Foundation Plant Services (FPS), established at the University of California, Davis in 1958 maintains virus-tested collections of grapes, fruit trees, roses, sweet potatoes, and strawberries. FPS provides many services to the global speciality crop industry, from import, quarantine, and therapy of grape and fruit tree material to the US, to research aimed at developing cutting edge diagnostics, and finally distribution of high-quality, virus-tested and true-to-type plant material.

Virus-tested grapevines make up FPS’s largest collection, with over 2,300 selections of more than 1,100 varieties. UC Davis Grape rootstock varieties GRN-1 and GRN-3, licensed by Global Plant Genetics, Ltd, are maintained at FPS and available for global shipping to licensees. FPS is also the source of propagative material for UC Davis strawberry varieties – if you have handled cultivars like, UCD Moxie, UCD Royal Royce, UCD Valiant, UCD Victor, UCD Warrior, UCD Finn, and UCD Mojo, they got their start in the tissue culture laboratory at FPS.

UC Davis’s five newest strawberry cultivars, UC Eclipse, UC Golden Gate, UC Keystone, UC Monarch, or UC Surfline, bred for resistance to Fusarium wilt, high yields, and improved fruit quality and released in 2023 have been available exclusively to California nurseries for the last two years, will be available January 2025 to global licensees.

The production of these strawberry varieties begins when the UC Davis strawberry breeding program transfers mother plants of advanced selections to FPS for virus testing and meristem tip culture therapy. “We have a really great working relationship with the program,” FPS Director Maher Al Rwahnih comments, “In advance of the decision to release material, the program requests that we produce clean plants so they are ready to distribute as soon as possible.”

FPS has worked closely with Global Plant Genetics for many years, and ships strawberry plantlets in vitro to customers around the world. The production of each of these plants begins in July, when the mothers are tested for viruses by grafting to virus indicator plants and direct HTS and PCR testing. These tests are required for the California Department of Food and Agriculture (CDFA) Strawberry Registration & Certification Program, as well as many international import permits. The mothers are then sent to heat treatment for three weeks at 37’ C, which will rejuvenate the material and act as therapy against viruses. Following heat treatment, meristems are excised and placed on tissue culture media. The excised meristem tissue will develop into a plantlet over the course of 4-6 months, with lab staff evaluating and transferring to new media every two weeks. FPS ships the finished plantlets in vitro to laboratories and nurseries who will transfer them to soil.

The expertise at FPS is not limited to production of tissue culture plants. Dr. Al Rwahnih leads a cutting-edge diagnostic research laboratory focused on improving molecular technology utilized when screening plant material. For decades, the gold standard of virus testing in horticultural crops like grape, strawberry, cherry, and rose was the use of biological indicators. These indicators are specific plant species or varieties that are known to display symptoms when exposed to certain disease agents. Research at FPS has led to the replacement of biological indicators in grape, cherry, and rose with high throughput sequencing (HTS). HTS provides an advantage because it gives a comprehensive picture of the entire microbial profile in a sample without prior knowledge of the pathogen. Many scientists have recognized the value of HTS, and there is a growing list of published research demonstrating its advantages over biological indicators. To replace biological indicators with HTS for regulatory testing requires thorough validation of diagnostic protocols after proving its advantages. Currently, FPS is engaged in strawberry and Rubus research comparing the efficacy of biological indicators to HTS. HTS is also employed in FPS’s current research conducting a survey of viruses present in California strawberry nurseries, commercial fields, and native stands. The goal of the survey is to identify the viruses present in the production system, to inform certification and quarantine program priorities, as well as nursery best management practices.

More information about Foundation Plant Services can be found at the program website, www.fps.ucdavis.edu.