Ectopic expression of mitochondrial gamma carbonic anhydrase 2 causes male sterility by anther indehiscence

VILLARREAL FERNANDO; MARTÍN VICTORIA; COLANERI ALEJANDRO; GONZÁLEZ-SCHAIN NAHUEL; PERALES MARIANO; MARTÍN MARIANA; LOMBARDO CRISTINA; BRAUN HANS-PETER; BARTOLI CARLOS; ZABALETA EDUARDO

PLANT MOLECULAR BIOLOGY

Springer Netherlands

Lugar: Netherlands ; Año: 2009 vol. 70 p. 471 - 485

0167-4412

Plant mitochondria include gamma-type carbonic anhydrases (γCAs) of unknownfunction. In Arabidopsis, the γCAs form a gene family of five members which all areattached to the NADH dehydrogenase complex (complex I) of the respiratory chain.Here we report a functional analysis of gamma carbonic anhydrase 2 (CA2). The geneencoding CA2 is constitutively expressed in all plant organs investigated but it is tenfold induced in flowers, particularly in tapetal tissue. Ectopic expression of CA2 inArabidopsis causes male sterility in transgenic plants. In normal anther development,secondary thickenings of the endothecial cell wall cause anthers to open upondehydration. Histological analyses revealed that abnormal secondary thickeningprevents anther opening in 35S::CA2 transgenic plants. CA2 abundance in transgenicplants is increased 2–3 fold compared to wild-type plants as revealed by Westernblotting analyses. Moreover, abundance of other members of the CA family, termedCA3 and CAL2, is increased in transgenic plants. Oxygen uptake measurementsrevealed that respiration in transgenic plants is mainly based on NADH reduction by thealternative NADH dehydrogenases present in plant mitochondria. Furthermore, theformation of reactive oxygen species (ROS) is very low in transgenic plants. Wepropose that reduction in ROS inhibits H2O2 dependent lignin polymerization in CA2over-expressing plants, thereby causing male sterility.