Family-wide expression characterization of Arabidopsis beta-carbonic anhydrase genes using qRT-PCR and Promoter::GUS fusions

Carbonic anhydrases (CAs, EC 4.2.1.1) are metalloenzymes found throughout the phylogenetic tree. The beta-class carbonic anhydrases (beta-CAs) are the predominating class of CAs in plants. Growing evidence underscores the importance of beta-CAs in plant immunity and environmental adaptation in addition to their roles in photosynthesis. However, many fundamental problems in Arabidopsis beta CAs expression remain unsolved. Here we examined the transcript abundance of At beta CAs in different tissues of Arabidopsis thaliana, and the accumulation of mRNA in response to CO2 and darkness. Histochemical analysis was performed to study the promoter activity of At beta CAs during post-germination seedling growth and in mature plants. All six members of the At beta CA subfamily showed a response to changed CO2 level and darkness, but each member showed a specific dynamic pattern. Although expression of each At beta CA was unique, in general most At beta CAs were synchronously expressed in green leaves since 5 days after germination until flowering. At beta CA1 and At beta CA2 were most highly expressed in leaves but At beta CA2 displayed weaker expression in roots. The level of At beta CA3 transcripts was highest in flowers, while At beta CA5 was most widely expressed and might be involved in more processes than other members. At beta CA6 was unique for increased expression in darkness and no expression in either the anther or pistil. The present study provides useful information for further functional investigation. (C) 2013 Elsevier Masson SAS. All rights reserved.