title: miR398 and miR408 are up-regulated in response to water deficit in Medicago truncatula.
abstract: Plant microRNAs have been implicated in various abiotic stress responses. We identified several conserved microRNAs that showed differential expression in Medicago truncatula plants subjected to water deficit: miR169 is down-regulated only in the roots and miR398a/b and miR408 are strongly up-regulated in both shoots and roots. Down-regulation of miR169 in the roots did not correlate with accumulation of its target MtHAP2-1 transcripts, suggesting that its regulation may not occur at the mRNA level or may depend on other regulatory mechanisms, which do not involve this miRNA, in water-deficit conditions. The up-regulation of miR398a/b and miR408 and the clear down-regulation of their respective target genes, which encode the copper proteins COX5b (subunit 5b of mitochondrial cytochrome c oxidase) and plantacyanin, highlight the involvement of these miRNAs in response to water deprivation in M. truncatula. Also, miR398 up-regulation is inversely correlated with the down-regulation of copper superoxide dismutase, CSD1, during water deficit. The regulation of genes encoding copper proteins by miR398a/b and miR408 suggests a link between copper homeostasis and M. truncatula adaptation to progressive water deficit.
authors.affiliation: Laboratório de Biotecnologia de Células Vegetais, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Apartado 127, 2781-901 Oeiras, Portugal. inest@itqb.unl.pt
authors.forename: Inês
authors.initials: I
authors.lastname: Trindade
authors.forename: Cláudio
authors.initials: C
authors.lastname: Capitão
authors.forename: Tamas
authors.initials: T
authors.lastname: Dalmay
authors.forename: Manuel Pedro
authors.initials: MP
authors.lastname: Fevereiro
authors.forename: Dulce Metelo Dos
authors.initials: DM
authors.lastname: Santos
mesh_terms: D019295:Computational Biology; D003300:Copper / Q000378:metabolism; D018745:Genome, Plant; D006706:Homeostasis; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D010940:Plant Proteins / Q000378:metabolism; D012503:Saponins / Q000235:genetics*; D014315:Triterpenes; D015854:Up-Regulation; D014867:Water
chemical_list: D035683:MicroRNAs; D010940:Plant Proteins; D012503:Saponins; D014315:Triterpenes; D014867:Water; C089067:medicago-saponin P(1); D003300:Copper