Poster: Oxidative Stress
Abs #
120: Molecular responses of maize to UV-B stress: gene expression profiling in irradiated and shielded tissues.
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Presenter: |
Casati, Paula , pcasati@stanford.edu |
Authors | Casati, Paula (A) Walbot, Virginia (A) | | Affiliations: |
(A): Stanford University
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Microarray hybridization to a Unigene array containing 5600 genes was used to assess UV-B responses in different tissues of a maize line deficient in flavonoid accumulation (b, pl mutant). Among 347 transcripts altered by at least 2-fold by UV-B, 285 were up-regulated in at least one of the organs examined while only 80 were down-regulated. We found that more transcript changes occur in tissues such as leaves exposed directly to UV-B than in shielded organs such as immature ears. A subset of transcripts up-regulated in leaves were down regulated in others, particularly in roots. Because shielded tissues such as roots, ears, and leaves covered with a plastic that absorbs UV-B, also showed changes in gene expression after plant exposure to UV-B, some signal(s) must be transmitted from exposed tissues to shielded organs. Adult tissues showed a larger number of transcripts affected by UV-B than younger tissues. Some genes were regulated by UV-B in more than one tissue, but most of the UV-B regulated genes were organ-specific. RNA blot hybridization was used to confirm selected transcript changes and to monitor the kinetics of UV-B –induced changes. Responses are rapid – detectable after 2 h exposure, both in exposed and shielded tissues. Supplemental UV-B increased expression of stress response and ribosomal protein genes, while photosynthesis-associated genes were down regulated as we previously reported in other experiments. The conclusions based on a smaller array of ~2500 genes in a previous report were confirmed and extended in the larger Unigene array; the data obtained through microarray experiment are consistent and reproducible. Supported by the National Science Foundation and by a postdoctoral fellowship to P. C. from Fundacion Antorchas.
