EFFECTS OF gammaCA2 OVEREXPRESSION ON MITOCHONDRIAL FUNCTION IN ARABIDOPSIS CELL SUSPENSIONS AND LEAVES

VILLARREAL, F.; MARTIN, M. V.; ZABALETA, E

San Miguel de Tucumán

Congreso; XLV Reunión Anual SAIB; 2009

We had previously shown that ectopic expression of CA2, one of thegamma-Carbonic Anhydrase integrated Complex I subunits, causesmale sterility by anther non-dehiscence. Also, green leaves fromoverexpressing plants show an alteration in respiration rates.Particularly, O uptake via mitochondrial complex I is nearly null. 2These data suggested a mitochondrial dysfunction by CA2overexpression. In the present work, we studied the mitochondrialComplex I functionality in dark-grown, heterotrophic cellsuspensions, obtained from both Col-0 and overexpressing CA2-FLAG tagged plants. It was observed that Complex I fromoverexpressing cell suspension contains all the required subunits fornormal activity. Indeed, NADH dehydrogenase activity remainsunaltered. In contrast to the results obtained in green leaves,35S::CA2-FLAG cell suspension shows a higher respiration ratethrough Complex I compared to Col-0 cell suspension probablyleading to more fresh weight after one week growth. Thus, CA2overexpression has different effects on mitochondrial functionality(in particular, on Complex I function) depending on growth andlight conditions. These results suggest that mitochondrial gamma-CAs function is directly related to a light-related mechanism, i.e.Photorespiration.