Wigoda Noa, Pasmanik-Chor Metsada, Yang Tianyuan, Yu Ling, Moshelion Menachem, Moran Nava
The R.H. Smith Institute of Plant Sciences and Genetics in Agriculture, The R.H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel.
Bioinformatics unit, G.S.W. Faculty of Life Sciences, Tel-Aviv University, Israel.
J Exp Bot. 2017 Jun 1;68(12):3179-3190. doi: 10.1093/jxb/erx067.
Under fluctuating ambient conditions, the ability of plants to maintain hydromineral homeostasis requires the tight control of long distance transport. This includes the control of radial transport within leaves, from veins to mesophyll. The bundle sheath is a structure that tightly wraps around leaf vasculature. It has been suggested to act as a selective barrier in the context of radial transport. This suggestion is based on recent physiological transport assays of bundle sheath cells (BSCs), as well as the anatomy of these cells.We hypothesized that the unique transport functionality of BSCs is apparent in their transcriptome. To test this, we compared the transcriptomes of individually hand-picked protoplasts of GFP-labeled BSCs and non-labeled mesophyll cells (MCs) from the leaves of Arabidopsis thaliana. Of the 90 genes differentially expressed between BSCs and MCs, 45% are membrane related and 20% transport related, a prominent example being the proton pump AHA2. Electrophysiological assays showed that the major AKT2-like membrane K+ conductances of BSCs and MCs had different voltage dependency ranges. Taken together, these differences may cause simultaneous but oppositely directed transmembrane K+ fluxes in BSCs and MCs, in otherwise similar conditions.
在波动的环境条件下，植物维持水分和矿物质稳态的能力需要对长距离运输进行严格控制。这包括控制叶片内从叶脉到叶肉的径向运输。维管束鞘是一种紧密包裹叶片维管系统的结构。有人认为它在径向运输过程中起到选择性屏障的作用。这一观点基于最近对维管束鞘细胞（BSCs）的生理运输分析以及这些细胞的解剖结构。我们假设BSCs独特的运输功能在其转录组中是明显的。为了验证这一点，我们比较了从拟南芥叶片中单独手工挑选的绿色荧光蛋白标记的BSCs原生质体和未标记的叶肉细胞（MCs）的转录组。在BSCs和MCs之间差异表达的90个基因中，45%与膜相关，20%与运输相关，一个突出的例子是质子泵AHA2。电生理分析表明，BSCs和MCs主要的类AKT2膜钾离子电导具有不同的电压依赖性范围。综上所述，在其他条件相似的情况下，这些差异可能导致BSCs和MCs中同时出现但方向相反的跨膜钾离子通量。
