The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem; Rehovot, Israel.
Plant Signal Behav. 2012 Sep 1;7(9):1088-91. doi: 10.4161/psb.21162. Epub 2012 Aug 17.
Signs of abiotic toxicity often appear first at the margins of leaves and gradually spread toward the midrib. It has been suggested that the bundle sheath tissue surrounding the shoot vascular system acts as a solute transport-regulating barrier that prevents excessive quantities of toxic ions from entering the leaf and pushes them toward the hydathodes. We examined this hypothesis by examining the distribution of toxic boron (B) in mutant Arabidopsis leaves with flooded mesophyll and comparing it with that observed in control leaves that exuded guttation drops. As opposed to the control plants, which showed classical symptoms of B toxicity (necrosis starting at the leaf margins), in the mutants, necrosis was first observed inside the leaf. We will discuss this result and how it supports the hypothesis that the bundle sheath serves as a selective barrier filtering the xylem-to-leaf radial transport flow and pushing toxic solutes toward the hydathodes.
非生物毒性的迹象通常首先出现在叶片边缘，并逐渐向中脉扩展。有人提出，围绕着芽维管束系统的束鞘组织充当了一种溶质运输调节屏障，防止过多的有毒离子进入叶片，并将它们推向水孔。我们通过检查水淹型质体突变体拟南芥叶片中毒性硼（B）的分布，并将其与渗出吐水液滴的对照叶片进行比较，来检验这一假说。与表现出典型 B 毒性症状（从叶片边缘开始坏死）的对照植株不同，在突变体中，坏死首先出现在叶片内部。我们将讨论这一结果，以及它如何支持束鞘作为选择性屏障过滤木质部到叶片的径向运输流并将有毒溶质推向水孔的假说。
