Tuber specific cphA expression to enhance cyanophycin production in potatoes

Autor: Hühns, M.; Neumann, K.; Hausmann, T.; Klemke, F.; Lockau, W.; Kahmann, U.; Kopertekh, L.; Staiger, D.; Pistorius, E.K.; Reuther, J.; Waldvogel, E.; Wohlleben, W.; Effmert, M.; Junghans, H.; Neubauer, K.; Kragl, U.; Schmidt, K.; Schmidtke, J.; Broer, I.
In:

Plant Biotechnology Journal

Auflage: 7
ISBN: ISSN: 1467-7644
Seite: 883 - 898
Jahr: 2009

Einordung:
Institut: Professur Agrobiotechnologie

Abstract:
The production of biodegradable polymers that can be used to substitute petrochemical
compounds in commercial products in transgenic plants is an important
challenge for plant biotechnology. Nevertheless, it is often accompanied by reduced
plant fitness. To decrease the phenotypic abnormalities of the sprout and to increase
polymer production, we restricted cyanophycin accumulation to the potato tubers by
using the cyanophycin synthetase gene (cphATe) from Thermosynechococcus elongatus
BP-1, which is under the control of the tuber-specific class 1 promoter (B33).
Tuber-specific cytosolic (pB33-cphATe) as well as tuber-specific plastidic (pB33-PsbYcphATe)
expression resulted in significant polymer accumulation solely in the tubers.
In plants transformed with pB33-cphATe, both cyanophycin synthetase and cyanophycin
were detected in the cytoplasm leading to an increase up to 2.3% cyanophycin
of dry weight and resulting in small and deformed tubers. In B33-PsbY-cphATe
tubers, cyanophycin synthetase and cyanophycin were exclusively found in amyloplasts
leading to a cyanophycin accumulation up to 7.5% of dry weight. These tubers
were normal in size, some clones showed reduced tuber yield and sometimes exhibited
brown sunken staining starting at tubers navel. During a storage period over of
32 weeks of one selected clone, the cyanophycin content was stable in B33-PsbYcphATe
tubers but the stress symptoms increased. However, all tubers were able to germinate. Nitrogen fertilization in the greenhouse led not to an increased cyanophycin yield, slightly reduced protein content, decreased starch content, and changes in the amounts of bound and free arginine and aspartate, as compared with control
tubers were observed.

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