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Tissue Deposits for the US Plant Variety Protection Explained

In 2018, the US Farm Bill amended the US Plant Variety Protection Act, paving way for asexually reproduced plant varieties to be registered under the US Plant Variety Protection (PVP) system. Previously available for agricultural varieties only, the US PVP system requires a tissue deposit for title registration. While the deposit waiver passed by the USDA upon CIOPORA and AmericanHort’s request is still in force until January 6, 2023, CIOPORA reached out to Michael Lomas, Director at Bigelow’s NCMA and Center for Algal Innovation (Maine, USA) to learn more about the tissue deposits and related procedures.

Picture: Adobe Stock

CIOPORA (C): Michael, Bigelow is one of the three WIPO-approved International Depositary Authority (IDA) facilities in the United States and has also been approved to support the U.S. PVPO’s program for asexually reproduced plant varieties. Can you please explain how the plant material is processed at Bigelow Lab to create a tissue deposit for the US PVP applications?

Michael Lomas (ML): The first step in the process of creating a tissue deposit is filling out the required registration form so that the deposit authority knows how the depositor has identified the plant material, if there are any special considerations for long-term storage, and (most importantly) in what form the material will be shipped to the deposit authority. This may include cryopreserved tissue, callus tissue, plantlet with meristematic growth. This step will likely include one or more conversations between the deposit authority and depositors to make sure that material arrives correctly for processing. Once the registration form is approved, the material is shipped to the deposit authority.

Received materials are compared to the registration form to make sure all is in order, and if it is, a patent deposit number is provided, and the appropriate documentation is issued to the depositor. If plant tissue was shipped as cryopreserved tissue, it is immediately transferred to a long-term storage dewar, to await viability testing. If shipped as a plantlet, the meristematic tissue is excised, conditioned, and placed in a dewar for cryogenic storage while awaiting viability testing. To test for viability, cryopreserved tissue is slowly thawed, placed in recovery media for a defined period, and then stained with Evan’s Blue. Evan’s Blue stains ‘compromised’ tissue membranes, so if pieces of thawed plant tissue stain blue they will not grow back. If the tissue does not stain (will look greenish brown), it is viable and will ultimately grow back into a plant. We test six to ten individual pieces of plant tissue with the expectation that 50% of them will be viable. Once viability is tested, the viability documentation is completed and provided to the depositor. At this point, the deposit process is complete, and materials are stored for the duration of the protection.

C: Does the technology depend on species? Do labs specialize in certain plants?

ML: At a high level, the technology/procedural steps are the same across species within the same taxonomic family or related taxonomic families. Some species may recover better from cryopreservation with slightly different chemicals in the recovery media, but the chemicals are serving the same purpose – stimulation of growth.

Deposit authorities will generally specialize in different functional groups of plants, for example, seed propagated plants versus vegetatively propagated plants versus trees/shrubs based upon their expertise and infrastructure resources.

C: Is the plant material provided for the tissue deposit subject to public access during the duration of protection?

ML: Public access during the period of IP protection depends upon the specific IP regime pursued. Deposits made under the utility patent route become publicly available when a patent is issued. During the period of pendency, the material is not publicly available, but distribution can be requested by the depositor, a recognized Patent and Trademark Office (or equivalent), or a third party legally entitled.

If IP protection is being sought under the PVP Certificate, deposited tissue is not publicly available during the period of protection. There is a research-only exception during the period of protection, however, the depositor retains control over distribution requests. After protection has expired, access to material can be requested through the Germplasm Resource Information Network (GRIN).

C: What happens to the plant material after the IP right expires?

ML: Regardless of the IP protection regime, after the IP right expires, the holding facility contacts the original depositor and asks them if they would like any remaining material returned to them. If they do not want the material returned, then the material is destroyed. As most of the material will be cryopreserved pieces of plant tissue, in the case of storage at the NCMA deposit facility, the preferred method for destruction is thawing and subsequent autoclaving (121oC for ~1hour). This approach ensures that the material is no longer viable. All communication related to a deposit holding and its disposition is kept with the digital holding record. The digital holding record is archived but accessible, once the deposit is disposed of.


Useful links and downloads:

Bigelow NCMA Genetic Depository Overview
Download PDF • 2.19MB


Michael Lomas

Director, Bigelow’s NCMA and Center for Algal Innovation

Mike Lomas directs Bigelow’s National Center for Marine Algae and Microbiota (NCMA) and Center for Algal Innovation (CAI).

Bigelow CAI is a research and innovation center focused on growing the algal/microbial segment of the global bioeconomy. Bigelow’s NCMA is best known for housing the US national marine microalgae culture collection, holding ~3,000 algal strains, half of which are cryopreserved, and has a public mandate to curate and distribute microalgae for academic research and commercial applications. In addition to its collection, the NCMA also houses a genetic depository, approved by WIPO as an International Depositary Authority to accept algae, microbes, plant tissue, crop seed, and marine virus for patent purposes under Budapest Treaty. Mike received dual B.Sc. degrees in Marine Chemistry and Marine Biology from Long Island University – Southampton (now called Stony Brook at Southampton) and a Ph.D. in 1999 from the University of Maryland College Park. Learn more about Bigelow.


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