A biotechnological approach to increase carbon assimilation in C3-plants

在C3植物中，光呼吸始于1，5-二磷酸核酮糖羧化酶/加氧酶(Rubisco)活性部位的O2竞争抑制CO2固定，导致环境空气中固定的CO2至少损失25%。因此，光呼吸被认为是一种潜在浪费，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3-P来挽救乙醇酸2-P，从而重新进入C3还原循环。我们试图在模式植物拟南芥的叶绿体中引入两个交替的完整的乙醇酸分解代谢循环，以便直接释放和重新固定叶绿体中的CO2，从而通过增加CO2/O2比来降低Rubisco的加氧酶活性。因此，将建立一个自动调节循环，导致光呼吸途径的衰减，并预期二氧化碳同化效率的提高，从而更快地产生生物质。对含有完全运作的乙醇酸循环的转化子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.