycling and compared it with an orchard that burned its old trees nine years prior. 

    They also experimentally reduced an orchard’s irrigation by 20 percent to quantify its water resilience.

    Their results found that, compared with burn treatments, whole orchard recycling can:

    • Sequester 5 tons of carbon per hectare
    • Increase water-use efficiency by 20 percent 
    • Increase crop yields by 19 percent


    “This seems to be a practice that can mitigate climate change by building the soil’s potential to be a carbon sink, while also building nutrients and water retention,” said Gaudin. “That can be especially important as water becomes more limited.”

    Study co-authors included Emad Jahanzad and Kelsey Brewer of UC Davis; Brent Holtz, Sean Hogan and Cameron Zuber of UC Agriculture and Natural Resources’ Cooperative Extension; and David Doll, who was formerly with UC Cooperative Extension.

    The study was funded by a Specialty Crop Block Grant Program of the California Department of Food and Agriculture and the Almond Board of California. — By Kat Kerlin, News and Media Relations, 530-752-7704, kekerlin@ucdavis.edu