Manning Tahnee, Birch Rosemary, Stevenson Trevor, Nugent Gregory, Whitney Spencer
School of Science, RMIT University, Bundoora, VIC 3083, Australia.
Australian Research Council Centre of Excellence for Translational Photosynthesis, Research School of Biology, The Australian National University, 134 Linnaeus Way, Acton, ACT 0200, Australia.
PNAS Nexus. 2023 Jan 10;2(2):pgac305. doi: 10.1093/pnasnexus/pgac305. eCollection 2023 Feb.
The last decade has seen significant advances in the development of approaches for improving both the light harvesting and carbon fixation pathways of photosynthesis by nuclear transformation, many involving multigene synthetic biology approaches. As efforts to replicate these accomplishments from tobacco into crops gather momentum, similar diversification is needed in the range of transgenic options available, including capabilities to modify crop photosynthesis by chloroplast transformation. To address this need, here we describe the first transplastomic modification of photosynthesis in a crop by replacing the native Rubisco in potato with the faster, but lower CO-affinity and poorer CO/O specificity Rubisco from the bacterium . High level production of Rubisco in the potRr genotype (8 to 10 µmol catalytic sites m) allowed it to attain wild-type levels of productivity, including tuber yield, in air containing 0.5% (v/v) CO. Under controlled environment growth at 25°C and 350 µmol photons m PAR, the productivity and leaf biochemistry of wild-type potato at 0.06%, 0.5%, or 1.5% (v/v) CO and potRr at 0.5% or 1.5% (v/v) CO were largely indistinguishable. These findings suggest that increasing the scope for enhancing productivity gains in potato by improving photosynthate production will necessitate improvement to its sink-potential, consistent with current evidence productivity gains by eCO fertilization for this crop hit a ceiling around 560 to 600 ppm CO.
在过去十年中，通过核转化改善光合作用的光捕获和碳固定途径的方法取得了重大进展，其中许多涉及多基因合成生物学方法。随着将烟草中的这些成果复制到作物上的努力不断推进，现有的转基因选择范围也需要类似的多样化，包括通过叶绿体转化来修饰作物光合作用的能力。为满足这一需求，我们在此描述了对一种作物光合作用的首次叶绿体转基因修饰，即用来自细菌的速度更快但对CO亲和力较低且CO/O特异性较差的Rubisco替代马铃薯中的天然Rubisco。在potRr基因型中高水平生产Rubisco（8至10微摩尔催化位点/平方米），使其在含有0.5%（v/v）CO₂的空气中能够达到野生型的生产力水平，包括块茎产量。在25°C和350微摩尔光子/平方米光合有效辐射的受控环境生长条件下，野生型马铃薯在0.06%、0.5%或1.5%（v/v）CO₂以及potRr在0.5%或1.5%（v/v）CO₂条件下的生产力和叶片生物化学在很大程度上难以区分。这些发现表明，通过提高光合产物产量来增加马铃薯生产力提升的空间，将需要改善其库潜力，这与目前的证据一致，即对于这种作物，通过增施CO₂施肥提高生产力在CO₂浓度约为560至600 ppm时达到上限。
