Joint NSF/ERA-CAPS: Al-UCIDATE - Towards A Molecular Understanding of Aluminum Genotoxicity for Crop Improvement

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PI: Paul Larsen (University of California-Riverside) ERA-CAPS Collaborators: Lieven DeVeylder (Ghent University, Belgium), Arp Schnittger (Hamburg University, Germany) and Iwona Szarejko (University of Silensia-Katowice, Poland) Aluminum (Al) toxicity is an important limitation to worldwide crop production, occurring in upwards of 50% of the world's arable land. The most evident symptom and important consequence of Al toxicity is root growth inhibition on acidic soils. A prominent example is barley, which is one of the most important crops in temperate regions including Europe and North America. Barley is very sensitive to Al toxicity and yield losses of up to 30% have been associated with growth in acidic soils. It has been previously argued that Al toxicity was an intractable problem due to its apparent complexity. The goal of this project is to define the biochemical mechanism that underlies inhibition of root growth in Arabidopsis and barley following chronic exposure to Al. It is the expectation that an inclusive understanding of this novel process will enable the development of agricultural crop plants that can grow and thrive in the presence of Al. With regard to outreach and training, this project will provide research training opportunities for a diverse group of high school, undergraduate and graduate students from a range of ethnic and social backgrounds. Student training will be enhanced by international research exchanges and collaborations with colleagues from Belgium, Germany and Poland who lead the European ERA-CAPS (http://www.eracaps.org/) companion project entitled "Towards a molecular understanding of aluminium genotoxicity for crop improvement (Al-UCIDATE)". Finally, the project will provide a summer research training internship for a local high school teacher from a local school district that serves a significant Hispanic student population. Aluminum is the most abundant metal in the earth's crust. When found in acidic environments, Al converts to the highly toxic Al3+ form. While the mechanisms of Al exclusion from plants are relatively simple, little is known about the biochemical basis of Al toxicity and why Al leads to severe root growth inhibition with profound effects on yield. Recent work in the model plant Arabidopsis thaliana has shown that Al may act as a genotoxic agent, with DNA damage caused by Al triggering a cell cycle checkpoint pathway that is regulated largely by the cell cycle checkpoint factor Ataxia telangiectasia mutated and RAD3-related (ATR). Specifically, mutations in ATR appear to confer substantial Al tolerance to the plant by suppressing cell cycle progression which forces terminal differentiation of the root in response to Al. The finding that Al acts as a DNA-stress inducing compound represents a new perspective on Al toxicity that bears further investigation. The goal of this project is to study this novel effect of Al on root growth in barley and Arabidopsis using a combination of transcriptomic, phylogenetic, genomic and phenotypic analyses. By developing a model by which root growth is halted following chronic exposure to Al, it is anticipated that the information will enable the exploitation of checkpoint control to confer Al tolerance to economically important crop plants. All data and resources generated through this project will be publicly accessible. Genome, sequence, and proteome datasets will be accessible through a consortium website and through publicly available data repositories that include ArrayExpress (www.ebi.ac.uk/arrayexpress) and the PRIDE Archive (http://www.ebi.ac.uk/pride/archive/) for proteomics data. Biological materials (seeds, plasmids, etc.) will be made available upon request. Seeds of key lines will also be deposited at and disseminated through the appropriate stock centers such as the Arabidopsis Biological Resource Center (ABRC) and Nottingham Arabidopsis Stock Centre (NASC) for Arabidopsis lines.