Tomato illustration

Model Organism: Garden Tomato (Solanum lycopersicum)

Phylum: Spermatophyta

Bred as a crop, the tomato is an ideal fruit model, related to peppers, eggplant, potatoes and more. Tomato's wild relatives are extreme adaptors to drought and pathogens. The tomato genome contains 900 million DNA base pairs.

Garden tomato: the search for the best plant traits

As the nation’s leader in agricultural production and exports, California provides one-third of the country’s vegetables and two-thirds of its fruits and nuts. But rising patterns of extreme weather are challenging food security.

Modern crop varieties are usually bred to a particular latitude and longitude as well as a particular climate pattern,” says Siobhan Brady, associate professor of plant biology. When these patterns change, it can negatively affect plant growth. Too little water, too much water, high temperatures, increased levels of carbon dioxide—these can all alter plant yield.”

The arid Andean Region of South America is home to one tough wild tomato species. Drought-, salt- and pathogen-tolerant, Solanum pennellii is an ideal study in extreme plant adaptations. Strong roots and waxy- skinned fruits and leaves help S. pennellii cope with desert challenges. UC Davis researchers are immersed in understanding S. pennelliis durability.

The root structure is an understudied area of the plant,” says Brady. Its below ground, but its responsible for bringing up all the water and nutrients to the above- ground part of the plant, which in turn is necessary for our nutrition.”

Brady studies S. pennellii and its domesticated relative Solanum lycopersium, the garden tomato. Unlike garden varieties, the desert tomatos roots continuously accumulate the compound suberin in its outer root layer, which enables water retention. The compound is only expressed in garden tomatoes during times of intense drought.

With cutting-edge genomics tools, Brady and her team seek the key to suberin production in the desert tomato. This data could help identify the mechanisms to introduce resilient root traits in other crops.

If it can be expanded to other crops by breeding for a particular factor that might increase its presence, then it could provide the garden tomatos roots with more waterproofing and a better ability to withstand drought,” says Brady.

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