Sudo Emi, Suzuki Yuji, Makino Amane
Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Aoba-ku, Sendai, 981-8555 Japan.
Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Aoba-ku, Sendai, 981-8555 Japan CREST, JST, Gobancho, Chiyoda-ku, Tokyo, 102-0076 Japan
Plant Cell Physiol. 2014 Nov;55(11):1905-11. doi: 10.1093/pcp/pcu119. Epub 2014 Sep 16.
Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) strongly limits photosynthesis at lower CO2 concentration [CO2] whereas [corrected] Rubisco limitation is cancelled by elevated [CO2]. Therefore, increase or reduction in Rubisco content by transformation with a sense or an antisense RBCS construct are expected to alter the biomass production under different CO2 levels. RBCS-sense (125% Rubisco of wild-type) and -antisense (35% Rubisco of wild-type) rice (Oryza sativa L.) plants were grown for 63 days at three different CO2 levels: low [CO2] (28 Pa), normal [CO2] (40 Pa) and elevated [CO2] (120 Pa). The biomass of RBCS-sense plants was 32% and 15% greater at low [CO2] and normal [CO2] than that of the wild-type plants, respectively, but did not differ at elevated [CO2]. Conversely, the biomass of RBCS-antisense plants was the smallest at low [CO2]. Thus, overproduction of Rubisco was effective for biomass production at low [CO2]. Greater biomass production at low [CO2] in RBCS-sense plants was caused by an increase in the net assimilation rate, and associated with an increase in the amount of N uptake. Furthermore, Rubisco overproduction in RBCS-sense plants was also promoted at low [CO2]. Although it seems that low [CO2]-growth additionally stimulates the effect of RBCS overexpression, such a phenomenon observed at low [CO2] was mediated through an increase in total leaf N content. Thus, the dependence of the growth improvement in RBCS-sense rice on growth [CO2] was closely related to the degree of Rubisco overproduction which was accompanied not only by leaf N content but also by whole plant N content.
1,5 - 二磷酸核酮糖羧化酶/加氧酶（Rubisco）在较低二氧化碳浓度[CO₂]下会强烈限制光合作用，而升高[CO₂]可消除Rubisco限制。因此，通过用正义或反义RBCS构建体转化来增加或减少Rubisco含量，有望改变不同二氧化碳水平下的生物量生产。将正义RBCS（野生型的125% Rubisco）和反义RBCS（野生型的35% Rubisco）水稻（Oryza sativa L.）植株在三种不同二氧化碳水平下培养63天：低[CO₂]（28 Pa）、正常[CO₂]（40 Pa）和升高[CO₂]（120 Pa）。在低[CO₂]和正常[CO₂]条件下，正义RBCS植株的生物量分别比野生型植株高32%和15%，但在升高[CO₂]条件下无差异。相反，反义RBCS植株的生物量在低[CO₂]时最小。因此，Rubisco的过量生产对低[CO₂]条件下的生物量生产有效。正义RBCS植株在低[CO₂]时生物量增加是由于净同化率提高，且与氮吸收量增加有关。此外，低[CO₂]时正义RBCS植株中Rubisco的过量生产也会增强。虽然低[CO₂]生长似乎额外刺激了RBCS过表达的效果，但在低[CO₂]时观察到的这种现象是通过总叶氮含量的增加介导的。因此，正义RBCS水稻生长改善对生长[CO₂]的依赖性与Rubisco过量生产的程度密切相关，这不仅伴随着叶片氮含量，还伴随着整株氮含量。
