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Why Plants Panic When It Rains

When a raindrop splashes across a leaf, a protective mechanism starts to work within plants.

By: THURSD. | 02-01-2025 | 5 min read
How It Works Floral Education
Why Plants Panic When it Rains

Do plants panic when it rains? Well, somehow they do. And while they may not have similar emotions or the ability to panic the same way that humans or animals do, they exhibit a surprisingly complex response to rainfall that researchers have likened to 'panic'. This phenomenon is primarily driven by the need for plants to protect themselves from potential threats associated with rain, such as the spread of pathogens. It is, also, a response due to their ability to sense and adapt to environmental changes. Here's how.

Rain Triggers Chemical Signals in Plants

A study conducted by an international team of scientists involving the University of Western Australia's (UWA) School of Molecular Sciences, the ARC Centre of Excellence in Plant Energy Biology, and Lund University discovered that a plant's reaction to rain is close to one of panic.

 

Why Plants Panic When it Rains
Plants 'panic' when it rains in a phenomenon primarily driven by the need to protect themselves from potential threats associated with the rain.
Photo by Anastacia Lebedeva

 

The research, published in Proceedings of the National Academy of Sciences, revealed complex chemical signals are triggered when water lands on a plant to help it prepare for the dangers of rain. UWA Professor Harvey Millar said after spraying plants with water and observing the effect, the researchers noticed a chain reaction in the plant caused by a protein called Myc2.

Professor Harvey Millar:

"“When Myc2 is activated, thousands of genes spring into action preparing the plant’s defences. These warning signals travel from leaf to leaf and induce a range of protective effects. As to why plants would need to panic when it rains, strange as it sounds, rain is actually the leading cause of disease spreading between plants.”

 

Why Plants Panic When it Rains
Photo by kyraxys

 

Why Do Plants 'Panic'? Are There Protective Effects of Plants Panicking When It Rains?

While water is essential for photosynthesis and overall plant health, rain can also introduce various pathogens, including bacteria, viruses, and fungal spores. In fact, rain is identified as a leading cause of disease transmission among plants. Thus, Professor Millar explained that the warning chemical signals that cause plant panic travel from leaf to leaf and induce a range of protective effects.

This, according to him is because rain causes diseases to easily spread between plants. When a raindrop splashes across a leaf, tiny droplets of water ricochet in all directions. These droplets can contain bacteria, viruses, or fungal spores. A single droplet can spread these up to ten meters to surrounding plants.

 

Why Plants Panic When it Rains
Photo by chulmin1700

 

Evidence also suggests that when it rains, the same signals spreading across leaves are transmitted to nearby plants through the air. One of the chemicals—associated with plant panic—produced is a hormone called jasmonic acid that is used to send signals between plants, according to Professor Millar. If a plant’s neighbors have their defense mechanisms turned on, they are less likely to spread disease, so it is in their best interest for plants to spread the warning to their nearby plants. Essentially, the signaling system allows them to communicate their stress and alert nearby plants, which can then also prepare their defenses. This communal response helps reduce the likelihood of disease spread within plant populations

Professor Harvey Millar:

“When danger occurs, plants are not able to move out of the way so instead they rely on complex signaling systems to protect themselves.”

 

Plants Panic When it Rains
Photo by sandid

 

Professor Millar, also, reinforced the notion that it is clear that plants have an intriguing relationship with water; with rain being a major carrier of diseases but also—at the same time—being a vital component for a plant’s growth and survival.

The Research on Why Plants Panic When It Rains

The researchers used a spray bottle to simulate rain. They found that, after ten minutes, over 700 genes in the plants they studied reacted in a 'panic-like' manner and continued to do so for about 15 minutes. The response was rapid, even from just a single touch of water, these scientists said.

 

Why Plants Panic When it Rains
Photo by Mirco Hunziker

 

The response affected chemical reactions in the plants, such as their hormone balance and how they create proteins. Warning signals were sent from leaf to leaf in the plants, with the plants ultimately taking defensive measures against the water. Plants that received repeated waterings had stunted growth and delayed flowering.

Positive Effects of Rain on Plants

 

Why Plants Panic When it Rains

 

Negative Effects of Rain on Plants

 

 

So, What’s the Bottom Line?

Even though plants need water, research shows that they panic about getting wet and can communicate about this and other perceived dangers. So, they do actually react to changes in their environment. Rain can have both positive and negative effects on plants, depending on factors such as the amount of rainfall, duration, and other environmental conditions.

 

Header image by Bibhukalyan Acharya, feature image by sandid.

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