根表铁膜调控大叶相思耐强酸能力效应及其生理机制

As a serious soil pollution source, waste acid mine site is difficult for phytoremediation because most plants cannot survive in too strong acid soil when pH<2.5. Thus, screening and using strong acid tolerance plant species is the key for phytoremediation at waste acid mine site. We found that Acacia auriculiformis could survive in mine soil at pH 3.0 as well as nutrient solution at pH 2.0 with root nodules, which indicating that Acacia auriculiformis has enormous potential value in phytoremediation at waste acid mine site. More interestingly, its old roots were coated with red brown iron plaque when growing in quartz-sand with the nutrient solution under strong acid stress, and the numbers of iron plaque increased with decreasing of pH. However, reports about the relevance of root surface coating iron plaque and acid tolerance of host plant have not been found. This study was planned to investigate whether root surface iron plaque could help to improve acid tolerance of Acacia auriculiformis, and the physiological mechanisms in root surface iron plaque modulating acid tolerance of host plant. We are aim to provide new angle of view and theoretical basis for phytoremediation of waste acid mine.

强酸性废弃矿土不仅是严重污染源，且导致许多修复植物无法存活，给生态修复带来巨大阻力。因此选择利用耐强酸植物是强酸性废弃矿土修复的前提。前期研究中发现大叶相思可在酸性矿土（pH3.0）中及pH 2.0的基质中存活并结根瘤，表明其在强酸性矿土修复中具有重要价值；同时发现在极强酸（pH≤2.5）基质中大叶相思根表覆铁膜且铁膜成分含量随pH降低而增加。根表覆铁膜与植物耐强酸是否有相关关系目前还未见报道。基于此，本研究拟：通过根表有无铁膜的对比试验从个体生理活动以及植株表观形态等方面来阐明根表铁膜是否有助于提升大叶相思耐强酸能力；从渗透调节、抗氧化防御系统调控、激素调节、以及根系分泌有机酸等方面揭示根表铁膜调控大叶相思耐极强酸能力的生理机制。本研究结果将为强酸性矿土修复提供新的研究思路和科学依据，并为酸性土壤改良提供参考，同时有助于提高植物耐酸机理研究的理论深度和广度。

通过对比研究根表有无铁膜的大叶相思植株在强酸胁迫下表观形态及个体生理活动等方面的差异，发现大叶相思根表覆铁膜显著增加了其耐酸性；在强酸胁迫下，根表有无铁膜的大叶相思植株在渗透调节物质、抗氧化防御系统、内源激素、根系分泌有机酸的数量上具有一定差异；通过探讨强酸胁迫下大叶相思各抗逆调节途径的相互关联，认为根表覆铁膜后超氧化物歧化酶、过氧化物酶和谷胱甘肽过氧化物酶含量增加，帮助大叶相思组织清楚氧自由基并缓解膜脂过氧化；内源激素中，吲哚乙酸在根表有铁膜组分泌增加，可能是维持大叶相思在强酸胁迫下较好生长能力的原因；根表有铁膜组根系分泌柠檬酸、草酸、苹果酸和酒石酸较根表无铁膜组有所增加，推测这些有机酸与大叶相思抵抗根际H+毒害有关。