Analysis of a chimeric class-I patatin-GUS gene in transgenic potato plants: High-level expression in tubers and sucrose-inducible expression in cultured leaf and stem explants
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Patatin is a family of lipid acyl hydrolases that accounts for 30 to 40% of the total soluble protein in potato (Solanum tuberosum L.) tubers. To examine the regulation of the patatin genes, we constructed a chimeric gene containing 2.5 kb of 5′ flanking sequence from the class I patatin genomic clone PS20 transcriptionally fused to β-glucuronidase (GUS) and introduced it into potato plants using an Agrobacterium tumefaciens Tiplasmid vector. While the chimeric gene was expressed at high levels in tubers and in stolons attached to developing tubers, it was not normally expressed in leaves, stems, roots, or in stolons before tuberizatization. However, the expression of the class I patatin-GUS construct was not “tuber-specific” since leaf and stem explants cultured on medium containing 300 to 400 mM sucrose showed GUS activity equal or greater than that of tubers. The sucrose induction of GUS activity in leaf and stem explants was accompanied by the accumulation of patatin protein and large amounts of starch, but not by the morphological changes that normally are associated with tuberization. In contrast, the GUS reporter gene under the control of the 35S promoter of cauliflower mosaic virus showed an essentially uniform pattern of expression in transgenic potato plants and was not induced by sucrose.
Key wordsβ-glucuronidase (GUS) [β-D-glucuronoside glucuronosohydrolase EC 188.8.131.52] patatin potato tuber Solanum tuberosum L. sucrose transgenic plants
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- 6.Cutter EG: Structure and development of the potato plant. In: Harris PM (ed) The Potato Crop: The Scientific Basis for Improvement, pp. 70–152. Chapman and Hall, London (1978).Google Scholar
- 7.Ewing EE: Cuttings as simplified models of the potato plant. In: Li PH (ed) Potato Physiology, pp. 153–207. Academic Press, Orlando (1985).Google Scholar
- 8.Ewing EE, Wareing PF: Heat stress and the tuberization stimulus. Am Potato J 58: 31–49 (1981).Google Scholar
- 9.Horsch RB, Fry JB, Hoffmann NL, Wallroth M, Eichholtz D, Rogers SB, Fraley RT: A simple and general method for transferring genes into plants. Science 227: 1229–1231 (1985).Google Scholar
- 11.Logemann J, Mayer JE, Schell J, Willmitzer L: Differential expression of genes in potato tubers after wounding. Proc Natl Acad Sci USA 85: 1136–1140 (1988).Google Scholar
- 13.Murashige T, Skoog F: A revised medium for rapid growth and bioassays with tobacco tissue cultures. Physiol Plant 15: 473–497 (1962).Google Scholar
- 14.Oparka KJ, Wright KM: Osmotic regulation of starch synthesis in potato tubers? Planta 174: 123–126 (1988).Google Scholar
- 15.Paiva EP, Lister RM, Park WD: Induction and accumulation of the major potato tuber protein, patatin. Plant Physiol 71: 161–168 (1983).Google Scholar
- 17.Racusen D: Occurrence of patatin during growth and storage of potato tubers. Can J Bot 61: 370–373 (1983).Google Scholar
- 18.Racusen D, Foote M: A major soluble glycoprotein of potato. J Food Biochem 4: 43–52 (1980).Google Scholar
- 20.Twell D, Ooms G: Differential and photomorphogenic regulation of a chimaeric class II patatin gene in transgenic potato. Nucleic Acids Res (in press).Google Scholar