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)这种增加可以减少铝在根尖中的积累，从而缓解铝的胁迫影响。为了产生根刺激的存在或不存在，玉米(Zea Mays L.)植物分别在有沙或无沙的情况下进行水培种植。沙地栽培的植株根尖上有大量的粘液，且每根尖的体积也比不沙地生长的大，说明刺激的存在可以促进粘液的产生。不同浓度的AlCl3在10Μm无沙土条件下才能发生铝伤害，但即使在1000Μm有沙土条件下也不能完全诱导铝伤害，说明有根刺激时铝毒害减轻。在有沙和无沙条件下采集的根尖，分成有粘液和不有粘液的根尖，然后在1000Μm的AlCl3溶液中暴露，有粘液的根尖铝积累量低于没有粘液的根尖，表明粘液对根尖具有保护作用。另一方面，去除粘液的叶尖与去除粘液的叶尖在铝的积累上没有显著差异。为了寻找原因，对去除粘液的尖端进行了监测，发现可见的粘液可以在5分钟内恢复。我们认为，粘液的快速恢复不会对粘液的去除产生显著影响。

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.