Plant molecular breeding with the modified metabolic capacity of transitory starch for increase of biomass resources

植物有能力将光能转化为化学能，并通过利用化学能固定大气中的二氧化碳。有效利用光合作用对植物的生存至关重要。一般认为，光合作用能力与短暂淀粉的积累呈正相关。因此，加强短暂淀粉的代谢能力有望导致光合作用能力、生长量和生产力的提高。对植物淀粉生物合成的关键酶ADP-葡萄糖焦磷酸酶(AGPase)进行了变构性质的修饰。修饰变构AGPase的拟南芥植株表现出瞬时淀粉代谢能力的增加，从而促进了植株的生长。本研究的目的是为水稻生产改良提供基础数据。1.嗜热脂肪芽孢杆菌AGPase的表达对已知变构分子不敏感。本研究将嗜热脂肪芽孢杆菌AGPase基因(BsAGP)导入叶片AGPase同工酶缺失的拟南芥植物中。转基因植株的AGPase活性和瞬时淀粉水平仅恢复到与野生型植株相同的水平，表明BsAGP受植物中未知分子的调控。2.水稻AGPase亚基基因的器官特异性表达谱RT-PCR产物分析表明，6个水稻AGPase基因在几个器官中表达差异。3.水稻ADP-葡萄糖转运蛋白候选基因的表达模式RT-PCR产物分析表明，水稻ADP-葡萄糖转运蛋白候选基因的转录本主要积累在胚乳中。

Plants have the ability to convert light energy to chemical energy and to fix atmospheric carbon dioxide by using the chemical energy. It is very important in the survival of plants to utilize the photoassimilate efficiently. It is generally known that the photosynthetic capacity is positively correlated with the accumulation of transitory starch. Therefore, to reinforce the metabolic capacity of transitory starch is expected to lead elevation of the photosynthetic capacity, the growth and the productivity. We have employed the modification of allosteric properties of ADP-glucose pyrophosphorylase (AGPase), which is the key enzyme of plant starch biosynthesis. Arabidopsis plants with modified allosteric AGPase showed the increase of metabolic capacity of transitory starch and thereby the plant growth. The aim in this study was to obtain the basic data for the improvement of rice plant productivity.1.Expression of AGPase that is insensitive to known allosteric moleculesAGPase from Bacillus stearothermophillus is insensitive to known allosteric molecules. In this study, the gene for B.stearothermophillus AGPase (BsAGP) was introduced into Arabidopsis plants that is deficient in the leaf AGPase isoform. The AGPase activity and transitory starch levels in transgenic plants recovered only to the same levels as wild-type plants, indicating that BsAGP is regulated by unknown molecules in plants.2.Organ-specific expression profiles of the genes for rice AGPase subunitsAnalysis of RT-PCR products showed that 6 rice AGPase genes expressed differently in several organs. One of the 6 genes generated two transcripts by alteenative splicing, whose proteins located in different subcellular compartments, cytosol and amyloplasts.3.Expression pattern of the candidate gene for rice ADP-glucose transporterAnalysis of RT-PCR products indicated that the transcripts for the candidate of rice ADP-glucose transporter accumulates predominantly in endosperms.