Antioxidative responses of cell suspension cultures of two Coffea arabica varieties to low aluminum levels at pH 5.8

ABSTRACT- (Antioxidative responses of cell suspension cultures of two Coffea arabica varieties to low aluminum levels at pH 5.8). The effects of aluminum (Al) on the activities of antioxidant enzymes and ferritin expression were studied in cell suspension cultures of two varieties of Coffea arabica, Mundo Novo and Icatu, in medium with pH at 5.8. The cells were incubated with 300 μM Al3+, and the Al speciation as Al3+ was 1.45 % of the mole fraction. The activities of superoxide dismutase (SOD), catalase (CAT), and glutathione S-transferase (GST) were increased in Mundo Novo, whereas glutathione reductase (GR) and guaiacol peroxidase (GPOX) activities remained unchanged. SOD, GR, and GST activities were increased in Icatu, while CAT activity was not changed, and GPOX activity decreased. The expression of two ferritin genes (CaFer1 and CaFer2) were analyzed by Real-Time PCR. Al caused a downregulation of CaFER1 expression and no changes of CaFER2 expression in both varieties. The Western blot showed no alteration in ferritin protein levels in Mundo Novo and a decrease in Icatu. The differential enzymes responses indicate that the response to Al is variety-dependent. Key words: aluminum toxicity, antioxidant enzymes, ferritin, oxidative stress RESUMO- (Resposta antioxidante de células em suspensão de duas variedades de Coffea arabica submetidas à baixa concentração de alumínio em pH 5.8). Foram estudadas a atividade de enzimas antioxidantes e a expressão da ferritina em culturas celulares de duas variedades de Coffea arabica, Mundo Novo e Icatu, tratadas com alumínio (Al) em meio de cultura com pH 5.8. As células foram incubadas com 300 μM Al3+, e a especiação do Al para Al3+ foi de 1.45%. Para Mundo Novo