Showing papers by "Richard A. Jorgensen published in 1994"
TL;DR: A transgenic reporter system that monitors genomic impositions as changes in morphogenetically-determined flower color patterns is described, illustrating the proposals of Brink and McClintock that chromosomalImpositions occur during normal development as ordered sequences of events which contribute to the elaboration of complex developmental patterns.
Abstract: Developmental and physiological factors can impose heritable metastable changes on the plant genome, a fact that was established by maize geneticists during the 1950s and 1960s, largely through the efforts of R. Alexander Brink and Barbara McClintock. This paper describes a transgenic reporter system that monitors genomic impositions as changes in morphogenetically-determined flower color patterns. The observations reported here on the metastable properties of plant transgenes illustrate the proposals of Brink and McClintock that chromosomal impositions occur during normal development as ordered sequences of events which contribute to the elaboration of complex developmental patterns. The relationship between this process and some recent findings about the control of gene expression in transgenic plants is also discussed. © 1994 Wiley-Liss, Inc.
39 citations
TL;DR: Understanding the original mechanism for photocontrol of the chemical UV screen of land plants could be valuable for understanding the adaptability of extant land plants to rising levels of solar UV-B radiation and may suggest genetic strategies for engineering improved UV tolerance in crop plants.
Abstract: Most land plants possess the capacity to protect themselves from UV light, and do so by producing pigments that absorb efficiently in the UV-A and UV-B regions of the spectrum while allowing transmission of nearly all photosynthetically useful wavelengths.1,2 These UV-absorbing pigments are mainly phenylpropanoids and flavonoids. This chapter summarizes current understanding of the mechanism of UV protection in higher land plants, evaluates the information available from lower land plants and their green-algal relatives, and then considers the possible evolutionary origins of this use of chemical filters for selectively screening UV light from solar radiation. It is proposed that photocontrol over the biosynthesis of UV-absorbing phenylpropanoids and flavonoids may have evolved in concert with the evolution of the high biosynthetic activity necessary for UV protection. The toxicity of phenylpropanoids and flavonoids has been postulated to have been a barrier to the evolution of an effective chemical UV screen, and that some means for sequestering these compounds and/or for controlling their synthesis probably evolved prior to, or in concert with, the evolution of high rates of biosynthesis. The original photoreceptor and signal transduction system is speculated to have been based on photoisomerization of a phenylpropanoid ester and a pre-existing product feedback mechanism for controlling phenylpropanoid biosynthesis. Understanding the original mechanism for photocontrol of the chemical UV screen of land plants could be valuable for understanding the adaptability of extant land plants to rising levels of solar UV-B radiation and may suggest genetic strategies for engineering improved UV tolerance in crop plants.
10 citations