As much as we love to do it, your plants not only notice your excessive touching, but they actually hate it.

Look, we might be anthropomorphising a bit (okay, a lot) here, but research has shown that stroking really does change the plants in a multitude of ways – and researchers have just discovered another response to our touching: changes to the mitochondria.

"The lightest touch from a human, animal, insect, or even plants touching each other in the wind, triggers a huge gene response in the plant," says senior researcher and plant geneticist Jim Whelan, from La Trobe University in Melbourne.

"Within 30 minutes of being touched, 10 percent of the plant's genome is altered."

"This involves a huge expenditure of energy which is taken away from plant growth. If the touching is repeated, then plant growth is reduced by up to 30 percent," he added.

Scientists believe that plants act this way at least partly to ward off biting insects, changing weather conditions, or overcrowding.

What we still don't know though is why plants have such an incredibly intense effect to touching – a mechanism that comes at a high energy cost - but the researchers think the response is at least partly due to the mitochondria.  

The mitochondria – AKA everyone's favourite 'powerhouse of the cell' – is the part of the cell that produces energy for the rest of the cell in both animals and plants.

And the researchers wanted to see how the mitochondria affects thigmomorphogenesis, a fancy word for the plants response to touching.

The researchers used the plant equivalent of a lab rat for this experiment, called thale cress (Arabidopsis thaliana). The team grew a bunch of plants, and at four weeks old began touching them with a soft paint brush every 12 hours for 36 hours.

When Arabidopsis is touched, it begins pumping out RNA transcripts to build more of a protein called OM66.

But when the team used mutagens on the plants that affected the mitochondria, this OM66 response was disrupted – which suggests the mitochondria were playing a crucial role.

"Twenty-five mutants targeting mitochondrial function or regulators revealed that all affected the touch transcriptome," the researchers write in their paper.

"Mutations of genes encoding mitochondrial proteins altered hormone concentrations. Mitochondrial function modulates touch-induced changes in gene expression directly through altered regulatory networks, and indirectly via altering hormonal levels."

So what does all that science speak mean for your poor coddled plants?

Well, it's not as bad as you might think – although this process does affect the plants in really intense ways, usually the plants survive regardless. Touch changes the plants, but it's not necessarily a bad change.

That being said, past research has shown that frequent touching, moving, or bending will create shorter, stockier plants rather than tall, slender ones.

And it's been shown that this response can actually cause a greater resistance to pests in some circumstances.

The next step for the researchers is seeing whether this same effect occurs in crop plants

"As we don't understand why plants display such a strong defence response to touch, if we are to breed less touch-sensitive varieties, we need to first understand what some of the consequences might be," said Whelan.

"For example, could touch-resistant plants be more susceptible to disease because a crucial defence mechanism has been removed?"

The research has been published in The Plant Journal