Kebeish Rashad, Niessen Markus, Thiruveedhi Krishnaveni, Bari Rafijul, Hirsch Heinz-Josef, Rosenkranz Ruben, Stäbler Norma, Schönfeld Barbara, Kreuzaler Fritz, Peterhänsel Christoph
RWTH Aachen, Institute of Biology I, Worringer Weg 1, 52056 Aachen, Germany.
Nat Biotechnol. 2007 May;25(5):593-9. doi: 10.1038/nbt1299. Epub 2007 Apr 15.
We introduced the Escherichia coli glycolate catabolic pathway into Arabidopsis thaliana chloroplasts to reduce the loss of fixed carbon and nitrogen that occurs in C(3) plants when phosphoglycolate, an inevitable by-product of photosynthesis, is recycled by photorespiration. Using step-wise nuclear transformation with five chloroplast-targeted bacterial genes encoding glycolate dehydrogenase, glyoxylate carboligase and tartronic semialdehyde reductase, we generated plants in which chloroplastic glycolate is converted directly to glycerate. This reduces, but does not eliminate, flux of photorespiratory metabolites through peroxisomes and mitochondria. Transgenic plants grew faster, produced more shoot and root biomass, and contained more soluble sugars, reflecting reduced photorespiration and enhanced photosynthesis that correlated with an increased chloroplastic CO(2) concentration in the vicinity of ribulose-1,5-bisphosphate carboxylase/oxygenase. These effects are evident after overexpression of the three subunits of glycolate dehydrogenase, but enhanced by introducing the complete bacterial glycolate catabolic pathway. Diverting chloroplastic glycolate from photorespiration may improve the productivity of crops with C(3) photosynthesis.
我们将大肠杆菌乙醇酸分解代谢途径引入拟南芥叶绿体中，以减少C3植物中固定碳和氮的损失，这种损失发生在光合作用不可避免的副产物磷酸乙醇酸通过光呼吸进行回收时。通过使用逐步核转化，利用五个编码乙醇酸脱氢酶、乙醛酸羧化酶和羟基丙二酸半醛还原酶的叶绿体靶向细菌基因，我们培育出了叶绿体乙醇酸直接转化为甘油酸的植物。这减少了但并未消除光呼吸代谢物通过过氧化物酶体和线粒体的通量。转基因植物生长更快，地上部和根部生物量更多，并且含有更多的可溶性糖，这反映出光呼吸减少和光合作用增强，这与1,5-二磷酸核酮糖羧化酶/加氧酶附近叶绿体二氧化碳浓度增加相关。在乙醇酸脱氢酶的三个亚基过表达后这些效应很明显，但通过引入完整的细菌乙醇酸分解代谢途径而得到增强。将叶绿体乙醇酸从光呼吸中转移出来可能会提高具有C3光合作用的作物的生产力。
