Submitted to: Plant Molecular Biology International Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: March 31, 2000
Publication Date: N/A
Ultraviolet-B (UV-B) radiation negatively impacts the growth and development of plants. Tolerant plants alleviate these effects via UV-screening pigments that reduce penetration of UV-B into mesophyll tissue. Thus far, little is known about the relative contribution of specific phenolic compounds to the screening capacity of leaves. The D1 and D2 proteins constituting the photosystem II reaction center heterodimer are targets of UV-B radiation and can be used as an in situ sensor for UV penetration into photosynthetic tissue. Degradation of these proteins occurs under very low fluences of UV-B, and is strongly accelerated in the presence of an environmentally relevant background of visible light. Using the D1-D2 degradation assay, we characterized UV-B sensitivity of Arabidopsis mutants (tt4, tt5 and fah1) that are genetically altered in their composition of phenolic compounds. We found that changes in phenol metabolism result in altered rates of PSII reaction center heterodimer degradation under environmentally relevant mixtures of photo synthetically active radiation (PAR) and UV-B. Landsberg tt5 mutant showed increased UV-sensitivity with regard to D2 degradation relative to the Landsberg tt4 mutant and the WT.