Research and analysis

ACRE guidance: releasing precision bred plants into the environment in research and development trials

Published 27 February 2025

Applies to England

This is draft guidance. It is published for reference alongside the draft Genetic Technology (Precision Breeding) Regulations 2025.

A precision bred organism is defined as an organism produced by modern biotechnology that only contains genetic changes that could have arisen through traditional breeding practices. The use of plants in a field trial that do not meet the definitions of a precision bred organism as set out in the Genetic Technology (Precision Breeding) Act 2023 (‘the act’)  may constitute an unauthorised release of a Genetically Modified Organism (GMO). The growing of these plants in field trials will need to be authorised under the Genetically Modified Organisms (Deliberate Release) Regulations 2002 before they can be trialled. If unsure about the regulatory status of the plant you are intending to grow in a field trial, you should contact Defra at genetictechnologies@defra.gov.uk. 

Growing of precision bred plants in the environment

The Genetic Technology (Precision Breeding) Act 2023 establishes a mandatory notification system for releasing precision bred plants into the environment for research and development purposes. No formal confirmation of precision bred status from Defra is required to perform plant field trials. However, you must notify Defra that you intend to grow precision bred plants outside for research and development trials by submitting a ‘Release Notice’ to Defra’s Genetic Technology Policy and Regulation Team at genetictechnologies@defra.gov.uk at least 20 days before you intend to plant your field trial.

Precision bred plants used in trials that are only covered by a ‘Release Notice’ cannot be marketed. This means that plants and material derived from them cannot enter the food or animal feed chains, by design or inadvertently.

Marketing of precision bred plants

“Marketing” is defined in s5(3) of the act. Its meaning is wider than a financial transaction, for example, and includes ‘making available with or without consideration’

Developers intending to market a precision bred plant must receive precision bred confirmation by submitting a ‘Marketing Notice’ to Defra. Defra’s Secretary of State will make a decision whether to confirm the precision bred status of a plant following a recommendation from the Advisory Committee on Releases to the Environment (ACRE), who will provide advice based upon the information submitted in the ‘Marketing Notice’.

When to use a release notice or marketing notice

A ‘Release Notice’ is sufficient for field trials where notifiers can ensure that material does not enter the food or animal feed chain. Where notifiers are unable to ensure this, they should obtain precision bred confirmation from Defra by submitting a ‘Marketing Notice’.

Developers should also consider applying for a food and feed marketing authorisation from the Food Standards Agency (FSA). Defra encourages those carrying out trials on or close to land that is used for commercial cultivation, or large-scale multisite trials to gain precision bred confirmation and a food and feed marketing authorisation. Trials carried out in this way have a higher likelihood that plant material will enter the food or animal feed chain, which is not authorised by a ‘Release Notice’.

Preventing the unintentional release of a Genetically Modified Organism

It is important for notifiers to check that their plants only contain genetic sequences that could result from traditional breeding before they are used in field trials. These analyses should focus on confirming the absence or removal of transgenes. Whole genome sequencing is not necessarily required but developers must systematically analyse their plants to ensure transgene absence. For example, PCR and Southern blot analysis of DNA associated with vectors or intermediaries may be sufficient to ensure that transgenes are not present. Defra recommends referring to expert molecular diagnosticians when designing PCR primers and analysing the results obtained from PCR reactions. Notifiers should not proceed with field trials until they are confident that all transgenes have been removed.

Preventing material from a trial under a ‘Release Notice’ being marketed

Material from field trials performed under a ‘Release Notice’ can be retained for continued research use. Unless a ‘Marketing Notice’ and food and feed marketing authorisation are in place, the person with overall responsibility for the project, (identified on the ‘Release Notice’), must ensure that no material is marketed or allowed to enter the food or animal feed chain.

Precision bred plants field trial best practice

Field trials performed under a precision bred plant ‘Release Notice’, without precision bred confirmation, should follow due diligence to ensure that material does not enter the food and animal feed chain. In practice, trial sites should be managed to reduce the chances of precision bred plant material being transferred outside of the confines of the field trial or persisting at sites where commercial cultivation could take place in following seasons. Mechanisms for dispersal include cross-pollination with sexually compatible species and machinery movement.  Persistence at the site may occur in some species through seed or vegetative material. Information on best practices to reduce the spread of plant material can be found on the ACRE Advice Collections page, including species specific management practices for common UK crops. If further information is required, please contact Defra at genetictechnologies@defra.gov.uk

Specific management areas are covered in the following sections.

Isolation distances and pollen barriers

Notifiers should consider how isolated the location of the field trial is and whether there will be any sexually compatible crops growing nearby which flower in the same period.  This will determine the level of precautions that need to be taken to prevent cross-pollination and will vary between different plant species.  Precautions could include isolation distances and pollen barriers.

Crop specific guidance on isolation distances can be found in:

• APHA Seed Certification in England and Wales Technical Annex
• OECD Schemes for the Varietal Certification or the Control of Seed Moving in International Trade

Post-trial management

Some species can persist in the soil after a field trial is complete, as volunteers or groundkeepers. The length of time that these can persist varies between plant species. The management of the site can also affect how long reproductive material from some species can persist. For example, deep ploughing can enable oilseed rape seed to persist in the soil’s seedbank. Alternatively, shallow tilling, either post-harvest or early in the subsequent growing seasons can maintain seed near the soil surface where it can be encouraged to germinate and the resulting seedlings destroyed.

Post-trial monitoring for volunteers and groundkeepers is recommended along with management practices that minimise their occurrence, if the site is likely to be used for commercial production of the same crop in future seasons.  Any volunteers or groundkeepers should be removed and destroyed. Sexually compatible crops should not be grown on the field trial site until volunteer plants or groundkeepers have stopped appearing.  

Additional measures

Standard machinery cleaning practices should be carried out to remove and collect residual plant material on any machine used during the trialling process.  Measures should be taken to prevent wildlife from removing plant material from the field trial site, that are proportionate to the risk of this happening.

Emergency procedures

Emergency procedures should be in place for vandalism, trespass or other criminal acts, and possible remedial actions if the precision bred status is revised or not confirmed. Procedures should also be in place for extreme weather events or natural disasters that lead to the spread of plant material.

Glossary of terms

Marketing

The Environmental Protection Act 1990 (s.107, ss.11) (as amended), states that: “Genetically modified organisms of any description are “marketed” by a person when products consisting of or including such organisms are placed on the market by being made available to other persons, whether or not for consideration.”

PCR

Polymerase chain reaction. PCR is a lab technique to make many copies of a specific DNA region. It has many applications and is often used to detect the presence of transgenes when determining if something is a GMO.

Volunteer

A plant that grows on its own, rather than being deliberately planted by a farmer or gardener. 

Groundkeeper

An undesired plant arising from self-sown seed or from tubers in a planting of a desired species or variety.

Pollen barrier

Rows of traditionally bred plants that trap pollen from the precision bred plants during field trials.