Overriding the co-limiting import of carbon and energy into tuber amyloplasts increases the starch content and yield of transgenic potato plants.
Transgenic potato (Solanum tuberosum) plants simultaneously over-expressing a pea (Pisum sativum) glucose-6-phosphate/phosphate translocator (GPT) and an Arabidopsis thaliana adenylate translocator (NTT1) in tubers were generated. Double transformants exhibited an enhanced tuber yield of up to 19%, concomitant with an additional increased starch content of up to 28%, compared with control plants. The total starch content produced in tubers per plant was calculated to be increased by up to 44% in double transformants relative to the wild-type. Single over-expression of either gene had no effect on tuber starch content or tuber yield, suggesting that starch formation within amyloplasts is co-limited by the import of energy and the supply of carbon skeletons. As total adenosine diphosphate-glucose pyrophosphorylase and starch synthase activities remained unchanged in double transformants relative to the wild-type, they cannot account for the increased starch content found in tubers of double transformants. Rather, an optimized supply of amyloplasts with adenosine triphosphate and glucose-6-phosphate seems to favour increased starch synthesis, resulting in plants with increased starch content and yield of tubers.
Zhang
Lizhi
L
Botanical Institute, University of Cologne, Gyrhofstr. 15, D-50931 Cologne, Germany.
Häusler
Rainer E
RE
Greiten
Christian
C
Hajirezaei
Mohammad-Reza
MR
Haferkamp
Ilka
I
Neuhaus
H Ekkehard
HE
Flügge
Ulf-Ingo
UI
Ludewig
Frank
F
D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000688:Amylose / Q000378:metabolism; D001692:Biological Transport; D002244:Carbon / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D051599:Glucose-1-Phosphate Adenylyltransferase / Q000378:metabolism; D009004:Monosaccharide Transport Proteins / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D018087:Plastids / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011198:Solanum tuberosum / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism*; D013213:Starch / Q000737:chemistry / Q000378:metabolism*; D013214:Starch Synthase / Q000378:metabolism
D009004:Monosaccharide Transport Proteins; D010940:Plant Proteins; D012333:RNA, Messenger; D000244:Adenosine Diphosphate; D002244:Carbon; D000255:Adenosine Triphosphate; D013213:Starch; D000688:Amylose; D013214:Starch Synthase; D051599:Glucose-1-Phosphate Adenylyltransferase