Biological role of miR398 in tobacco

LODEYRO, ANABELLA F.; MARTIN, ANA PAULA; POLI, HUGO O.; CARRILLO, NÉSTOR; PALATNIK, JAVIER F.

San Miguel de Tucumán

Congreso; 45th Annual Meeting - Argentine Society for Biochemestry and Molecular Biology Research; 2009

SOCIEDAD ARGENTINA DE DE INVESTIGACIÓN EN BIOQUÍMICA Y BIOLOGÍA MOLECULAR (SAIB)

MicroRNAs (miRNAs) are a class of non-coding small RNAs of roughly 21 nucleotides. They negatively regulate gene expression at the posttranscriptional level by perfect or nearly-perfect base pairing to complementary target mRNAs. Plant miRNAs were initially reported to be involved in growth and development patterning. Recently, miRNAs have also emerged as a class of gene expression regulators involved in different abiotic stresses. In Arabidopsis, the down-regulation of miR398 expression is important for the induction of the mRNA levels of two Cu/Zn superoxide dismutases (SODs) under high copper levels. SODs form the first line of defense against superoxide radicals. Surprisingly, results obtained in Arabidopsis thaliana indicate that the miR398 system is mainly implicated in copper homeostasis and has a minor role in the response against oxidative stress. In order to investigate the biological role of miR398 in plants from a broader perspective, we prepared transgenic tobacco plants with high levels of the miRNA. Nicotiana tabacum, cv Petit Havana expressing Arabidopsis MIR398a and MIR398b precursors from the 35S viral promoter were prepared. Overexpression of miR398 resulted in the nearly complete inactivation of the Cu/Zn SODs in tobacco, as judge by activity gels. The biological role of the miR398 system in tobacco plants will be discussed.