One of the key challenges the world faces is growing sufficient crops to feed the world. Researchers from the John Innes Centre at Norwich Research Park have made a discovery that could help to prevent crops from being hijacked by parasitic bacteria that can stunt their yields.

The research team have discovered how certain parasitic bacteria slow down the plant ageing process, and that it may offer new ways to protect disease-threatened food crops. Plant ageing is an important process as it enables crops to mature into edible fruit, seeds and vegetables.

Parasites typically manipulate the organisms they live off to suit their own needs, sometimes in quite dramatic ways. When under the control of a parasite, some plants undergo such extensive changes that they are described as ‘zombies’ because they just stop reproducing and serve only as a habitat and host for the parasite.

Until now, there’s been little understanding of how this happens but a research group led by Prof Saskia Hogenhout has identified a manipulation molecule produced by phytoplasma bacteria that hijacks plant development. When inside a plant, this protein causes key growth regulators to be destroyed, triggering abnormal growth.

Phytoplasma bacteria can cause devastating crop disease resulting in significant yield losses in grain and leaf crops.

The study showed how the protein produced by the phytoplasma bacteria manipulates plants by taking advantage of some of the host plant’s own molecular infrastructure that usually breaks down proteins no longer needed inside plant cells. The rogue bacterial protein hijacks this process, ejecting the plant proteins that are important in regulating growth and development.

Without these proteins, the plant’s development is reprogrammed in favour of the bacteria. Triggering the growth of multiple vegetative shoots and pausing the plant’s ageing process.

The proteins in the plants that are targeted by this hijacking bacteria are similar to proteins found in animals. That knowledge led the team to see if the rogue bacteria also affects the insects that carry it from plant to plant. They found that the structure of the host proteins in insects differed enough for them not to be affected.

The researchers were able to pinpoint two amino acids in the host plants that are needed for it to be affected by the damaging bacteria. They found that if the plant proteins were replaced by the two amino acids found in the insect protein, they become resistant to the bacteria.

This piece of work is important because it offers scientists the opportunity to use gene-editing techniques to adjust the two amino acids in crops so that they can become resistance to the effects of the parasitic bacteria.

Prof Hogenhout explained: “The findings of our study have cast a new light on a molecular mechanism that could help solve a major problem for food production. Our research has highlighted a way for engineering plants that will enable crops to achieve a greater resistance to potentially damaging bacteria and thus provide the potential to safeguard greater yields in the future.”