Light and Stomatal Function: Blue Light Stimulates Swelling of Guard Cell Protoplasts

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Science  20 May 1977:
Vol. 196, Issue 4292, pp. 887-889
DOI: 10.1126/science.196.4292.887


Onion guard cell protoplasts swell when illuminated with blue light. The response is a 35 to 60 percent increase in volume and is dependent on potassium ion. Epidermal cell protoplasts do not swell under the same conditions. It is postulated that a membrane-bound blue photoreceptor mediates a direct response of guard cells to light.