Cell: Turn plants into zombies?

A newly discovered manipulation mechanism used by parasitic bacteria to slow down plant senescence may provide a new way to protect food crops threatened by disease
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Parasites manipulate the organisms they depend on to meet their needs, sometimes in extreme ways
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Under the magic of parasites, some plants have undergone tremendous changes, so that they are called "zombies": they stop reproducing and only serve as habitats and hosts for parasitic pathogens

So far, little is known about how this happens at the molecular and mechanistic level
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A study published in the journal Cell by the Hogenhout team of the John Innes Center and its collaborators found that a manipulator produced by phytoplasma hijacks the development of plants
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When inside plants, this protein causes key growth regulators to be broken down, triggering abnormal growth

Phytoplasma is a microorganism, notorious for its ability to reprogram the development of host plants
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This type of bacteria is usually the culprit of "ghost broom disease" in trees, where too many branches grow densely

Phytoplasma can also cause devastating crop diseases, such as aster verticillium wilt, which can cause severe yield reductions in cereals and leaf crops such as lettuce, carrots and cereals
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Professor Saskia Hogenhout, the corresponding author of the study, said: "The phytoplasma is a compelling example that shows that the scope of influence of genes can go beyond organisms and affect the surrounding environment
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"Our findings provide new clues to the molecular mechanisms behind this extended phenotype, which may help solve a major problem in food production
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We emphasized a promising strategy to achieve crops through engineering plants.

The new findings show how a bacterial protein called SAP05 uses the host's own molecular mechanisms to manipulate plants
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This molecule, called the proteasome, usually breaks down proteins that are no longer needed in plant cells
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SAP05 hijacks this process, causing plant proteins that play an important role in regulating growth and development to be effectively thrown into a molecular circulation center

Without these proteins, the development of plants will be reprogrammed, which is conducive to the growth of bacteria, which triggers the growth of multiple vegetative buds and tissues, and delays the senescence of plants
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Through genetic and biochemical experiments on the model plant Arabidopsis thaliana, the team revealed the role of SAP05 in detail
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Interestingly, SAP05 directly binds to plant developmental proteins and proteasomes
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Direct binding is a newly discovered method to degrade proteins

The plant developmental protein targeted by SAP05 is similar to the protein found in animals
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The research team would like to know whether SAP05 also affects insects that carry bacteria

However, this study allowed the research team to pinpoint the two amino acids required to interact with SAP05 in the proteasome unit
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Their research shows that if plant proteins are converted into the two amino acids found in insect proteins, they will no longer be degraded by SAP05, thereby preventing the abnormal growth of ghost broom disease

This discovery provides the possibility of adjusting only these two amino acids in crops, such as using gene editing technology to provide lasting resilience to the effects of phytoplasma and SAP05
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(Biocom)

Original search:

Parasitic modulation of host development by ubiquitin-independent protein degradation, https:// .
D OI: 10.
1016/j.
cell.
2021.
08.
029