title: Integration and scaling of UV-B radiation effects on plants: from DNA to leaf.
abstract: A process-based model integrating the effects of UV-B radiation through epidermis, cellular DNA, and its consequences to the leaf expansion was developed from key parameters in the published literature. Enhanced UV-B radiation-induced DNA damage significantly delayed cell division, resulting in significant reductions in leaf growth and development. Ambient UV-B radiation-induced DNA damage significantly reduced the leaf growth of species with high relative epidermal absorbance at longer wavelengths and average/low pyrimidine cyclobutane dimers (CPD) photorepair rates. Leaf expansion was highly dependent on the number of CPD present in the DNA, as a result of UV-B radiation dose, quantitative and qualitative absorptive properties of epidermal pigments, and repair mechanisms. Formation of pyrimidine-pyrimidone (6-4) photoproducts (6-4PP) has no effect on the leaf expansion. Repair mechanisms could not solely prevent the UV-B radiation interference with the cell division. Avoidance or effective shielding by increased or modified qualitative epidermal absorptance was required. Sustained increased UV-B radiation levels are more detrimental than short, high doses of UV-B radiation. The combination of low temperature and increased UV-B radiation was more significant in the level of UV-B radiation-induced damage than UV-B radiation alone. Slow-growing leaves were more affected by increased UV-B radiation than fast-growing leaves.
authors.affiliation: Department of Forest, Rangeland, and Fire Sciences, College of Natural Resources, University of Idaho 875 Perimeter Drive MS1133, Moscow, Idaho, 83844-1133.
authors.forename: Vasile Alexandru
authors.initials: VA
authors.lastname: Suchar
authors.affiliation: Department of Forest, Rangeland, and Fire Sciences, College of Natural Resources, University of Idaho 875 Perimeter Drive MS1133, Moscow, Idaho, 83844-1133.
authors.forename: Ronald
authors.initials: R
authors.lastname: Robberecht
keywords: DNA damage; UV-B radiation; ecological integration; feedbacks; leaf area; ozone depletion; phenolics