Can soil hardness alleviate aluminium stress in plant?

本研究旨在了解1)对根尖的物理刺激可以增加根尖粘液的产生，2)这种增加可以减少根尖上Al的积累，从而减轻Al的胁迫影响。为了创造对根系的刺激存在或不存在，玉米（Zea mays L.）植株分别在有沙或无沙的水培下生长。有沙生长的植物有大量的粘液根尖，而且每根尖的体积也比无沙生长的大，这表明刺激的存在可以促进粘液的产生。在不同浓度的alcl3下，Al损伤仅在10 Μm无砂条件下发生，但即使在1000 Μm有砂条件下也不能完全诱导，这表明在有根刺激的情况下Al毒性减轻。在有或没有沙子的条件下收集的根尖被分成有或没有粘液的两组，然后暴露在1000 Μm的AlCl3溶液中。有黏液的针尖比没有黏液的针尖积累的Al要少，说明黏液可以保护针尖免受Al的侵害。另一方面，有黏液的针尖与去除黏液的针尖在Al积累方面没有显著差异。为了寻找这一现象的原因，我们对去除粘液的针尖进行了监测，发现可见的粘液可以在5分钟内恢复。我们假定粘液如此迅速的恢复是粘液去除没有显著效果的原因。

This study was aimed to know 1) physical stimuli to root tips can increase production of root-tip mucilage, 2) such an increase can reduce Al-accumulation in the root tips, and consequently 3) stress impact of Al can be alleviated. To create the presence or absence of the stimuli to roots, maize (Zea mays L.) plants were hydroponically grown with or without sand, respectively. Plants grown with sand had numerous root tips with mucilage besides its volume per tip was also larger comparing to ones without sand, indicating that the presence of the stimuli can promote mucilage production. Giving AlCl3at various concentrations, Al injury could occur only at 10 Μm without sand but was not fully induced even at 1000 Μm with sand, revealing that Al toxicity is alleviated in the presence of the root stimuli. Root tips collected from conditions in the presence or absence of sand were divided into ones with or without mucilage, and then exposed to AlCl3 solution at 1000 Μm. The tips with mucilage showed lower Al -accumulation than ones without it, suggesting that mucilage could protect the tip against Al. On the other hand, there was no significant difference in Al-accumulation between the tips with mucilage and ones once removed it. To seek the reason for this, the tips once removed mucilage were monitored and found that visible mucilage could recover within 5 minutes. We have assumed that such a rapid recovery of mucilage is responsible for no significant effect of mucilage removal.