Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: July 1, 2000
Publication Date: N/A
Although UV-B is potentially harmful radiation, it is an important component of terrestrial radiation to which plants have been exposed since the land invasion. Plants have long been evolving mechanisms to avoid and repair UV radiation damage. So, it is not surprising that photomorphogenic UV-B responses are commonly assumed to be adaptations to harmful radiation. .This presupposes that the function of the observed responses is to prevent UV damage. It has been hypothesized that, as with Blue light, UV-B provides a signal important for normal plant development, and might be perceived within developing plants through non-destructive processes, perhaps through specific signal perception mechanisms. UV signal perception can lead to photomorphogenic responses which confer adaptive advantages under conditions associated with high light environments such as water stress. Plant responses to UV radiation in this regard include altered branching, leaf area, thickness, stomatal density, and increased chlorophyll production. Such responses led to altered transpiration rates and water use efficiencies. For example, we found that the effect of ambient UV-B radiation on stomatal density and conductance can lead to altered water use efficiencies as estimated by delta 13C stable isotope discrimination. In field settings, UV might more properly be viewed as a photomorphogenic signal than as a stressor. Hence, it might be insufficient to attempt to fully evaluate the adaptive roles of plant responses to UV-B cues upon stress tolerance by the simultaneous application of UV and drought or nutrient stress during development. We propose that rather than examine a plant's response to combinations of stressors, one might also examine how a plant's response to UV induces tolerance to subsequently applied stresses.