Scientists from Julius-Maximilians-Universität Würzburg (JMU) in Bavaria,
Germany answered the puzzling question of why cereals are more drought
tolerant than other plants. Their answers, published in Current Biology,
could help develop crops with better drought resistance.

JMU plant researchers, Professor Rainer Hedrich, Professor Dietmar Geiger,
and Dr. Peter Ache found the answers through the mechanisms and components
of cereal plants' guard cells. According to them, grass cereals boast two
dumbbell-shaped guard cells that form and regulate the pore. Additionally,
they are flanked by two subsidiary cells, which absorb and store the
potassium and chloride from the guard cells when the pore closes. When the
stoma opens, they pass the ions back to the guard cells.

"Our cereals use the subsidiary cells as a dynamic reservoir for osmotically
active ions. This ion shuttle service between guard cell and subsidiary cell
allows the plant to regulate the pores particularly efficiently and
quickly," Prof. Geiger said.

Furthermore, they also found that aside from using abscisic acid (ABA) to
measure water availability, grass cereals also use nitrate to assess
photosynthetic performance. "By combining the two, the barley is better able
than other plants to negotiate between the extremes of 'dying of hunger' and
'dying of thirst' when facing water scarcity," Prof. Hedrich said.

[www.biozentrum.uni-wuerzburg.de]
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