Petunia plant tolerance

Parmar, P.N., and Brearley, C.A., 1995, Metabolism of 3- and 4- phosphorylated phosphatidylinositols in stomatal guard cells of Commelina communis L. Plant J. 8 425033. Pennycooke, J.C., Jones, M.L., and Stushnoff, C., 2003, Down-regulating alpha-galactosidase enhances freezing tolerance in transgenic petunia. Plant Physiol. 133(2) 901-909. 

Hanson et reported an increased tolerance in petunia cultivars as they approach the flowering stage. This was true for both sensitive and tolerant cultivars, with the latter more strongly influenced. They suggested that bud development produced a diffusible substance that moved down the plant and acted as a protectant. 

Overproduction of EPSPS has been observed in several plant cell cultures tolerant to glyphosate (12, 13, 29). In the case of glyphosate-tolerant Corydalis cultures, Smart et al. demonstrated by 2 D-gel electrophoresis, the overproduction of other proteins besides EPSPS. Since the levels of activity of several shikimate pathway enzymes were unaltered in the tolerant cell line compared to the parent cell line, it was concluded that these amplified proteins may not be involved in aromatic amino acid biosynthesis. It is possible that the other proteins may not have a role in the tolerance mechanism. Alterations in protein profiles between glyphosate-sensitive and tolerant petunia cell lines have also been observed. With the glyphosate tolerant carrot cell line, in addition to overproduction of EPSPS, the levels of aromatic amino acids were found to be enhanced (29). Based on the results with plant cell cultures, it was therefore not clear if overproduction of EPSPS was sufficient to obtain glyphosate tolerance in plants. 

Since aromatic amino acid biosynthesis occurs in the chloroplast of plants, and the petunia EPSPS was demonstrated to contain the information for its translocation to the chloroplast, it was of interest to determine if delivery of the bacterial mutant enzyme to chloroplast of transgenic plants affected the level of tolerance to Roundup . A hybrid gene was synthesized containing... 

More recently, the petunia EPSPS gene has been demonstrated to confer Roundup tolerance in transgenic tomato plants. The transgenic tomato plants were tested under field conditions for their productivity and vigor. No significant differences were observed in crop productivity between transgenic and control tomato plants. This demonstrates that introduction and expression of genes into plants does not affect crop yield. 

Best known as genes conveying new properties are the EPSPS gene from the plant Petunia hybrida, which codes for tolerance to the herbicide Roundup Ready [this is found in the Roundup Ready soybean (RRS)], and the cry genes from Bacillus... 

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