Gebbing Thomas
Grassland Science, Technische Universität München, 85350 Freising, Germany; Present address: Institute for Plant Production, University of Bonn, 53115 Bonn, Germany.
New Phytol. 2003 Jul;159(1):245-252. doi: 10.1046/j.1469-8137.2003.00799.x.
• Although fructan accumulation is reported in photosynthetically active organs, the long-term storage of fructan mainly occurs in more heterotrophic tissues. Significant amounts of fructan are stored in the internodes during grain filling of wheat (Triticum aestivum). The uppermost internode (peduncle) of wheat consists of a lower unexposed (i.e. enclosed by the flag leaf sheath and thus heterotrophic part, P ) and an upper exposed autotrophic part (P ). • Diurnal and long-term changes of fructan and sucrose (the precursor of fructan synthesis) contents were studied in P and P of potted wheat plants. • At mid grain-filling the sucrose concentration in P increased almost threefold during the light period and decreased in the following night. Diurnal changes in sucrose concentration were much less expressed in P . Fructan concentration was significantly higher in P than in P and did not change during the light period. • In another experiment, field grown wheat plants were sampled at regular intervals between 5 d before anthesis and grain maturity. At the time of maximum fructan content, 88% of the fructans in the total peduncle were stored in the heterotrophic P . Within P , fructan accumulation started in the older segments. The reason for the sharp separation of fructan storage between P and P remains unclear.
• 尽管据报道果聚糖在光合活性器官中积累，但果聚糖的长期储存主要发生在更多的异养组织中。在小麦（普通小麦）灌浆期，大量果聚糖储存在节间。小麦最上部的节间（穗轴）由下部未暴露的部分（即被旗叶鞘包围，因此是异养部分，P）和上部暴露的自养部分（P）组成。
• 研究了盆栽小麦植株P和P中果聚糖和蔗糖（果聚糖合成的前体）含量的昼夜变化和长期变化。
• 在灌浆中期，P中的蔗糖浓度在光照期增加了近三倍，在随后的夜晚下降。P中蔗糖浓度的昼夜变化不太明显。P中的果聚糖浓度显著高于P，并且在光照期没有变化。
• 在另一个实验中，在抽穗前5天到籽粒成熟期间定期对田间种植的小麦植株进行采样。在果聚糖含量最高时，穗轴中88%的果聚糖储存在异养的P中。在P内，果聚糖积累从较老的节段开始。P和P之间果聚糖储存明显分离的原因尚不清楚。
