Guidance

Releasing precision bred plants into the environment

Published 13 November 2025

Applies to England

This guidance comes under the Genetic Technology (Precision Breeding) Act 2023 and the Genetic Technology (Precision Breeding) Regulations 2025.

You must follow this guidance if you plan to release precision bred plants into the environment for research and development purposes.  

You do not need to follow the guidance for research and development trials where you will not release the plant into the environment.  

If you plan to market the precision-bred plant, you must instead submit a ‘marketing notice’ to the Department for Environment Food and Rural Affairs (Defra).

Check the plant qualifies as precision bred 

Before release, you must make sure your plant meets the precision breeding criteria outlined in the ACRE guidance on producing precision bred plants.

If you release a plant produced by modern biotechnology that does not meet this criteria, it could be an unauthorised release of a genetically modified organism (GMO). You need separate authorisation to release a GMO.

You need to systematically analyse the plant to make sure it only contains genetic sequences that could result from traditional processes by either:

• confirming the absence of transgenes
• removing transgenes

You should not proceed with research and development trials until you are confident that there are no transgenes present.

Completing analysis

You can use DNA sequencing for individual genes, larger genetic regions, full chromosomes or entire genomes of any organism. DNA sequencing is the process of determining the nucleic acid sequence (the order of DNA bases – adenine, thymine, cytosine and guanine – within DNA).

You do not necessarily need to complete whole genome sequencing. For example, you might be able to use one of the following techniques to analyse DNA associated with vectors or intermediaries and confirm transgenes are not present:

• polymerase chain reaction (PCR) – a lab technique to make many copies of a specific DNA region, often used to detect transgenes
• Southern blotting – a technique used in molecular biology to detect specific DNA sequences in DNA samples

Defra recommends that you work with expert molecular diagnosticians when:

• designing PCR experiments
• designing suitable PCR primers
• analysing the results from PCR reactions

Notify Defra

You must submit a ‘release notice’ to Defra at least 20 calendar days before you intend to begin your trial.

This notifies Defra that you intend to grow a precision bred plant outside for research and development trials.

Keeping precision bred material out of food and feed chains  

You cannot ‘market’ a precision bred plant if it’s only covered by a release notice. This means you must make sure the plant and its material cannot enter the food or animal feed chains, by design or inadvertently.

If you cannot ensure this, you need to:

• submit a marketing notice and get confirmation of precision bred status from Defra
• get authorisation from the Food Standards Agency (FSA)

Keeping material for continued research

You can keep precision bred material from research and development trials performed under a release notice for continued research. However, you must continue to make sure that no material is marketed or allowed to enter the food or animal feed chain.

Conducting animal feeding trials

If you plan to conduct an animal feeding trial with material from a precision bred plant, you should discuss potential extra regulatory requirements with both:

• Defra at genetictechnologies@defra.gov.uk
• the Animal and Plant Health Agency (APHA) at customeradvice@apha.gov.uk

Follow field trial best practice

When completing field trials under a release notice, you should follow this best practice  to prevent precision-bred material from entering the food and animal feed chain.

You should manage trial sites to reduce the chance of precision bred plant material:

• transferring outside the boundaries of the field trial – for example, through movement of machines or cross-pollination with sexually compatible species
• persisting at sites where commercial cultivation could take place in following seasons – for example, through seed or vegetative material being left behind

Specific management techniques are covered in the following sections.

Isolation distances and pollen barriers

You should consider precautions such as isolation distances and pollen barriers to prevent cross-pollination.

Pollen barriers are rows of traditionally bred plants that trap pollen from the precision bred plants during field trials.

To determine the level of precaution you need, you should consider:

• how isolated the field trial is
• the plant species
• whether there will be any sexually compatible crops growing nearby that flower in the same period

Find crop-specific guidance on isolation distances 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

Preventing plants persisting post-trial

If the site is likely to be used for commercial production of the same or a sexually compatible species in future season, you should: 

• use management practices to minimise the occurrence of precision-bred plants persisting in the soil as ‘volunteers’ or ‘groundkeepers’
• complete post-trial monitoring for volunteers and groundkeepers
• remove and destroy any volunteers or groundkeepers
• not grow the same or sexually compatible species on the field trial site until volunteers and groundkeepers have stopped appearing

‘Volunteers’ are plants that grow on their own, rather than being deliberately planted by a farmer or gardener.

’Groundkeepers’ are undesired plants that grow from self-sown seed or planted tubers of a desired species or variety.

Plants can persist for different lengths of time depending on their species and the management of the site. For example:

• deep ploughing can enable oilseed rape seed to persist in the soil’s seedbank
• shallow tilling post-harvest or early in the next growing season can maintain seed near the soil surface – it can then be encouraged to germinate and the resulting seedlings destroyed

Cleaning machinery

You should carry out standard machinery cleaning practices to remove and collect residual plant material on any machine used during the trial.

Preventing spread through wildlife

You should take measures to prevent wildlife from removing plant material from the field trial site. They should be proportionate to the risk.

Emergency procedures

You should plan emergency procedures to apply in case of:

• vandalism, trespass or other criminal acts
• the precision bred status being revised or not confirmed – you should have remedial actions planned
• extreme weather events or natural disasters that lead to the spread of plant material

Other best practice advice

ACRE’s advisory reports for release of GMOs also cover best practice for reducing the spread of plant material, including species-specific management practices for common UK crops.

Get help

If you are unsure about the regulatory status of the plant you plan to grow in a research and development trial, contact Defra:

Email: genetictechnologies@defra.gov.uk