Mak. Jansen et al., ULTRAVIOLET-B EFFECTS ON SPIRODELA-OLIGORRHIZA - INDUCTION OF DIFFERENT PROTECTION MECHANISMS, PLANT SCI, 115(2), 1996, pp. 217-223
Ultraviolet-B (UV-B) tolerance in plants has mostly been correlated wi
th the presence of screening pigments (e.g. flavonoids) or other reduc
tions in leaf transmittance. We have exploited the rapid turnover of t
he Photosystem II reaction center protein D1 as a sensitive in vivo pr
obe for UV-B damage. We found that the aquatic monocot, Spirodela olig
orrhiza, protects itself from UV-B irradiance using at least three dif
ferent mechanisms. In one case, protection is correlated to the presen
ce of UV-B screening pigments; in the second, an elevated oxygen-radic
al detoxifying system parallels UV-B tolerance; while in a third, UV-B
tolerance is related to a mechanism involving neither screening pigme
nts nor increased radical scavenging capacity. This demonstrates that,
in vivo, a plant can complement its UV-screening and attenuation stra
tegies by other tactics as well.