Submitted to: Proteomics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/8/2007
Publication Date: 5/8/2007
Citation: Xu, C., Sullivan, J.H., Garrett, W.M., Caperna, T.J., Natarajan, S.S. 2007. Impact of Solar Ultraviolet-B Radiation on the Proteome in Soybean Lines Differing in Flavonoid Contents. Proteomics. 69:38-48. Interpretive Summary: The amount of solar ultraviolet-B (UV-B) light reaching the Earth's surface has increased as a consequence of stratospheric ozone reduction. Increased UV-B light has caused significant stress to plants in terms of poor yield and harmful mutations. Many experiments have examined UV-B effects on plant growth and photosynthesis. Proteins are a main component of leaves and important in leaf function. However, there are not many studies focused on the effects of UV-B on protein accumulation, and most of them have only examined a single protein. In this study we investigated the effects of solar UV-B light on all major leaf proteins in two similar soybean varieties which contain different amounts of compounds called flavonoids that block the effect of UV-B light. This study showed that solar UV-B light altered protein accumulation in both types of soybean plants and that flavonoids can act as screening compounds to protect plants from ultraviolet light. This work showed that solar ultraviolet-A light might also cause changes in leaf protein of plants. The findings should be of interest to researchers who are investigating the UV-B effects on plant physiology and will be useful for breeders developing more UV resistant soybeans.
Technical Abstract: Two-dimensional polyacrylamide gel electrophoresis (2D PAGE) was used to systematically investigate the impact of solar ultraviolet-B (UV-B) radiation on the soybean leaf proteome. Two isolines of the Clark cultivar, the standard line with moderate levels of flavonoids and the magenta line with reduced flavonoids levels, were grown in the field with or without natural levels of UVB. The 12-day-old primary leaves were harvested for proteomic analysis. More than 300 protein spots were reproducibly resolved and detected on each gel. Statistical analysis showed that 67 protein spots were significantly (P < 0.05) regulated by solar UV-B. Many more spots were regulated by UV-B in the magenta line than in the standard line. Another 12 protein spots were not altered by UV-B but showed significantly (P < 0.05) different accumulations between these two lines, and for most of these spots the line-specific differences even occurred under UV-B exclusion, which may be due to the high level of solar ultraviolet-A. Most of these spots were identified by mass spectrometry. These proteins are quite diverse and involved in metabolism, energy, protein destination/storage, protein synthesis, disease/defence, transcription, and secondary metabolism categories. Therefore, ambient level of UV-B had impact on the protein accumulation, and the magenta line was more sensitive than the standard line.