A biotechnological approach to increase carbon assimilation in C3-plants

光呼吸开始于O2在核酮糖1，5-二磷酸羧化酶/加氧酶（Rubisco）活性位点对CO2固定的竞争性抑制，并导致C3植物中环境空气中固定的CO2损失至少25%。因此，光呼吸被认为是一种潜在的浪费过程，限制了植物的生产力。C2-途径的主要功能是通过转化为甘油酸3-P来挽救乙醇酸2-P，甘油酸3-P重新进入C3-还原循环。我们试图引入两个替代的和完整的乙醇酸分解代谢循环到模式植物拟南芥的叶绿体中，以释放和重新固定的CO2直接在叶绿体内，从而降低Rubisco的加氧酶活性，通过增加CO2/O2的比例。因此，将产生自动调节循环，其导致光呼吸途径的衰减和CO2同化效率的预期改善，从而更快地产生生物质。对具有完全可操作的乙醇酸循环的转化体的分析也将产生数据，以补充我们对光呼吸途径的功能和调节及其与其他过程的相互作用的理解。

Photorespiration starts with the competitive inhibition of CO2 fixation by O2 at the active site of ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) and results in a loss of at least 25% of the CO2 fixed in ambient air in C3-plants. Thus, photorespiration was considered a potentially wastefull proces that was limiting plant productivity. The prime function of the C2-pathway is to salvage glycolate 2-P by conversion to glycerate 3-P, which re-enters the C3-reductive cycle. We attempt to introduce two alternative and complete glycolate catabolic cycles into chloroplasts of the model plant Arabidopsis thaliana in order to release and re-fix the CO2 directly within the chloroplast, thereby reducing the oxygenase activity of Rubisco by increasing the CO2/O2 ratio. Thus, an autoregulatory cycle would be created which results in an attenuation of the photorespiratory pathway and an expected improvement in the efficiency of CO2 assimilation and consequently, faster biomass production. Analyses of transformants harboring fully operational glycolate cycles will also generate data to complement our understanding of function and regulation of the photorespiratory pathway and its interaction with other processes.