Effects of gamma-CA2 overexpression on mitochondrial function in Arabidopsis cell cultures and leaves

VILLARREAL FERNANDO; MARTIN VICTORIA; ZABALETA EDUARDO

Tucumán, Argentina

Congreso; XLV Reunión anual de la Sociedad Argentina de investigación Bioquímica y Biología Molecular (SAIB).; 2009

SAIB

We had previously shown that ectopic expression of CA2, one of the A. thaliana gammacarbonicanhydrase gene family, caused male sterility by anther non-dehiscence. Also, leavesfrom overexpressing plants showed an alteration in respiration rates. Particularly, O2 uptake viamitochondrial complex I was nearly null. As CA2 is an Complex I subunit, these data suggesteda mitochondrial dysfunction by CA2 overexpression. In the present work, we studied themitochondrial Complex I functionality in dark-grown, heterotrophic cell cultures, obtained fromboth Col-0 and overexpressing CA2-FLAG tagged plants. We observed that Complex I fromoverexpressing cell cultures presents all the subunits required, and we also confirmed thatNADH dehydrogenase activity remains unaltered. In contrast to the results we obtained inleaves, 35S::CA2-FLAG cell culture shows a higher respiration rate compared to Col-0 cellcultures, and it also yields more fresh weight after one week growth. These results, amongothers, could suggest that CA2 overexpression has different effects over mitochondrialfunctionality (in particular, over Complex I function) depending on growth and light conditions.One possible explanation for this that mitochondrial gamma-CAs function is directly related to alight-related mechanism, i.e. photorespiration.