Frelet-Barrand, Annie Kolukisaoglu, H. Üner Plaza, Sonia Rüffer, Maika Azevedo, Louis Hörtensteiner, Stefan Marinova, Krasimira Weder, Barbara Schulz, Burkhard Klein, Markus 2008 The enormous metabolic plasticity of plants allows detoxification of many harmful compounds that are generated during biosynthetic processes or are present as biotic or abiotic toxins in their environment. Derivatives of toxic compounds such as glutathione conjugates are moved into the central vacuole via ATP-binding cassette (ABC)-type transporters of the multidrug resistance-associated protein (MRP) subfamily. The Arabidopsis genome contains 15 <i>AtMRP</i> isogenes, four of which (<i>AtMRP1</i>, <i>2</i>, <i>11</i> and <i>12</i>) cluster together in one of two major phylogenetic clades. We isolated T-DNA knockout alleles in all four highly homologous <i>AtMRP</i> genes of this clade and subjected them to physiological analysis to assess the function of each <i>AtMRP</i> of this group. None of the single <i>atmrp</i> mutants displayed visible phenotypes under control conditions. In spite of the fact that AtMRP1 and AtMRP2 had been described as efficient ATP-dependent organic anion transporters in heterologous expression experiments, the contribution of three of the <i>AtMRP</i> genes (<i>1</i>, <i>11</i> and <i>12</i>) to detoxification is marginal. Only knockouts in <i>AtMRP2</i> exhibited a reduced sensitivity towards 1-chloro-2,4-dinitrobenzene, but not towards other herbicides. <i>AtMRP2</i> but not <i>AtMRP1</i>, <i>11</i> and <i>12</i> is involved in chlorophyll degradation since ethylene-treated rosettes of <i>atmrp2</i> showed reduced senescence, and <i>AtMRP2</i> expression is induced during senescence. This suggests that AtMRP2 is involved in vacuolar transport of chlorophyll catabolites. Vacuolar uptake studies demonstrated that transport of typical MRP substrates was reduced in <i>atmrp2</i>. We conclude that within clade I, only <i>AtMRP2</i> contributes significantly to overall organic anion pump activity in vivo. application/pdf https://folia.unifr.ch/global/documents/300656 https://folia.unifr.ch/documents/300656/files/pcn034.pdf eng info:eu-repo/semantics/altIdentifier/doi/10.1093/pcp/pcn034 info:eu-repo/semantics/openAccess License undefined Plant and Cell Physiology. - 2008, vol. 49, no. 4, p. 557-569 Arabidopsis thaliana gene family herbicide resistance organic anion transport senescence T-DNA knockout info:eu-repo/classification/udc/57 Comparative mutant analysis of Arabidopsis ABCC-type ABC transporters: AtMRP2 contributes to detoxification, vacuolar organic anion transport and chlorophyll degradation http://purl.org/coar/resource_type/c_6501