ECTOPIC EXPRESSION OF GAMMA CARBONIC ANHYDRASES AFFECTS RESPIRATION RATES IN PLANTS

VILLARREAL, F.; MARTIN, M. V.; EDUARDO JULIAN ZABALETA

Rosario

Congreso; 42th Reunion Anual de SAIB; 2006

Arabidopsis thaliana ã-Carbonic Anhydrase 2 (AtãCA2) is a nuclear encoded member of a small protein family present in mitochondria. The submitochondrial localization of these proteins has been established as structural subunits of complex I (NADH:ubiquinone oxidoreductase) forming a plant-specific extra domain. Transgenic plants containing gammaCA2 under the control of 35S promoter express this protein ectopically and show dramatic phenotypic changes causing male sterility by indehiscence of anthers. Western blotting analyses on mitochondrial fractions show increased levels of this protein imported into the mitochondria in derived cell cultures. To analyse this phenotype in more detail, physiological parameters were measured. While CO2 assimilation was unchanged, respiration rate was affected. Reactive Oxygen Species (ROS) production was strongly affected both, in leaves as well as in flowers of transgenic plants. This result is consistent with the variation in respiration rates measured in transgenic leaves as O2 consumption. Transcript coding for proteins involved in redox status and alternative respiration were as well monitored. These data demonstrate the relevance of complex I gammaCAs in mitochondrial respiration. ã-Carbonic Anhydrase 2 (AtãCA2) is a nuclear encoded member of a small protein family present in mitochondria. The submitochondrial localization of these proteins has been established as structural subunits of complex I (NADH:ubiquinone oxidoreductase) forming a plant-specific extra domain. Transgenic plants containing gammaCA2 under the control of 35S promoter express this protein ectopically and show dramatic phenotypic changes causing male sterility by indehiscence of anthers. Western blotting analyses on mitochondrial fractions show increased levels of this protein imported into the mitochondria in derived cell cultures. To analyse this phenotype in more detail, physiological parameters were measured. While CO2 assimilation was unchanged, respiration rate was affected. Reactive Oxygen Species (ROS) production was strongly affected both, in leaves as well as in flowers of transgenic plants. This result is consistent with the variation in respiration rates measured in transgenic leaves as O2 consumption. Transcript coding for proteins involved in redox status and alternative respiration were as well monitored. These data demonstrate the relevance of complex I gammaCAs in mitochondrial respiration.