SITE II MOTIFS IN ARABIDOPSIS GENES ENCODING COX6 SUBUNITS INFLUENCE RESPONSES TO INDUCING FACTORS

MUFARREGE E, CURI G, GONZALEZ D.

Mar del Plata, Argentina

Congreso; XLIII Reunión Anual de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB); 2007

Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB)

Cytochrome c oxidase (COX) is composed of 3 subunits encoded in the mitochondrial genome and several subunits encoded in the nuclear genome. In plants, 4 polypeptides encoded in the nuclear genome are associated with the enzymatic core: COX5b, COX5c, COX6a and COX6b. In this work we focus in the analysis of the response of the single COX6a and the three COX6b gene promoters from Arabidopsis thaliana towards different factors. We incubated in different conditions transgenic plants that express the gus (b-glucuronidase) gene under the control of COX6a and COX6b promoter sequences and analysed GUS enzymatic activity by fluorometric assays. In this way, we found that the four genes were induced when plants were grown in darkness and in the presence of sucrose. However, each gene showed a different response pattern: COX6a was induced with H2O2, salicylic acid, jasmonic acid, ethylene, abscisic acid, phosphate and auxin; COX6b-1 increased gus expression in the presence of gibberellins, auxins and cytokinins while COX6b-2 showed induction with jasmonic acid and COX6b-3 with ultraviolet light and cytokinins. In transgenic plants that contained COX6a and COX6b promoters with mutations in the site II motifs the induction by most factors disappeared, suggesting that these motifs convey the responses of COX6 genes towards several inducing factors.