SPEECHLESS, SCREAM and stomata development in plant leaves

phys.org | 11/15/2018 | Staff
magiccastlemagiccastle (Posted by) Level 4
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From left to right: Wild type stomata; SPEECHLESS (no stomata mutant); and SCREAM-D mutant (stomata-only leaf epidermis) in leaves of Arabidopsis (rockcress), a small flowering plant related to cabbage and mustard. Credit: Aarthi Putarjunan (U. Washington)/Keiko Torii (Nagoya University /U. Washington).

Plants constantly make trade-offs in their decisions: more light means more opportunity for photosynthesis, but then hot temperatures and dry air makes wilting more likely. Stomata—microscopic valves on the surface of a leaf's epidermis—are at the forefront of these trade-offs: stomata open to acquire fresh air (and the carbon dioxide in it) for photosynthesis, but water loss through stomatal pores causes plants to become dehydrated, and eventually to wilt.

Number - Distribution - Stomata - Leaves - Plant

The proper number and distribution of stomata on leaves is critical for plant productivity. Using the model plant Arabidopsis thaliana, a group of scientists including Keiko Torii (Howard Hughes Medical Institute/University of Washington and Institute of Transformative Biomolecules [ITbM] at Nagoya University), have identified key genes that make stomata and enforce proper stomatal patterning.

When a leaf starts to make epidermal cells, whether the initial cell becomes a stoma or non-stomatal epidermal cell is not yet decided. Differentiation of stomata starts when the master-regulatory proteins, SPEECHLESS and SCREAM, regulate gene expression. On the other hand, SPEECHLESS is inhibited by cellular signals involving MAP kinases MPK3 and MPK6, which transmit environmental signals to a cell. Depending on whether the master-regulatory proteins or the MAP kinases win, the initial cell becomes a stoma or non-stomatal epidermal cell. Nonetheless, the exact mechanism of how MPK3 and 6 inhibit SPEECHLESS was unclear until recently.

Paper - Nature - Plants - Dr - Aarthi

In the paper published in Nature Plants, Dr. Aarthi Putarjunan, Prof. Keiko Torii and...
(Excerpt) Read more at: phys.org
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