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- Title
Potato plants contain multiple forms of sucrose phosphate synthase, which differ in their tissue distributions, their levels during development, and their responses to low temperature.
- Authors
Reimholz, R.; Geiger, M.; Haake, V.; U. Deiting; Krause, K.-P.; Sonnewald, U.; Stitt, M.
- Abstract
Antibodies raised against a peptide fragment (residues 60-456) of potato sucrose phosphate synthase (SPS) were used to investigate whether potato plants contain multiple forms of SPS. When a partially purified preparation of SPS from cold-stored potato tubers was separated on 5% polyacrylamide gel electrophoresis (PAGE), four immunopositive bands were found with estimated molecular weights of 125, 127, 135 and 145 kDa. These bands were also found in rapidly prepared extracts and were termed SPS-1a, SPS-1b, SPS-2 and SPS-3, respectively. Direct evidence that SPS-1a and SPS-1b represent active SPS was provided by the finding that both are greatly reduced in plants expressing an antisense sequence derived from the potato leaf SPS gene. SPS-2 was not decreased in the antisense plants, indicating that it has a significantly different sequence. Evidence that SPS-2 represents active SPS was obtained by showing that the amount of SPS-1a and SPS-1b protein remaining in the leaves and tubers of antisense potato plants was too low to account for the remaining SPS activity. The four immunopositive SPS forms had different tissue distributions. SPS-1a was the major form in all tissues except petals, sepals and stamens. SPS-1b and SPS-2 were absent in very young growing tissues but were present as minorforms in source leaves and sprouting tubers. The SPS-1b level was especially high in petals and sepals, and the SPS-2 level was especially high in the stamens. SPS-3 was only detected in very young tissues.The four forms also showed different responses to low temperature. Transfer of tubers to 4 °C led to a specific and reversible increase of SPS-1b during the next 4 d. The appearance of SPS-1b correlated with a change in the kinetic properties of SPS that has recently beenshown (Hill et al 1996) to play a key role in triggering the accumulation of sugars in cold-stored tubers. The appearance of SPS-1b protein at low temperature was accompanied by an increase of SPS transcrip...
- Subjects
TISSUES; TUBERS; POLYACRYLAMIDE; SUGARS; ELECTROPHORESIS; GEL electrophoresis; COLLOIDS
- Publication
Plant, Cell & Environment, 1997, Vol 20, Issue 3, p291
- ISSN
0140-7791
- Publication type
Article
- DOI
10.1046/j.1365-3040.1997.d01-83.x