Brassica juncea is grown worldwide for use in oil and mustard production. It is able to spread in the environment and can be hybridized with related species; it is pollinated by insects. The plants naturally produce substances known as glucosinolates, which act as a defence against pests and are also known to be associated with health benefits.
Pairwise used CRISPR/Cas to intervene in the metabolism of the glucosinolates and knock out specific gene functions of an enzyme. As a result, the leaves are less pungent. However, this intervention is associated with a reduction in those compounds which are especially relevant for positive health effects and necessary for the plant defence mechanisms.
According to the 2022 publication, the process of genetic engineering resulted in unexpected genetic changes such as rearrangements and recombination of gene sequences.
The plants were deregulated by the U.S. Department of Agriculture (USDA) without detailed risk assessment, and there was no in-depth investigation of possible health effects or environmental risks. Effects relating to the cultivation of the plants were also not taken into account, e. g. a possibly greater need for pesticides due to the weakened defence mechanisms.
The company, Pairwise, which cooperates with Monsanto (Bayer), specialises in applications of New Genetic Engineering in plants. It has already filed nearly 200 patent applications and announced the introduction of New GE plants several times. The patent application for mustard greens is WO2021030738.
This example shows that the use of the CRISPR/Cas gene scissors enables profound changes even if no additional genes are inserted. As a result, New GE plants must be examined in detail before a judgment can be made about their safety. The present case also reveals the dubious nature of the goals pursued by companies using New Genetic Engineering techniques: similar to other NGT organisms already on the market, such as tomatoes with alleged blood pressure lowering effects or soy with altered oil content, there appears to be no real progress to be expected from introducing these plants. The leaves of GM mustard are almost certainly less beneficial to health than conventionally grown mustard. As with previous genetic engineering techniques, the biotech companies give the impression of wanting to market everything and anything that is technically feasible and promises profits.