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What is Agrobacterium Tumefaciens?

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  • Written By: Mary McMahon
  • Edited By: O. Wallace
  • Last Modified Date: 29 October 2016
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Agrobacterium tumefaciens is a bacterium which is responsible for producing crown gall disease, a type of tumorous growth which can occur in many plants. This bacterium can be especially damaging for populations of grape vines, stone fruits, roses, beets, radishes, and nuts. Plants infected with the bacterium will produce distinctive galls, tumors which can grow quite large and which may be located at various regions on the plant. The gall can act to strangle the plant, depriving it of water and nutrients and causing it to become sickly.

This organism is gram negative and rod shaped, and it inhabits the soil in many regions of the world. It often congregates around the roots of plants, trees, and shrubs to take advantage of nutrients which may leak from the root system to sustain itself. As long as a plant remains healthy, Agrobacterium tumefaciens should not be a problem, as the surface layers of the roots will keep the bacteria out.

When a plant is injured, however, it allows the bacteria to enter, setting up an opportunity for the bacteria to colonize and cause crown gall disease. The bacteria themselves are actually not responsible; rather, the tumor is caused by a plasmid produced by the bacteria. This plasmid is known as a tumor inducing (Ti) plasmid, referencing the fact that it carries DNA which will cause tumors to develop. When bacteria are stripped of the Ti plasmid, they are still functional.

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For plants infected with Agrobacterium tumefaciens, there may not be much to be done. The plants can be pruned to remove the growth, and measures such as soil sterilization can also help. In some cases, it may be necessary to fully remove plants and their roots and to sterilize the soil to start from scratch. Since it can take several years to bring production up to previous levels, this measure is often avoided, if possible, to cut down on losses caused by infection.

Given that Agrobacterium tumefaciens works by introducing DNA into plants, it should come as no surprise to learn that this bacterium is used in genetic engineering. Researchers who want to introduce new DNA to a population of plants can engineer the plasmid, changing its contents so that it will deliver a payload of desirable DNA which it enters a vulnerable plant. Agrobacterium tumefaciens is used in labs all over the world which do work with transgenic crops, including labs which develop crops for commercial use, such as transgenic corn species.

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Perdido
Post 5

@Mykol – Crown gall is very ugly, isn't it? I recently dug up my five-year-old rose bushes to transplant them elsewhere in my yard, and I saw the tumorous growths at their base.

The mass looked like a big brown brain. It appeared that something monstrous had taken over my poor plant and was eating it slowly.

However, my local extension service told me that since the plant was a few years old and in good shape, it should be fine. I take care never to hoe around it, though, because one accidental swipe of the hoe could injure the base and let this bacteria into the rose bush.

seag47
Post 4

I am very interested in gardening, and I keep up with the different kinds of potential problems to look out for. I read an article about Agrobacterium tumefaciens that mentioned it was being studied to better understand cancer.

It seems that the way that Agrobacterium tumefaciens forms tumors is really similar to the way that cancer forms in animals and humans. So, studying crown gall can help educate researchers about cancer in other beings. It's great that something that is harmful by nature can be utilized for good.

myharley
Post 3

My brother has is own winery and grows grape vines for a living. When something like agrobacterium tumefaciens begins affecting your livelihood, this can be really serious.

Grape vines are extremely sensitive and it takes constant monitoring to make sure they remain healthy. A few years ago, many of the grape growers in our area had problems with crown gall disease.

It had a major affect on some of the big growers in our state. This business is a lot like farming as you have a lot at stake that you don't have any control over.

It is hard enough growing a good crop every year when you don't have any control over the weather conditions. When you have to fight these type of infections on top of the weather, it can be a constant battle.

Mykol
Post 2

I have a beautiful rose garden that I carefully tend to every year. I don't know how I could have prevented it, but one year most all of them became infected with crown gall disease.

I was devastated, as I had to cut all the roses back and hope for the best. I went to my local garden center for help on the best way to deal with this.

Roses can be temperamental and there is usually always something I am treating or spraying them for. Trying to get rid of the crown gall disease was one of the most difficult things I have treated them for.

LisaLou
Post 1

Radishes are one of my favorite vegetables I plant every year in my garden. One year they were infected with an agrobacterium strain and it completely ruined my whole crop.

Since I love to eat fresh radishes, I quickly set up a new garden spot. Radishes only take a few weeks to grow, so I was still able to get a fresh crop for the season.

The most frustrating thing was I had to till up a whole new garden space. I didn't want this to affect all the other vegetables I had planted.

Most of these take a lot longer to grow, so I didn't have as much produce for other vegetables that year. Since I already had other seeds planted, this was the best option at the time.

Since then, I have sterilized the soil in my old garden space, so now I have 2 spots where I can plant vegetables.

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