경희대학교 식물기능유전체학 실험실

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AUTHOR

Youn Hyung Lee, Dong Seok Lee, Jong Min Lim, Joo Mi Yoon, Seong Hee Bhoo, Jong Seong Jeon and Tae Ryong Hahn (2006)

TITLE

Carbon Partitioning in Arabidopsis is Regulated by the Fructose 6-phosphate, 2-kinase/fructose 2,6-bisphosphatase Enzyme

JOURNAL

J Plant Biology 49(1):70-79

The Abstract Of The Paper

We wished to further elucidate the mechanisms underlying carbon partitioning in plants and established an experimental system to study this by generating transgenic Arabidopsis lines that over-express both the fructose 6-phosphate, 2-kinase (F6P,2-K) and fructose 2,6-bisphosphatase (F26BPase) domains. We additionally produced knockout transgenic plants for these domains via RNAi and T-DNA tagging. In F6P,2-K over-expressing transgenic Arabidopsis, F6P,2-K activity increased slightly and Fru-2,6-P2 levels were found to be elevated by 80%, compared with wild type (WT). In contrast, F26BPase activity was similar to WT in these transgenic plants. When the F26BPase domain was over-expressed, however, F26BPase activity was increased by 70% compared to WT, whereas F6P,2-K activity was reduced to 85% of WT levels. In knockout and RNAi mutant lines which showed reduced F6P,2-K and F26BPase activities, the Fru-2,6-P2 levels were found to be only between 3% to 7% of WT. In F6P,2-K over-expressing transgenic lines, the levels of starch, hexose and triose phosphates slightly increased, whilst the sucrose content was marginally reduced. In F26BPase over-expressing plants, however, the level of soluble sugars and hexose phosphates slightly increased, but starch and triose phosphate contents were reduced. Furthermore, the levels of soluble sugars increased, whereas the starch and hexose phosphate quantities decreased, in F2KP-KO mutants when compared with WT. Our present data thus reaffirm that Fru-2,6-P2 contributes to the regulation of photosynthetic carbon partitioning between starch and sucrose in Arabidopsis leaves by limiting sucrose synthesis.

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