Tuber-specific cphA expression to enhance cyanophycin production in potatoes.
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 (cphA(Te)) from Thermosynechococcus elongatus BP-1, which is under the control of the tuber-specific class 1 promoter (B33). Tuber-specific cytosolic (pB33-cphA(Te)) as well as tuber-specific plastidic (pB33-PsbY-cphA(Te)) expression resulted in significant polymer accumulation solely in the tubers. In plants transformed with pB33-cphA(Te), 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-cphA(Te) 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-PsbY-cphA(Te) 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.
Hühns
Maja
M
Agrobiotechnology, University of Rostock, Rostock, Germany.
Neumann
Katrin
K
Hausmann
Tina
T
Klemke
Friederike
F
Lockau
Wolfgang
W
Kahmann
Uwe
U
Kopertekh
Lilya
L
Staiger
Dorothee
D
Pistorius
Elfriede K
EK
Reuther
Jens
J
Waldvogel
Eva
E
Wohlleben
Wolfgang
W
Effmert
Martin
M
Junghans
Holger
H
Neubauer
Katja
K
Kragl
Udo
U
Schmidt
Kerstin
K
Schmidtke
Jörg
J
Broer
Inge
I
D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D003600:Cytosol / Q000201:enzymology; D018506:Gene Expression Regulation, Plant; D010453:Peptide Synthases / Q000235:genetics* / Q000378:metabolism; D010940:Plant Proteins / Q000096:biosynthesis*; D035281:Plant Tubers / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D018087:Plastids / Q000201:enzymology; D011401:Promoter Regions, Genetic; D011198:Solanum tuberosum / Q000235:genetics / Q000378:metabolism*
D001426:Bacterial Proteins; D010940:Plant Proteins; C024250:cyanophycin; D010453:Peptide Synthases; C113257:cyanophycin synthase, bacteria