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©KAUST 2023; Eliza Mkhitaryan

Sourcing a sustainable new vegetable oil

A long-term breeding program is developing elite lines of Salicornia to produce a sustainable and nutritionally valuable seed oil crop.

From saltwater lagoons in Venice and the South of France to inland lakes in the Arabian desert, Vanessa Melino and her team are gathering a remarkable and comprehensive collection of Salicornia germplasm.

The genus Salicornia includes annual species, commonly known as glasswort, samphire, sea asparagus or sea beans. The small, succulent herbs are obligate halophytes, meaning they require saltwater to grow — and these plants can even thrive in seawater, a trait not found in many plants.

When Melino joined KAUST in 2020, she inherited a small collection of Salicornia used for academic pursuits. She and Mark Tester, plant scientist and associate director of the Center for Desert Agriculture, recognized the potential to use genetic diversity to develop Salicornia as a high-value, sustainable seed oil crop.

“They require saltwater to grow, — and these plants can even thrive in seawater, a trait not found in many plants.”

“By focusing on the oil, we are trying to develop a product that can be transported easily and will replace other vegetable oils with something that is more sustainable — a plant that uses seawater instead of limited freshwater resources,” she says. Other breeding programs have focused on using the tender, young plant shoots as a salad vegetable — a perishable product, that is much more difficult to transport.

The goal is to have a plant that can be grown as part of an integrated system. “If you can integrate it with an aquaculture system, the effluent from fish farming can be used to fertilize the plants, and the crushed seed that is left after extracting the oil can be returned to feed the fish, making the system circular,” explains Melino.

While other Salicornia breeding programs exist, the KAUST team is the first to apply genetics and genomics to domesticate Salicornia, turning a wild plant into a crop, speeding up the steps to domestication to develop a high-value oilseed crop.

©KAUST 2023; Eliza Mkhitaryan

Another unique aspect of their breeding program is the introduction of genetic diversity to screen as many varieties as possible for seed oil quality traits, rather than focusing on large seed collections of one variety.

Their collection of annual and perennial species from around the world contains 267 genotypes, either collected from the wild or obtained from seed banks, including germplasm from the United States, Saudi Arabia, Italy, France and South Korea.

After two seasons of growing plants in the field at KAUST, two Saudi varieties are showing promise in terms of oil properties.

The program focuses on several attributes of the oil, including fatty acid composition, the presence of bitter compounds, known as saponins, and protein content.

The multidisciplinary team is also working with COMPOLYTICS, a small company that develops sensor technology, to develop a handheld scanner to assess seed quality and make it easier to integrate these properties into a breeding program.

“For health benefits we want a higher proportion of monounsaturated to polyunsaturated fatty acids, particularly a higher ratio of oleic acid to linoleic acid. The higher the ratio, the better the shelf life, and also the reported benefits for cardiovascular health,” says Melino.

“For health benefits we want a higher proportion of monounsaturated to polyunsaturated fatty acids, particularly a higher ratio of oleic acid to linoleic acid.”

Her team is also undertaking fundamental research to understand the mechanisms behind Salicornia’s uptake of sodium. Ph.D. student Octavio Salazar has identified a protein likely to be responsible for storing sodium in plant cell vacuoles. This is a first step toward understanding how the plant takes up and uses sodium in such large quantities.

Melino is also sequencing several species of Salicornia, developing five high-quality reference genomes, an important resource in any modern breeding program.

Looking to the future, she believes the best hope for growing Salicornia is coastal agriculture using integrated systems. “The other option, growing Salicornia around inland salt lakes or on salt-affected agricultural land, would take a lot more engineering solutions to ensure we don’t have a negative impact on the environment,” she says.