Science Questions

Can Plants get Cancer? Sasha Zanjani

Chris -  Cancer in the context of a human has got a specialist disorder.  What we mean by cancer, our cells that have lost the ability to obey the normal signals that control and dictate how things grow and move and obey signals that tell them not to go to other places in the body and not to grow through boundaries of tissues and not to disobey ‘kill yourself’ signals.  Because every cell in the body is programmed to die unless it’s told otherwise.

Cancer cells ignore that signal and so, they are immortal as Richard Van Noorden was saying, and they also disobey all those normal regulatory signals that can spread to other bits of the body and cause secondary tumours.  And it’s usually those secondary tumours that cause problems.  Now, plants don’t have a disease like that.  They don’t get secondary spread through their system of disease which starts in one part of the plant and goes elsewhere, at least in the form of the cells from the plant itself.  But they can get localized growths, a cancer-like phenomenon and just like some human cancers which can be triggered by microorganisms, cervical cancer for example is caused by infection with a virus, human papilloma virus.  Also, gastric cancer in the stomach is caused by bacterial infection, Helicobacter pylori, is strongly associated with gastric cancers.

In plants, there is an environmental organism, it’s called Agrobacterium tumefaciens, this is a soil dwelling bacterium and it has something called a transposon.  This is a piece of genetic material which the bacterium injects into the plant’s own genetic material and that transposon carries genes which code for growth factors.  And it causes the plant cells to begin to grow out of control.  And the idea is to produce a big growth locally on the plant that then gives a home and provides protection to bacteria and that’s a Gall.  And it’s very, very common, it’s called Crown Gall disease when the plants actually have it, but it doesn’t spread predictly to other bits of the plant.  So there are some similarities between human cancers and animal cancers and plant tumours like Crown Gall disease, but it’s not the same disease.  There’s nothing systemic as far as I know that does the same thing but it’s a very good question.

October 2009