COPPER-ROOTS: ENGINEERING TRANSGENIC TOBACCO HAIRY ROOTS FOR EXTREME COPPER HYPERACCUMULATION WITH LOW OXIDATIVE STRESS SYMPTOMS

PEREZ PALACIOS P; AGOSTINI E.; IBAÑEZ S; TALANO MA; CAVIEDES MA; RODRIGUEZ LLORENTE I; PAJUELO DOMINGUEZ E

Mar del Plata

Congreso; VIII Encuentro Latinoamericano y del Caribe de Biotecnología REDBIO Argentina 2013; 2013

REDBIO

The aim of this work was developing a biotechnological tool for hyperaccumulation of extreme copper concentrations in a bio-ore. Transgenic tobacco hairy roots (HR) were generated by expressing a copC gene (codifying a Cu-binding protein) from Pseudomonas fluorescens driven by a 35S-promoter. They have been termed COPPER-ROOTS. Two different transgenic roots were generated, by expressing either the copC gene (CR) or the same gene with a signal sequence that targeted the protein to vacuole (CR-V). The maximum Cu concentration accumulated by HR was 45,000 μg.g-1, corresponding to a bioconcentration factor of 40, which is one of the highest Cu concentrations ever reported in a biological sample. In addition, COPPER-ROOTS showed lesser toxicity symptoms, faster growth and higher biomass as compared to control HR, which is an important task in rhizofiltration. Furthermore, CR and CR-V roots usually showed lower activity of several antioxidant enzymes (peroxidase, superoxide dismutase, ascorbate peroxidase) and were less affected by Cu treatment (0.50-50mM) since lower values of malondialdehyde and redox stress index (RSI) were obtained, compared to control roots. Thus, the expression of the gene copC in transgenic HR would be considered as a suitable strategy to obtain hyperaccumulator roots with an alleviation of oxidative stress symptoms. Key words: Agrobacterium rhizogenes, tobacco, vacuole, copC, oxidative stress, bioore