ARABIDOPSIS ACTIVATION-TAGGED MUTANTS TOLERANT TO OXIDATIVE STRESS

BONDINO HG; SCARPECI TE; CARRILLO N; VALLE EM

Bariloche

Congreso; SAIB; 2003

Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular (SAIB)

Plants have evolved a dynamic network of antioxidant defenses that serve to reduce the oxidative damage caused by environmental stress. In order to identify new components of this network, we had performed large-scale gain-of-function screenings of Arabidopsis mutants. These activation-tagged mutants were generated by Weigel et al. (2000), who constructed a T-DNA vector (pSKI015) with four copies of an enhancer element from the constitutively active promoter of the cauliflower mosaic virus 35S gene. Seedlings (8.850 lines; segregated into 86 pools) were subjected to oxidative stress by spraying with the herbicide Paraquat (methyl viologen, MV). MV generates superoxide by leakage of electrons at photosystem I in chloroplasts under illumination. Mutants more tolerant to oxidative stress were easily identified in comparison with wild-type lines, which were not able to survive. In a primary screening, 18 putative pools with higher tolerance to MV were isolated. In a secondary screening, 11 lines of mutants displaying strong tolerance to MV were confirmed. Plasmid rescues were carried out to identify the segment of plant DNA adjacent to the activation tag border. The function of the newly identify sequences in the antioxidant defense network will be discussed.