Zea mays Transcriptome or Gene expression. Zea mays

Microarray hybridization was used to assess UV-B responses in both directly exposed and shielded tissues of a maize line deficient in anthocyanin accumulation. Among 347 transcripts found to be regulated after 8 h of high UV-B irradiation, 285 were increased significantly in at least one organ but only 80 were down-regulated by UV-B. Although some genes were regulated by UV-B in more than one sample, most UV-B regulated genes were organ-specific. A larger number of transcript changes occurred in directly exposed than in shielded organs, and more transcripts levels were changed in adult than in seedling tissues. Because shielded tissues including roots, immature ears, and leaves covered with a plastic that absorbs UV-B exhibited altered transcriptome profiles after plant exposure to UV-B, some signal(s) must be transmitted from irradiated to shielded tissues. The time course of transcript abundance changes monitored by RNA blot hybridization and real time RT-PCR indicated that the response kinetics to UV-B are very rapid as some transcript levels are altered within 1 h exposure, in both exposed and shielded tissues. As the same total UV-B irradiation dose applied at three intensities elicited different transcript profiles, transcriptome changes do not show reciprocity. Confirming and extending prior microarray hybridization results, supplemental UV-B increased expression of stress response and ribosomal protein genes, while photosynthesis-associated genes were down regulated in adult leaves. Keywords: other