Department of Plant Sciences, University of California Davis Davis, CA, USA.
Front Plant Sci. 2013 Dec 13;4:507. doi: 10.3389/fpls.2013.00507. eCollection 2013.
In order to study the role of PIP1 aquaporins in leaf water and CO2 transport, several lines of PIP1-deficient transgenic Populus tremula x alba were generated using a reverse genetic approach. These transgenic lines displayed no visible developmental or morphological phenotypes when grown under conditions of no water stress. Major photosynthetic parameters were also not affected by PIP1 down regulation. However, low levels of PIP1 expression resulted in greater leaf hydraulic resistance (an increase of 27%), which effectively implicated PIP1 role in water transport. Additionally, the expression level of PIP1 genes in the various transgenic lines was correlated with reductions in mesophyll conductance to CO2 (gm), suggesting that in poplar, these aquaporins influenced membrane permeability to CO2. Overall, although analysis showed that PIP1 genes contributed to the mass transfer of water and CO2 in poplar leaves, their down-regulation did not dramatically impair the physiological needs of this fast growing tree when cultivated under conditions of no stress.
为了研究 PIP1 水通道蛋白在叶片水分和 CO2 运输中的作用，我们利用反向遗传学方法生成了几种 PIP1 缺失的转基因欧洲山杨。在没有水分胁迫的条件下生长时，这些转基因系没有表现出明显的发育或形态表型。主要光合作用参数也不受 PIP1 下调的影响。然而，PIP1 表达水平的降低导致叶片水力阻力增加（增加了 27%），这有效地表明 PIP1 在水分运输中起作用。此外，各种转基因系中 PIP1 基因的表达水平与胞间 CO2 导度（gm）的降低相关，这表明在杨树中，这些水通道蛋白影响 CO2 通过膜的通透性。总的来说，尽管分析表明 PIP1 基因有助于杨树叶片中水分和 CO2 的传质，但在没有胁迫的条件下培养时，其下调并没有显著损害这种快速生长的树木的生理需求。
