Credit: University of Nottingham
Possibly the perfect image for an article which discusses the roots.
Scientists from the University of Nottingham, England and Tohoku University, Japan have helped to solve a mystery that has fascinated scientists since Charles Darwin - how plant roots sense water and change direction to find it. In a world where water for agriculture is becoming a global challenge this could lead to improved crop varieties which are better at foraging for water.
Their research - 'Root hydrotropism is controlled via a cortex-specific growth mechanism' - sheds new light on which part of the root perceives a water signal, and which tissues then change their growth to make the root change direction. Their findings have been published in Nature Plants.
Phys.org: How thirsty roots go in search of water
Ed: they will shed new light on the roots. Oh, God, the poetry!
There are plants which send down tap roots which will drill to China until they find water. There are others with roots radiating every which way and don't you love how maple trees do that relatively close to the surface so they have a better chance of breaking the foundation of your house.
Regardless of the root style, the root ends still have to be able to locate the water at a fine level so how do they do it.
Maybe you deduce intuitively it must be the tip of the root which senses the water and shouts Eureka to the team.
Lead researcher, Dr Daniela Dietrich from the School of Biosciences at Nottingham, said: "Even when most of the root tip was removed by laser or scalpel, roots of the model plant Arabidopsis thaliana still responded to a water gradient in the medium they were growing on. This showed that hydrotropism - the way in which plant roots respond to moisture content of soil - depends on perception and response in the elongation zone, a rapidly growing area of the root just behind the tip."
- PO
There's the intuition shot all to hell but the Rockhouse starts getting interested because the process seems to get more intelligent ... in a plant.
They also wanted to understand if hydrotropism requires the response of a specific root tissue. The plant hormone Abscisic Acid (ABA) is key to the molecular signalling pathway for hydrotropism, as is a gene called MIZ1. By taking mutants in which key components of this signalling cascade for hydrotropism were missing, and then inducing the expression of those same key components in specific tissue layers only, the researchers were able to demonstrate that the cortex, the tissue layer directly below the epidermis, is where root growth changes in response to water perception.
- PO
The Rockhouse grows more admiring of the sophistication of the process.
Dr Daniela Dietrich, the study's lead researcher at the University of Nottingham, said: "We were surprised to see that in both cases, expression in the cortex was able to rescue the hydrotropism response. For the gravitropic response, which involves auxin, the epidermis is important, so it is quite interesting to see that these two environmental responses are controlled by different plant hormones, acting on different root tissues."
- PO
In other words, one part of the root determines the relationship relative to gravity so it keeps growing downward and hydrotropism is the tendency toward water which is controlled by a different part of the root.
The interest student is invited to pursue this further and it's strongly recommended as fresh water becomes a steadily scarcer commodity.
Root hydrotropism is controlled via a cortex-specific growth mechanism, Nature Plants (2017). DOI: 10.1038/nplants.2017.57
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