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 76100, Israel.
Plant Cell Environ. 2012 Apr;35(4):735-46. doi: 10.1111/j.1365-3040.2011.02447.x. Epub 2011 Nov 29.
Tolerance to boron (B) is still not completely understood. We tested here the hypothesis that Thellungiella halophila, an Arabidopsis thaliana-related 'extremophile' plant, with abundance of B in its natural environment, is tolerant to B, and examined the potential mechanisms of this tolerance. With 1-10 mm B applied (B) to Thellungiella and Arabidopsis grown in hydroponics, the steady-state accumulated B concentration (B) in the root was below B, and was similar in both, suggesting both extrude B actively. Whether grown in soil or hydroponically, the shoot B was higher in Arabidopsis than in Thellungiella, suggesting more effective net B exclusion by Thellungiella root. Arabidopsis exhibited toxicity symptoms including reduced shoot fresh weight (FW), but Thellungiella was not affected, even at similar levels of shoot-accumulated B (about 10 to 40 mm B in 'shoot water'), suggesting additional B tolerance mechanism in Thellungiella shoot. At B = 5 mm, the summed shoot concentration of the potentially B-binding polyhydroxyl metabolites (malic acid, fructose, glucose, sucrose and citric acid) in Arabidopsis was below B , but in Thellungiella it was over twofold higher than B , and therefore likely to allow appreciable 1:2 boron-metabolite complexation in the shoot. This, we suggest, is an important component of Thellungiella B tolerance mechanism.
硼（B）耐性仍不完全清楚。我们在这里测试了一个假设，即 Thellungiella halophila 是一种与拟南芥相关的“极端环境”植物，其天然环境中硼含量丰富，对硼具有耐受性，并研究了这种耐受性的潜在机制。用 1-10mmB 施加于在水培中生长的 Thellungiella 和拟南芥，根中的稳态积累硼浓度（B）低于B，且两者相似，表明两者均主动排出 B。无论是在土壤中还是在水培中生长，拟南芥的地上部B均高于 Thellungiella，表明 Thellungiella 根系对 B 的净排斥作用更有效。拟南芥表现出毒性症状，包括地上部鲜重（FW）减少，但 Thellungiella 不受影响，即使地上部积累的B相似（“地上部水”中的约 10 至 40mmB），表明 Thellungiella 地上部具有额外的 B 耐性机制。在B = 5mm 时，拟南芥中潜在与 B 结合的多羟基代谢物（苹果酸、果糖、葡萄糖、蔗糖和柠檬酸）的总和地上部浓度低于B，但在 Thellungiella 中是B的两倍多，因此很可能在地上部允许相当数量的 1:2 硼-代谢物络合。我们认为，这是 Thellungiella B 耐性机制的重要组成部分。
