Faculty of Agriculture, Iwate University, 3-18-8 Ueda, Morioka, 020-8550, Japan.
Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe, 657-8501, Japan.
Photosynth Res. 2022 Aug;153(1-2):83-91. doi: 10.1007/s11120-022-00923-w. Epub 2022 May 30.
As chloroplast phosphoglycerate kinase (cpPGK) is one of the enzymes which has the highest capacity among the Calvin-Benson cycle enzymes, it has not been regarded as a determinant for photosynthetic capacity. However, it was reported that the rate of CO assimilation decreased under high irradiance and normal [CO] levels in the Arabidopsis cpPGK-knockdown mutant, implying that cpPGK has a control over photosynthetic capacity at a normal [CO] level. In the present study, the contribution of cpPGK to photosynthetic capacity was evaluated in transgenic rice plants with decreased amounts of cpPGK protein under high irradiance and various [CO] levels. The gene encoding cpPGK was suppressed using RNA interference techniques. Two lines of transgenic plants, Pi3 and Pi5, in which the amount of cpPGK protein decreased to 21% and 76% of that in wild-type plants, respectively, were obtained. However, there was no substantial difference in the rates of CO assimilation between wild-type and transgenic plants. The rates of CO assimilation decreased only slightly at elevated [CO] levels in the transgenic line Pi3 and did not differ between wild-type plants and the transgenic line Pi5, irrespective of [CO] level. These results clearly indicate that cpPGK does not have a strong control over photosynthetic capacity at various [CO] levels in rice.
由于叶绿体磷酸甘油酸激酶 (cpPGK) 是卡尔文-本森循环酶中活性最高的酶之一，它一直不被认为是光合作用能力的决定因素。然而，有报道称在高光强和正常 [CO] 水平下，拟南芥 cpPGK 敲低突变体的 CO 同化速率降低，这表明 cpPGK 在正常 [CO] 水平下对光合作用能力具有控制作用。在本研究中，在高光强和各种 [CO] 水平下，利用 RNA 干扰技术降低 cpPGK 蛋白含量的转基因水稻植株中，评估了 cpPGK 对光合作用能力的贡献。利用 RNA 干扰技术抑制编码 cpPGK 的基因。获得了两条转基因植株 Pi3 和 Pi5，其 cpPGK 蛋白含量分别降低到野生型植株的 21%和 76%。然而，野生型和转基因植株之间的 CO 同化速率没有实质性差异。在转基因系 Pi3 中，CO 同化速率仅在高 [CO] 水平下略有降低，而在 Pi5 转基因系中，无论 [CO] 水平如何，CO 同化速率均与野生型植株没有差异。这些结果清楚地表明，cpPGK 对水稻不同 [CO] 水平下的光合作用能力没有很强的控制作用。
