Expression of a Petunia inflata pectin methyl esterase in Solanum tuberosum L. enhances stem elongation and modifies cation distribution

Abstract

Transgenic potato (Solanum tuberosum L.) plants were constructed with a Petunia in¯ata-derived cDNA encoding a pectin methyl esterase (PME; EC 3.1.1.11) in sense orientation under the control of the cauli¯ower mosaic virus 35S promoter. The PME activity was elevated in leaves and tubers of the transgenic lines but slightly reduced in apical segments of stems from mature plants. Stem segments from the base of juvenile PME-overexpressing plants did not dier in PME activity from the control, whereas in apical parts PME was less active than in the wild-type. During the early stages of development stems of these trangenic plants elongated more rapidly than those of the wild-type. Further evidence that overexpression of a plant-derived PME has an impact on plant development is based on modi®cations of tuber yield, which was reduced in the transgenic lines. Cell walls from transgenic tubers showed signi®cant dierences in their cation-binding properties in comparison with the wildtype. In particular, cell walls displayed increased anity for sodium and calcium, while potassium binding was constant. Furthermore, the total ion content of transgenic potatoes was modi®ed. Indications of PMEmediated dierences in the distribution of ions in transgenic plants were also obtained by monitoring relaxations of the membrane potential of roots subsequent to changes in the ionic composition of the bathing solution. However, no eects on the chemical structure of pectin from tuber cell walls could be detected.

Cellulose Binding Protein from the Parasitic Nematode Heterodera schachtii Interacts with Arabidopsis Pectin Methylesterase: Cooperative Cell Wall Modification during Parasitism

“…Transgenic potato plants overexpressing pectin methylesterase were characterized by relatively rapid elongation at early stages of development (Pilling et al, 2000). The enlarged size of plants overexpressing CBP or PME3 may be attributable to this type of PME action.…”

Structural Basis for the Interaction between Pectin Methylesterase and a Specific Inhibitor Protein

“…By generating free carboxylic groups, PMEs also affect the wall pH and consequently influence the activity of a wide range of hydrolytic enzymes, including PMEs (Grignon and Sentenac, 1991;Denes et al, 2000;Goldberg et al, 2001). PMEs produced by plants take part in important physiological processes, such as microsporogenesis, pollen growth, seed germination, root development, polarity of leaf growth, stem elongation, fruit ripening, and loss of tissue integrity (Tieman and Handa, 1994;Wen et al, 1999;Micheli et al, 2000;Pilling et al, 2000;Micheli, 2001;Pilling et al, 2004). They have also been reported to play a role in response to fungal pathogens (Wietholter et al, 2003) and are required for the systemic spread of Tobacco mosaic virus through the plant (Dorokhov et al, 1999;Chen et al, 2000;Chen and Citovsky, 2003).…”

QUASIMODO1 Encodes a Putative Membrane-Bound Glycosyltransferase Required for Normal Pectin Synthesis and Cell Adhesion in Arabidopsis

“…Inhibition of the expression of a PME in pea roots resulted in reduced root elongation, altered cell morphology, and reduced separation of root cap cells (Wen et al, 1999). A reduction in PME activity was correlated with enhanced elongation in shoot apical tissues in potato (Pilling et al, 2000). Overexpression of a fungal endo-␤ -1,4-D -galactanase in the cell wall in potato tubers led to a Ͼ 70% loss of galactan side chains.…”