Melotto works toward sustainable food systems around the world

UC Davis research on how to keep leafy greens safe for people to eat was featured at a recent international meeting aiming to transform the world’s food systems.

Maeli Melotto is a professor in the Department of Plant Sciences working to understand how microscopic critters such as Salmonella and E. coli get into fresh produce and make people sick. She discussed her research to develop disease-resistant lettuce during a conference hosted by the United Nations’ Food and Agriculture Organization (FAO). The One Health in Agrifood Systems Forum was held in Sanya, in China’s Hainan province, and brought together more than 200 people from around the world to exchange knowledge, build new partnerships and identify practical pathways for translating science into action.

The goal of the meeting was to inform international efforts to create a framework that brings together agriculture, systems for food distribution, and policy. Supporters are aiming for, eventually, an international agreement guiding every country in sustainable food systems as the world’s population hit 8.3 billion people this year.

Melotto moderated a plenary session on “One Health Data for Evidence-Based Decision-Making.” Experts offered ideas and examples for using solid information from different sectors to guide public health and agricultural policies. The FAO is working toward an international consensus on how to transform raw data from different fields into targeted, life-saving actions through a structured process, according to event organizers.

For a plenary session on “Building One Health Islands and Villages,” Melotto discussed her work to build a stronger plant immune system in lettuce to ward off pathogens. In the United States alone, infected greens are the source of more than 9 percent of foodborne illnesses, sickening an estimated 2.3 million people and costing up to $5.3 billion yearly.

Melotto was a panelist at a third session, a high-level dialogue on “From Science to Action with the One Health Approach.”

The “one health” idea argues that “the health of people, animals, plants and ecosystems is fundamentally interconnected,” according to the United Nations. “As climate change, biodiversity loss, emerging and re-emerging diseases, antimicrobial resistance, food safety risks and environmental degradation place growing pressure on agrifood systems, countries are increasingly adopting integrated approaches that bring together expertise across sectors.”

$1.5M in funding from USDA

Melotto has been working in this area for decades, looking especially at how pathogens invade the leaves of greens. Her presentations were based on more recent research looking at the larger interaction of plants, soil, and the microorganisms that live there, together called the plant microbiome. The work recently received two awards of nearly $1.5 million from the National Institute of Food and Agriculture, part of the U.S. Department of Agriculture.

One aspect of this research focuses on how a plant's immune system influences the plant microbiome. Within the immune system, proteins called JAZ suppress plant immune responses and are found across many plant species. The Melotto team is using CRISPR gene-editing technology to engineer JAZ genes in lettuce, aiming to understand how JAZ proteins shape the plant’s environment. Using that information, the team seeks to devise strategies to create healthier and safer crops.

Managing the plant microbiome more effectively also could reduce the need for chemical fertilizers and pesticides. Melotto is working on this angle with Jorge Rodrigues, a professor in the UC Davis Department of Land, Air and Water Resources.

Rodrigues and Melotto have argued that the components of the microbiome together adapt to harsh, low-nutrient environments. This dynamic interaction helps plants survive stressful conditions and may offer solutions to improve crop production. Read their review of the research here, published in Trends in Microbiology in 2023.

Lettuce was chosen for this research because it's economically vital (grown on more than 264,000 acres in California and worth $3.5 billion annually) and a popular item in American diets. It's also a great model plant due to the extensive genetic resources developed at UC Davis, including advanced breeding programs, a reference genome for lettuce and CRISPR tools, making it ideal for studying plant-microbe relationships.

Related links

Richard Michelmore, a distinguished professor in the UC Davis Department of Plant Sciences, has done extensive research to understand lettuce genetics, disease resistance and breeding. Learn more here.

Read more about the Melotto lab’s research on lettuce here.

Learn more about the FAO’s One Health in Agrifood Systems Forum here.