抄録
Cellular sugars have nonexclusive but crucial importance to plant cold hardiness. Three possible mechanisms contribute to sugar accumulation at low temperature: photosynthesis, starch/sugar conversion and sugar translocation. There is no doubt about the importance of photosynthesis. However, we recently showed genetically that starch/sugar conversion is also important for sugar accumulation during an early cold acclimation phase. Sugar translocation pathways are not fully elucidated in the apoplastic phloem loader Arabidopsis. We recently isolated an frt1 mutant that showed enhanced freezing tolerance in mature leaves, but not in young leaves, due to elevated sugar levels relative to the wild type. Accumulating evidence suggested a possible problem resides in sugar translocation pathways rather than sugar metabolism. Future prospects include a genetic screen for frt1-like mutants, which is promising in dissecting sugar translocation pathways. In addition, mutants with decreased sugar levels may provide a useful genetic background for evaluating non-sugar cryoprotective components.
