Translation controls the expression level of a chimaeric reporter gene

Abstract

Transcriptional and translational fusions between the reading frame of the beta-D-glucuronidase gene (gusA) and the 2' as well as the 1' promoter of mannopine synthase (mas), a TR locus of Agrobacterium tumefaciens, were made. The expression of these constructs was studied in the transgenic F1 offspring of independent tobacco transformants at the protein level by assaying for GUS activity and western blot analysis of the GUS protein and at the steady-state mRNA level. In leaves, stems and roots no correlation was found between steady-state levels of GUS mRNA and enzyme activity. In older tissues significantly higher GUS activities were found. This is explained by the stable character of the GUS protein together with an accumulation of protein upon ageing. Three to ten times higher GUS activities were found for in vitro grown plants than for greenhouse-grown plants of the same offspring, despite similar levels of GUS mRNA. Roots from in vitro grown plants display three to ten times higher GUS activities than stems and leaves. In transgenic plants grown in vitro, containing a translational fusion with two AUGs in phase, the initiation of translation in leaf material occurred at both AUGs. Initiation of translation at the first AUG, however, was ten times more frequent. In contrast, initiation in roots from in vitro grown plants occurred exclusively at the second AUG.

Lhcb Transcription Is Coordinated with Cell Size and Chlorophyll Accumulation (Studies on Fluorescence-Activated, Cell-Sorter-Purified Single Cells from Wild-Type and immutans Arabidopsis thaliana)

“…This may not be true in all cases (e.g. Hensgens et al, 1992). In the present study we made 'the assumption that these parameters were similar in the green and white mesophyll cells of control and immutans leaves, and that they did not vary appreciably as a function of cell size.…”

Resistance to Protoporphyrinogen Oxidase-inhibiting Compound S23142 from Overproduction of Mitochondrial Protoporphyrinogen Oxidase by Gene Amplification in Photomixotrophic Tobacco Cells

“…For example, it has been shown that there was no correlation between the steady-state level of GUS mRNA and enzyme activity in transgenic plants. 28) In this case, the translation of GUS mRNA and the stability of the GUS protein played crucial roles in determining the ultimate level of GUS activity. Furthermore, the herbicide (glyphosate [N-(phosphonomethyl) glycine])-resistant cell culture of Corydalis semperviren had a 30-to 40-fold higher level of the herbicide target enzyme, 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), with a 10-fold enhanced level of the corresponding mRNA.…”

Root-preferential mRNA accumulation in Zea mays

“…The available evidence suggests that there are unique and overlapping sets of mRNAs among different plant organs (Kamalay and Goldberg, 1980;Kamalay and Goldberg, 1984). For the most part it is thought that a given population of mRNAs provides a template that is instrumental in determining the form and function of each cell in the plant body, however, if translational or post-translational regulation is important, this may not always be the case (Hensgens et al, 1992). The study of tissue-and cell-type preferential mRNA accumulation is a means to elucidate the genetic and molecular basis of plant development and function.…”