Aluminum Toxicity in Plants: Present and Future

Abstract

Toxic aluminum ions (Al3+) found in acidic soils are absorbed by plants and interact with multiple sites during plant development, affecting especially the root growth. The mechanisms by which plants cope with Al3+ stress are variable, and Al3+ can be excluded or accumulated internally. The molecular and physiological mechanisms associated with Al3+ response have been substantially studied. Thus, reviewing the findings about these mechanisms is important to portrait the state-of-the-art of Al3+ response in plants, highlight key results, identify research gaps, and ask new questions. In this paper, we discuss the current knowledge about DNA damage response induced by Al3+, as well as membrane transporters that avoid Al3+ toxicity in the apoplast, Al3+ exclusion mechanisms, how Al3+ influences plant nutrition, signaling pathways evoked by Al3+ affecting gene expression, changes in plant growth regulators concentrations caused by Al3+ toxicity, and beneficial effects of microorganisms on plants exposed to Al3+ stress. The future research on these topics is also discussed. The current and future knowledge of how plants cope with Al3+ stress is important to comprehend the inter- and intraspecies variability of Al3+ response and to pave the way for new molecular breeding targets that can improve plant performance under Al3+ stress.