Catalase and alternative oxidase cooperatively regulate programmed cell death induced by beta-glucan elicitor in potato suspension cultures.

In potato (Solanum tuberosum L.) suspension cells, the expression of the gene encoding alternative oxidase (AOX) and H2O2 accumulation were induced by treatment with beta-glucan elicitor. The inhibition of catalase activity enhanced both AOX mRNA expression and the production of H2O2, whereas the ascorbate peroxidase inhibitor did not have any effect on these responses. Simultaneous inhibition of catalase and AOX activities in elicited cells dramatically increased H2O2 accumulation, leading to the disruption of mitochondrial membrane potential (deltapsi(m)) and programmed cell death (PCD). The results demonstrate, for the first time, that not only AOX but also catalase plays a central role in the suppression of mitochondrial deltapsi(m) breakdown and PCD induced by beta-glucan elicitor.