About the Cover
On the Cover: Stomata play a key role in determining gas exchange in leaves. Consequently, understanding the physiology of stomata is critical to predicting the effects of environmental change on plant productivity. It has long been known that the chloroplasts of guard cells can perform electron transport; however, the difficulty of measuring photosynthetic activities of guard cells in planta has precluded the development of a sound understanding of the photosynthetic physiology of stomata. Lawson et al. (pp. 52-62) have used high-resolution imaging of chlorophyll fluorescence to measure photosynthetic activities of guard cells in intact leaves. The cover shows false color and grayscale (right inset) images of the quantum efficiency of photosystem II electron transport in the chloroplasts of the stomatal guard cells in a tradescantia leaf; the left inset shows the reflected light image of the stoma being studied. Photosynthetic electron transport rates in guard cells and their responses to O2 and CO2 were similar to those of adjacent mesophyll cells. This demonstrates significant Calvin cycle and Rubisco activity in guard cell chloroplasts.
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Copyright © 2007 by the American Society of Plant Biologists
