ISSN:
1399-3054
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
The role of fructose-2,6-bisphosphate (Fru-2,6-P2) in regulation of carbon metabolism was investigated in transgenic potato plants (Solanum tuberosum L. cv Dianella) transformed with a vector containing a cDNA-sequence encoding fructose-6-phosphate,2-kinase (F6P,2-K, EC 2.7.1.105)/fructose-2,6-bisphosphatase (F26BPase, EC 3.1.3.46) in sense or antisense direction behind a CaMV 35S promoter. The activity of F6P,2-K in leaves was reduced to 5% of wild-type (WT) activity, and the level of Fru-2,6-P2 was reduced both in leaves (10% of the WT level) and in tubers (40% of the WT level). Analysis of photosynthetic 14CO2 metabolism, showed that in plant lines with reduced Fru-2,6-P2 level the carbon partitioning in the leaves was changed in favour of sucrose biosynthesis, and the soluble sugars-to-starch labelling ratio was doubled. The levels of soluble sugars and hexose phosphates also increased in leaves of the transgenic plants. Most notably, the levels of hexoses were four- to six-fold increased in the transgenic plants. In tubers with reduced levels of Fru-2,6-P2 only minor effects on carbohydrate levels were observed. Furthermore, carbon assimilation in tuber discs supplied with [U-14C]-sucrose showed only a moderate increase in labelling of hexoses and a decreased labelling of starch. Similar results were obtained using [U-14C]-glucose. No differences in growth of the transgenic lines and the WT were observed. Our data provide evidences that Fru-2,6-P2 is an important factor in the regulation of photosynthetic carbon metabolism in potato leaves, whereas the direct influence of Fru-2,6-P2 on tuber metabolism was limited.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.0031-9317.2004.00318.x
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