Ectopic expression of gammaCA2 causes male sterility by anther indehiscence

VILLARREAL, F.; MARTIN, M. V.; COLANERI, A.; GONZÁLEZ-SCHAIN, N.; PERALES, M.; MARTIN, M.; LOMBARDO, C.; BRAUN, H.; BARTOLI, C.; EDUARDO JULIAN ZABALETA

PLANT MOLECULAR BIOLOGY

SPRINGER

Año: 2009 vol. 70 p. 481 - 485

0167-4412

Abstract Plant mitochondria include gamma-type carbonicanhydrases (cCAs) of unknown function. InArabidopsis, the cCAs form a gene family of five memberswhich all are attached to the NADH dehydrogenase complex(complex I) of the respiratory chain. Here we report afunctional analysis of gamma carbonic anhydrase 2 (CA2).The gene encoding CA2 is constitutively expressed in allplant organs investigated but it is ten fold induced inflowers, particularly in tapetal tissue. Ectopic expression ofCA2 in Arabidopsis causes male sterility in transgenicplants. In normal anther development, secondary thickeningsof the endothecial cell wall cause anthers to open upondehydration. Histological analyses revealed that abnormalsecondary thickening prevents anther opening in 35S::CA2transgenic plants. CA2 abundance in transgenic plants isincreased 2?3 fold compared to wild-type plants asrevealed by Western blotting analyses. Moreover, abundanceof other members of the CA family, termed CA3 andCAL2, is increased in transgenic plants. Oxygen uptakemeasurements revealed that respiration in transgenic plantsis mainly based on NADH reduction by the alternativeNADH dehydrogenases present in plant mitochondria.Furthermore, the formation of reactive oxygen species(ROS) is very low in transgenic plants. We propose thatreduction in ROS inhibits H2O2 dependent lignin polymerizationin CA2 over-expressing plants, thereby causingmale sterility.