NON-DAMAGING AND POSITIVE EFFECTS OF UV RADIATION ON HIGHER PLANTS - Environmental UV Radiation: Impact on Ecosystems and Human Health and Predictive Models - page 157

Figure 2 . UV action and response spectra for control of anthocyanin production. Solid circles = maize
( Zea mays L.) coleoptiles 35 ; open circles = broom sorghum ( Sorghum bicolor L.) against a
background of R radiation 41 ; solid squares = broom sorghum ( Sorghum bicolor L.) against a
background of R radiation 42 ; open squares = inhibition of phytochrome-induced anthocyanin
synthesis in mustard ( Sinapis alba L.) cotyledons 43 . To facilitate comparison, the data are normalised
to 100.
Although action spectroscopy is a useful tool in aiding the identification of
photoreceptors, caution is often needed in their interpretation. In broom sorghum
( Sorghum bicolor ), the complex photoreceptor interaction in controlling anthocyanin
synthesis is different again. In this species, UV-B, UV-A, B and R wavelengths induce
anthocyanin synthesis 41,42 . Subsequent irradiation with FR radiation nullifies all but the
UV-B response, thereby suggesting the use of alternative photoreceptors to control the
induction of the response. Action spectra for the induction of anthocyanin synthesis in
sorghum are shown in Fig. 2. The UV irradiation treatments, which themselves produce
Pfr, were carried out under a background of R light. However, a damaging response
could also be induced by UV radiation with the response increasing as the wavelength
was decreased 41 . An example of an action spectrum for a damage response in the context
of anthocyanin synthesis is that for the inhibition of P-induced anthocyanin synthesis in