Aphids are genetic engineers

They take the concept of “manipulation” to another level. Can an insect alter a plant’s genetic code to its advantage? Those aphids, yes. They belong to the genus Hormaphis. And they direct the growth of witch hazel trees to develop galls. The end? That serves as a refuge for them. Aphids are genetic engineers.

Noticeable bumps

They are known as Gallen or Cecidia. It is tumor-like structures that plants develop. They are induced by a wide variety of insects, nematodes, fungi or viruses. It is a defense mechanism in which the plant responds with abnormal growth of its tissues. Your attempt is to cover the area that has been damaged, infected, or parasitized by another organism. They can take on myriad shapes and sizes, from amorphous bumps to spikes.

Aphids are genetic engineers who modify plants to make them their shelters.
Aphids are genetic engineers who modify plants to make them their shelters.

David Stern works on the Janelia Research Campus of the Howard Hughes Medical Institute. He wonders: How does an organism from one kingdom take control of the genome of an organism from another kingdom? How do you rearrange it to make yourself a home? ‘ The study A novel family of secreted insect proteins associated with the development of plant bile develop it.

Certain genes are activated in the salivary glands of aphids of the genus Hormaphis. They seem to direct the formation of bile when insects deposit their saliva on plants. “I think they discovered a whole new universe,” says Patrick Abbot, an expert in molecular ecology. “There is a high likelihood that similar genes will be found in other insects,” he adds.

“It is an ancient challenge in botany to find out how to study gall formation,” continues Stern. A few years ago he made an instructive observation. Aphids Hormaphis cornu They produced galls in witch hazel, small flowering trees that abound on campus. A few aphids even on a single leaf Hormaphis They produced green galls. And in others these cecidia were red in color. The answer was obvious to a scientist. Stern wanted to know what made the difference.

Matches in genes

He sequenced the genomes of the aphids that produced green galls and those that produced red galls. There was a gene that varied between the two. It was a specific gene that was different from each other. The finding aroused her curiosity: The gene was not similar to any of the previously identified genes.

They extended their search to other aphids. Those that produced gills had genes similar to those that caused color changes. Stern’s team called this group “bicycle” genes.

The bile-producing aphids on witch hazel trees activate these genes. This is how they produce “bycicle proteins”. Insects secrete these proteins in plant cells. They reprogram the tissue of the leaves. They cause a bile to form in place of the tissue, which follows its normal growth pattern. “Aphids are genetic engineers. Who would say?

“After years of wondering what’s going on, it’s so gratifying to show something,” concludes Stern.

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