C4Rice Centre, International Rice Research Institute (IRRI), Los Baños, Philippines.
Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, United Kingdom.
J Plant Physiol. 2021 May;260:153395. doi: 10.1016/j.jplph.2021.153395. Epub 2021 Feb 23.
We generated antisense constructs targeting two of the five Rubisco small subunit genes (OsRBCS2 and 4) which account for between 30-40 % of the RBCS transcript abundance in leaf blades. The constructs were driven by a maize phosphoenolpyruvate carboxylase (PEPC) promoter known to have enriched expression in mesophyll cells (MCs). In the resulting lines leaf, Rubisco protein content was reduced by between 30-50 % and CO assimilation rate was limited under photorespiratory and non-photorespiratory conditions. A relationship between Rubisco protein content and CO assimilation rate was found. This was associated with a significant reduction in dry biomass accumulation and grain yield of between 37-70%. In addition to serving as a resource for reducing Rubisco accumulation in a cell-preferential manner, these lines allow us to characterize gene function and isoform specific suppression on photosynthesis and growth. Our results suggest that the knockdown of multiple genes is required to completely reduce Rubisco accumulation in MCs.
我们构建了针对 5 个 Rubisco 小亚基基因（OsRBCS2 和 4）中的两个的反义构建体，这些基因占叶片中 RBCS 转录物丰度的 30-40%。这些构建体由玉米磷酸烯醇丙酮酸羧化酶（PEPC）启动子驱动，该启动子已知在叶肉细胞（MCs）中表达丰富。在产生的品系中，Rubisco 蛋白含量降低了 30-50%，并且在光呼吸和非光呼吸条件下 CO 同化率受到限制。发现 Rubisco 蛋白含量和 CO 同化率之间存在关系。这与干生物量积累和籽粒产量减少 37-70%显著相关。除了作为以细胞偏好方式减少 Rubisco 积累的资源外，这些系还允许我们对光合作用和生长的基因功能和同工型特异性抑制进行特征描述。我们的结果表明，需要敲低多个基因才能完全减少 MC 中的 Rubisco 积累。
