'Speechless' and 'Mute' help break the silence of the leaves

Jan 18, 2007
Stomata Development
The gene Speechless drives the division that initiates stomatal development. (Without Speechless, cells become the wax-coated, interlocking pavement cells on the surface of the plant, none of which open or close.) Two or three divisions after Speechless, Mute causes the formation of a guard mother cell. Then Fama causes the guard mother cell to divide into two equal guard cells that, as their name implies, guard the opening of the stomatal pore. Credit: University of Washington

Researchers have discovered two genes that guide land plants to develop microscopic pores that they can open and close as if each pore was a tiny mouth.

Plants wouldn't have been able to move from water to land 400 million years ago if they hadn't evolved this ability, which protects them from losing too much moisture.

The leaves and stems of land plants are dotted with the "tiny mouths," called stomata. When open, stomata allow the plant to take in carbon dioxide gas needed for photosynthesis and allow moisture to evaporate, pulling water from the roots into the plant. But when too much moisture is being lost, the two cells around the stomatal pore close it completely.

Without the genes guiding stomatal development, plants won't develop any mouthlike pores, hence the names Speechless and Mute for the newly discovered genes, according to Keiko Torii, a University of Washington associate professor of biology.

Two separate papers on the genes, one by Torii's UW group and the other by Stanford University researchers, have been published online by Nature, and are scheduled to appear in the print publication Feb. 1. Each group describes independently finding the gene that came to be called Speechless and its role in initiating the process that leads to stomata.

In addition, Torii's UW group published findings in its Nature article about another gene, one they named Mute, that triggers the key middle step that decides when a cell will fully become a stomata. Earlier this year the Stanford group published findings about the gene that controls the final step in stomata development, called Fama.

"In the last few months, we've gone from knowing surprisingly little about the genes involved to knowing all three major factors – Speechless, Mute and Fama," says Lynn Pillitteri, a research associate in biology and lead author of the Nature paper.

That the three are so closely related will be of interest to biologists studying both plants and animals, she says. Each is a basic protein with a helix-loop-helix domain, a sequence that is quite ancient and controls a vast range of physiological and developmental processes. Speechless, Mute and Fama also have very similar DNA sequences and could have arisen from a single gene that replicated and evolved, giving plants additional genes with slightly different characteristics.

Having two or three genes with similar characteristics would give plants what Torii terms "the freedom to play, to make functions that are the more elaborate stomata in modern plants."

Other biologists have seen something similar in animals. The ability to differentiate cells that become muscles also is controlled by consecutive action of basic helix-loop-helix proteins with DNA closely related to each other.

Molecular conservation of such key regulatory genes between plants and animals – genes that switch on and off cell-type differentiation programs from precursor stem cells – is intriguing and exciting, Torii says.

Source: University of Washington

Explore further: Sheep flock to Eiffel Tower as French farmers cry wolf

add to favorites email to friend print save as pdf

Related Stories

Staying warm: The hot gas in clusters of galaxies

18 minutes ago

Most galaxies lie in clusters, groupings of a few to many thousands of galaxies. Our Milky Way galaxy itself is a member of the "Local Group," a band of about fifty galaxies whose other large member is the ...

Gold rush an ecological disaster for Peruvian Amazon

18 minutes ago

A lush expanse of Amazon rainforest known as the "Mother of God" is steadily being destroyed in Peru, with the jungle giving way to mercury-filled tailing ponds used to extract the gold hidden underground.

New material makes water and oil roll off

22 minutes ago

Car finish, to which no dirt particles adhere, house fronts, from which graffiti paints roll off, and shoes that remain clean on muddy paths – the material "fluoropore" might make all this possible. Both ...

Recommended for you

How can we avoid kelp beds turning into barren grounds?

1 hour ago

Urchins are marine invertebrates that mould the biological richness of marine grounds. However, an excessive proliferation of urchins may also have severe ecological consequences on marine grounds as they ...

Genomes of malaria-carrying mosquitoes sequenced

17 hours ago

Nora Besansky, O'Hara Professor of Biological Sciences at the University of Notre Dame and a member of the University's Eck Institute for Global Health, has led an international team of scientists in sequencing ...

Bitter food but good medicine from cucumber genetics

17 hours ago

High-tech genomics and traditional Chinese medicine come together as researchers identify the genes responsible for the intense bitter taste of wild cucumbers. Taming this bitterness made cucumber, pumpkin ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.