Microelement Research Center, College of Resources and Environment, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China.
Department of Agronomy, University of Agriculture Faisalabad, 38040 Punjab, Pakistan.
Ecotoxicol Environ Saf. 2018 Dec 15;165:25-35. doi: 10.1016/j.ecoenv.2018.08.087. Epub 2018 Aug 31.
Aluminum is a major limiting abiotic factor for plant growth and productivity on acidic soils. The primary disorder of aluminum toxicity is the rapid cessation of root elongation. The root apex is the most sensitive part of this organ. Although significant literature evidence and hypothesis exist on aluminum toxicity, the explicit mechanism through which aluminum ceases root growth is still indefinable. The mechanisms of tolerance in plants have been the focus of intense research. Some plant species growing on acidic soils have developed tolerance mechanisms to overcome and mitigate aluminum toxicity, either by avoiding entry of Al into roots (exclusion mechanism) or by being able to counterbalance toxic Al engrossed by the root system (internal tolerance mechanism). Genes belonging to ALMT (Aluminum-activated malate transporter) and MATE (Multidrug and toxin compounds extrusion) have been identified that are involved in the aluminum-activated secretion of organic acids from roots. However, different plant species show different gene expression pattern. On the other hand, boron (B) (indispensable micronutrient) is a promising nutrient in the tolerance to aluminum toxicity. It not only hinders the adsorption of aluminum to the cell wall but also improves plant growth. This review mainly explains the critical roles of organic acid and B-induced tolerance to aluminum by summarizing the mechanisms of ALMT, MATE, internal detoxification, molecular traits and genetic engineering of crops.
铝是酸性土壤中植物生长和生产力的主要非生物限制因素。铝毒性的主要紊乱是根伸长的迅速停止。根尖是这个器官最敏感的部分。尽管关于铝毒性存在大量的文献证据和假说，但铝停止根生长的确切机制仍然难以确定。植物的耐受力机制一直是研究的重点。一些在酸性土壤中生长的植物物种已经发展出耐受机制，以克服和减轻铝毒性，要么通过避免铝进入根部（排除机制），要么通过能够抵消根系吸收的有毒铝（内部耐受机制）。已经确定了属于 ALMT（铝激活的苹果酸转运蛋白）和 MATE（多药和毒素化合物外排）的基因，这些基因参与了铝激活的有机酸从根部的分泌。然而，不同的植物物种表现出不同的基因表达模式。另一方面，硼（B）（必需的微量元素）是耐铝毒性的有前途的营养物质。它不仅阻碍了铝对细胞壁的吸附，而且还改善了植物的生长。本文主要通过总结 ALMT、MATE、内部解毒、作物的分子特征和遗传工程等机制，解释了有机酸和 B 诱导的耐铝性的关键作用。
