Science1 publisher3 min readPublished
Defra rules Tropic's gene-edited non-browning banana is precision bred in England
Defra has ruled that Tropic Biosciences' non-browning banana, made with edits as small as one DNA letter in three gene copies, is precision bred. That puts it outside England's strict GM food rules, though sales still need a separate Food Standards Agency approval.
The Scientist · Science desk
What happened
- Tropic used CRISPR/Cas9 to target PPO1, the gene for one of the enzymes that turns cut banana flesh brown.
- Tests on leaves from the first edited plant, and sequencing of leaves from its clones, found no leftover DNA from the editing kit.
- ACRE, the government's scientific advisers, pressed Tropic for more detail on possible unintended edits and was satisfied with the answers.
- Tropic already has the go-ahead for the non-browning banana in Japan and Brazil.
Compiled by The ScientistSomething wrong?How this is made
Why it matters
- precedent Other developers taking gene-edited crops through England's process can expect ACRE to question them closely on unintended edits before it signs off.
- constraint The determination was made under rules that apply only in England, so it does not settle the banana's status anywhere else.
- decision Growers and buyers weighing the fruit have only Tropic's own estimate, that browning accounts for about 20 percent of banana yield losses, to judge its value by.
Tropic describes its change as "as little as a single letter of DNA" in each of three copies of the gene [3], and that covers most of the edit. Browning begins when peeling, bruising or slicing breaks the fruit's cells open. Enzymes then meet chemicals they are normally kept away from, along with oxygen from the air, and the reaction makes brown pigment [6]. When the cells repaired the cuts Cas9 made in PPO1, they left a one-letter insertion or deletion in each copy of the gene and a seven-letter deletion in one [7]. The notice says those changes should stop the banana from making a working PPO1 enzyme [7].
Defra's question was where the change came from. In the legal sense, a precision-bred plant is a gene-edited plant whose changes could have happened naturally or through ordinary breeding, with no DNA added from another species [16]. The company files a marketing notice with Defra, ACRE reviews it, and the Secretary of State decides [15]. Tropic put its editing kit into the banana cells only temporarily, so that the kit would not become part of the plant's DNA [9]. According to ACRE, Tropic also checked its guide RNAs against a banana genome sequence to look for edits in the wrong places [11].
The crop's biology helps here. Bananas like the Cavendish are grown from shoots and tissue culture, not seed, so every new plant is a copy of the last [14]. Whatever the first edited plant carried, its clones carry too. The notice reports that the edits held steady across several generations [14].
I'd read Defra's ruling as a finding about the genome, because the precision-bred test asks where a genetic change came from [16]. The thing it doesn't tell you is how much longer an edited slice stays yellow, or compared with what. Discover's account of the notice does not include a browning measurement. The Norwich company says the fruit stays firm and yellow after peeling and slicing [1]. The claim that it has the same taste and texture as the standard Cavendish is also Tropic's, as is its description of the fruit as the first new commercial variety in more than 75 years [18].
Sale in England now depends on the Food Standards Agency, which only considers applications that include Defra's confirmation [17]. Abroad, chief executive Gilad Gershon said in a press release that the go-ahead in Japan and Brazil was "a major step forward in bringing innovative, waste-reducing produce to consumers worldwide" [13].
The non-browning fruit is one of several Tropic products. The company has launched a banana that stays green 12 days longer, and it credits that fruit with cutting transport waste by up to 50 percent [20]. Next it plans a variety resistant to Panama disease. Tropic says the disease has reached more than 20 countries and is an existential threat to the $25 billion banana industry [21].
What to watch
- Whether the Food Standards Agency approves the banana as food in England, and how long its review takes after Defra's confirmation.
- Publication of measured browning data for the edited fruit against unedited Cavendish, from Tropic or an independent lab.
- Whether Tropic's planned Panama disease resistant variety is filed through the same precision-bred route in England.