HIGHER-PLANTS AND UV-B RADIATION - BALANCING DAMAGE, REPAIR AND ACCLIMATION

Although UV-B is a minor component of sunlight, it has a disproportion ately damaging effect on higher plants. Ultraviolet-sensitive targets include DNA, proteins and membranes, and these must be protected for n ormal growth and development. DNA repair and secondary metabolite accu mulation during exposure to UV-B have been characterized in considerab le detail, but little is known about the recovery of photosynthesis, i nduction of free-radical scavenging and morphogenic changes. A future challenge is to elucidate how UV-B-exposed plants balance damage, repa ir, acclimation and adaptation responses in a photobiologically dynami c environment.