Plants evolved ability to actively control water-loss earlier than
previously thought

Date:
August 26, 2021
Source:
University of Birmingham
Summary:
New research has shed light on when plants first evolved the
ability to respond to changing humidity in the air around them,
and was probably a feature of a common ancestor of both flowering
plants and ferns.



FULL STORY ==========================================================================
New research has shed light on when plants first evolved the ability to
respond to changing humidity in the air around them, and was probably
a feature of a common ancestor of both flowering plants and ferns.


==========================================================================
Key to the regulation mechanism are tiny holes, or pores, on the surface
of leaves, called stomata. These enable the plant to regulate the uptake
of CO2 gas as fuel for photosynthesis, and the loss of water vapour -- a constant balancing act that requires the pores to open and close according
to changing conditions. This ability is important to agriculture because
it helps crops to use less water to grow.

Plants first evolved stomata soon after they moved from water to land,
some 450 million years ago, but scientists are still uncertain about
the evolutionary pathway they took and the point at which plants became
able to choose whether to open or close the pores in response to their environment.

In the most recently evolved plants -- flowering plants -- stomata
closure in response to drought is actively triggered by a number of
internal signals, including a hormone called abscisic acid (ABA), but scientists have been struggling to understand if this mechanism is also
present in older groups of plants. In a new study, published in Current Biology, researchers at the University of Birmingham have found evidence
that the fern species Ceratopteris richardii actively closes its stomata
using similar signals.

This semi-aquatic tropical fern has recently become the first model for exploring genetic control of development in the fern family, and is now
helping scientists to unpick the long evolutionary history between the
earliest land- living plants (mosses, liverworts and hornworts) and the
modern flowering plants that dominate today's ecosystems.

The team used RNA sequencing technology to identify the genetic mechanisms behind different stomatal responses and was able to demonstrate the fern's ability to close stomata in response to low humidity or in response
to ABA involves copies of genes already known to control stomata in
flowering plants.

The results suggest that both ferns and flowering plants evolved using
similar stomatal closure methods. This indicates that these mechanisms
were present - - at least in some form -- in the stomata of the last
common ancestor of both groups.

Dr Andrew Plackett, of the University of Birmingham's School of
Biosciences and Birmingham Institute of Forest Research, led the
research in collaboration with groups at the University of Bristol and the University of Oxford. He said: "We know that plants have possessed stomata
for most of their evolutionary history, but the point in evolution where
plants became able to actively open and close them has been controversial.

"We've been able to show the same active closure mechanisms found
in flowering plants are also present in ferns, a much older group of
plants. Being able to better understand how these mechanisms have changed during plant evolution gives us useful tools to learn more about how they
work. This will be important for helping our crops to adapt to future environmental changes." Alistair Hetherington from the University of
Bristol said: "This new work confirms that the earliest plants were
able to actively control the water they lost through the microscopic
valve like structures on the surfaces of leaves known as stomata. This
is important because it shows that the intracellular machinery
allowing stomata to open and close was present in the earliest land
plants. The research also shows that, whether stomata respond actively
or passively is dictated by the environment in which the plants lived." ========================================================================== Story Source: Materials provided by University_of_Birmingham. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Andrew R.G. Plackett, David M. Emms, Steven Kelly, Alistair M.

Hetherington, Jane A. Langdale. Conditional Stomatal Closure
in a Fern Shares Molecular Features with Flowering Plant Active
Stomatal Responses.

Current Biology, 2021 DOI: 10.1101/2021.03.06.434194 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/08/210826111639.htm

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