Agriculture is the top user of the world's freshwater, and the increasing
population puts more pressure on this precious resource. For the first time,
scientists from the United States and United Kingdom have improved how a
crop uses water by 25 percent without compromising yield by altering the
expression of one gene that is found in all plants.

The research is part of the Realizing Increased Photosynthetic Efficiency
(RIPE), an international research project led by the University of Illinois.
The team led by RIPE Director Stephen Long increased the levels of a
photosynthetic protein (PsbS) to conserve water by tricking plants into
partially closing their stomata. When stomata are open, carbon dioxide
enters the plant to fuel photosynthesis, but water escapes through
transpiration. Carbon dioxide concentration in the atmosphere has increased
by 25 percent in the past 70 years, allowing plants to amass enough carbon
dioxide without fully opening their stomata.

Four factors trigger stomata to open and close: humidity, carbon dioxide
levels in the plant, the quality of light, and the quantity of light. This
study is the first report of hacking stomatal responses to the quantity of
light. PsbS is a key part of a signaling pathway in the plant that relays
information about the quantity of light. By increasing PsbS, the signal says
there is not enough light energy for the plant to photosynthesize, which
triggers the stomata to close since carbon dioxide is not needed to fuel
photosynthesis.

[www.igb.illinois.edu]
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