Aluminum-Dependent Root Growth Inhibition As Mediated By Dna-Damage Responses

Aluminum (Al) toxicity is a global agricultural problem that reduces crop yields primarily due to root growth inhibition. Several advances in our knowledge of Al resistance mechanisms have recently been made through studies of Al exclusion, yet due to the complicated nature of studying internalized Al, it has proven difficult to determine the biochemical basis of Al toxicity and tolerance. Recent studies show that Al triggers a DNA-damage response mediated by the cell cycle checkpoint ATAXIA TELANGIECTASIA MUTATED AND RAD3-RELATED (ATR). This is an active process that forces terminal differentiation of the root meristem and is at least in part the cause of stoppage of root growth following chronic exposure to Al. Interestingly, unlike well-studied stressors like IR or gamma (gamma) radiation, Al is a real world genotoxic stress that represents a novel system for analysis of DNA damage in biological systems under environmentally relevant conditions. Understanding DNA-damage response and repair pathways following Al treatment in plant systems can offer more effective and safer agricultural practices but also begs to serve as a beacon of caution about Al as a genotoxic stress in other organisms since the cell cycle checkpoint machinery that has been attributed to Al responses is universally found in eukaryotes.