Towards a molecular understanding of Aluminium genotoxicity for crop improvement
Final Report Abstract
Identified already 100 years ago as an important agricultural problem, aluminium (Al) toxicity represents an important limitation to worldwide crop production that is only rivaled by salinity stress. Al toxicity is pH-dependent and manifests itself in acid soils that are pre-dominantly found in developing countries in South America, Central Africa, and Southwest Asia, as well as in eastern North America, Australia, and throughout Europe. Industrial pollution and modern farming practices serve to increase the range and impact of Al toxicity because both contribute to soil acidification. Within the Al-UCIDATE program we aimed at understanding the type of DNA damage induced by Al and the identification of novel regulators involved in the Al-dependent DNA damage response pathway, whereas simultaneously it was tested whether the findings could be extrapolated to a crop species. Through the development of a novel Al sensitivity assay it was demonstrated that Al toxicity goes together with an increase in homologous recombination, whereas cytological analysis showed the occurrence of a G2/M cell cycle arrest and the appearance of micronuclei. The data point to a DNA crosslinking effect of Al, eventually resulting in a loss of genome integrity. Simultaneously, novel candidate genes involved in sensing Al-inflicted DNA damage could be identified through classical genomics, a chemical compound screen and a proteomic based strategy, pinpointing the retinoblastoma and casein kinase II as previously unknown DNA damage regulators. Most importantly, knowledge obtained for Arabidopsis could be transferred to barley, yielding plants with improved Al resistance. Therefore, an important outcome of Al-UCIDATE is the observation that targeting the DNA damage response pathway represents a successful novel strategy conferring Al tolerance to crops.
