Hello and welcome to another Fun Fact From Flora

Now today we are going to have a little look at a very cool species of bacterium called Agrobacterium tumefaciens which looks like this when attaching itself to a carrot cell.

This little guy is pretty cool and is actually a tumour-producing parasite. You might have seen some of the weird lumps it produces on plants.

The way that it does this is super cool. It has a little loop of DNA , called the Ti plasmid , which can essentially insert a section of itself into the genome of the plant host. It uses a syringe-like mechanism called a Type IV Secretion System to inject its DNA into the host.

Now there are a couple of genes that are whacked in.

Some are hormones, and more specifically growth hormones , that lead to the rapid formation of these tumours. One of those hormones is called auxin , which plants do make normally for themselves for growing, but this very rapid and concentrated production causes tumour formation.

And what’s pretty badass is that the DNA inserted uses a way of making auxin that the plant doesn’t normally use. This means that the plant has no way of regulating the auxin production. Normally plants are good at making sure they don’t grow tumours but this is a totally different pathway so they just can’t regulate it.

SUPER COOL.

The other badass thing that this bacterium does is that it inserts genes that code for enzymes.

These enzymes are able to make delicious nitrogen-filled compounds called opines. These molecules CANNOT BE METABOLISED BY PLANTS. So that bacterium has just tricked it into making a food source that ONLY IT CAN EAT.

They essentially reprogram the metabolic activity of the plant to make a compound that is totally useless to the plant itself and totally awesome for the bacterium.

Pretty epic if you ask me.

The other thing that’s very cool is we actually like to swap out the DNA that’s inside this bacterium to allow us to genetically engineer stuff. You take the DNA coding for auxin and opines out and put it in literally whatever you want and you have your own personal genetic engineer (in the form of A. tumefaciens ) that does all the hard work for you.

HOW NEAT IS THAT.

We love the science.

Love Flora xx