Analysis of the P1 promoter in response to UV-B radiation in allelic variants of high-altitude maize

Here, we studied the UV-B regulation of P1 in maize leaves of high altitude landraces, and we investigated how UV-B regulates P1binding to the CHS promoter in both low and high altitude lines. In addition, we analyzed whether the expansion in the P1 expression domain between these maize landraces and inbred lines is associated to changes in the molecular structure of the proximal promoter, distal enhancer and first intron of P1. Finally, using transient expression experiments in protoplasts from various maize genotypes, we investigated whether the different expression patterns of P1 in the high altitude landraces could be attributed to trans- or cis-acting elements.Together, our results demonstrate that, although differences in cis-acting elements exist between the different lines under study, the different patterns of P1 expression are largely a consequence of effects in trans.Plants, because of their sessile lifestyle, have evolved adaptations to live under diverse environmental variables, including solar radiation. Sunlight contains qualities of light that are essential for photosynthesis, and also provides informational signals that control plant growth and development. At least three different types of photoreceptor systems exist in plant cells, perceiving red/far-red (phytochromes), blue/UV-A (cryptochromes and phototropins), and there is at least one putative UV-B receptor (UVR8), which was recently identified [1].UV-B (280 to 315？nm) is part of the solar radiation, and therefore plants are inevitably exposed to UV-B. UV photons cause cellular damage by generating DNA photoproducts and through direct damage to proteins, lipids, and RNA [2-4]. Plant responses to UV-B damage include repair [5,6] and avoidance [7,8]. Solar UV-B radiation flux varies over time and location on earth. It is higher at increased elevation, because there is less air mass and greater atmospheric transparency to shorter wavelength radiation, although local climatic conditions, such as c