Few pulses of light a day could boost zeaxanthin production in space plants (not pictured). (Photo : Reuters )

Gently rubbing plants can prevent them from falling ill, according to a new study.

Plants constantly deal with mechanical stress, which can be caused by rain, wind, animals or other plants. The study found that plants can even respond to mild mechanical stimulus, like that of a touch.

Some responses to touch are obvious, such as the touch-me-not plant (Mimosa pudica) that closes its leaflets when you touch them. Other plants might response by triggering defense mechanisms.

Researchers in the latest study found that gently rubbing leaves of thale cress plants (Arabidsopsis thaliana) between thumb and forefinger can activate defense mechanism in the plant, making it more resistant to Botrytis cinerea, the fungus that causes grey mold.

Closer analysis showed that touching the plant led to a flurry of events. It activated genes that are related with mechanical stress. Even the levels of reactive oxygen species increased when the plant was touched.

The outer layer of plant also became more permeable, most probably to help molecules related with immune response to pass through the surface.

Other research on the subject had found that different plants respond differently to human touch; some plants die, others benefit by increasing resistance while some just don't respond.

Previously, the study team had showed that wounding plants increases their resistance to common fungus. In this study, researchers found that even gentle rubbing might trigger the same kind of immune response.

"Wounding and rubbing exemplify how plants can react to a situation that in principle could cause them to become more vulnerable. Instead, they react to touch by deploying a carefully-orchestrated defence response, an evolutionary skill that that presumably boosts survival," according to a news release by Biomed Central.

The study is published in the journal BMC Plant Biology.

Previous research from University of Western Australia has shown that plants can respond to sounds and make clicking sounds to talk to other plants.