The cell lineage theory, which explains stomatal patterning in monocot leaves as a consequence of orderly divisions, was studied in Tradescantia. Data were collected to test the theory at three levels of organization: the individual stoma; stomata distributed in one dimension, in linear fashion along cell files; and stomata apportioned in two dimensions, across the length and breadth of the lea...

The stomata of plants regulate gas exchange and water transpiration in response to changing environmental conditions. New work reveals that stomata also have an important role in host defense. In this issue of Cell, Melotto et al. (2006) show that stomata close upon detection of potential microbial pathogens to prevent the infection of the leaf interior. Moreover, pathogenic bacteria have evolv...

In open places, plants are exposed to higher fluence rates of photosynthetically active radiation and to higher red to far-red ratios than under the shade of neighbor plants. High fluence rates are known to increase stomata density. Here we show that high, compared to low, red to far-red ratios also increase stomata density in Arabidopsis (Arabidopsis thaliana). High red to far-red ratios incre...

One strategy for plants to optimize stomatal function is to open and close their stomata quickly in response to environmental signals. It is generally assumed that small stomata can alter aperture faster than large stomata. We tested the hypothesis that species with small stomata close faster than species with larger stomata in response to darkness by comparing rate of stomatal closure across a...

A study of the results of the observations shows that there was a marked difference in the behavior of the stomata of plants grown with and without irrigation, and of the stomata of those grown with various amounts of irrigation. Stomata of non-irrigated plants opened but little, and only early in the morning, while the stomata of plants with a sufficient water supply were fully open throughout...

Stomata are pores that regulate the gas and water exchange between the environment and aboveground plant tissues, including hypocotyls, leaves, and stems. Here, we show that mutants of Arabidopsis thaliana LLM-domain B-GATA genes are defective in stomata formation in hypocotyls. Conversely, stomata formation is strongly promoted by overexpression of various LLM-domain B-class GATA genes, most s...

Stomata of growth chamber-grown Vicia faba leaves have an enhanced CO(2) response, measured as change in stomatal aperture, compared to stomata of greenhouse-grown leaves. Reciprocal transfer experiments showed that the stomatal response to CO(2) acclimated to the growing environment. Stomata of growth chamber-grown leaves transferred to a greenhouse lost their high CO(2) sensitivity within 2-3...

A diploid potato (Solanum tuberosum) mutant called droopy wilts easily. Excised leaves of the mutant lost weight, and hence water, more rapidly and had many more open stomata than leaves of a normal sibling. Further, the stomata of abnormal plants remained open in wilted leaves. When the stomata of the abnormal mutant were closed by a chemical spray, its excised leaves lost water no more rapidl...