The COMATOSE ABC transporter is required for full fertility in Arabidopsis

A and Theodoulou, FL (2007) The COMATOSE ATP-binding cassette transporter is required for full fertility in arabidopsis. BBSRC of the UK. The metabolite analysis performed at the Max-Planck–Institute was supported by a grant from the Minerva foundation to AF. 4 ABSTRACT COMATOSE (CTS) encodes a peroxisomal ABC transporter required not only for β-oxidation of storage lipid during germination and establishment but also for biosynthesis of jasmonic acid (JA) and conversion of indole butyric acid (IBA) to indole acetic acid (IAA). cts mutants exhibited reduced fertilisation which was rescued by genetic complementation but not by exogenous application of JA or IAA. Reduced fertilisation was also observed in thiolase (kat2-1) and peroxisomal acyl-CoA synthetase mutants (lacs6-1 lacs7-1), indicating a general role for β-oxidation in fertility. Genetic analysis revealed reduced male transmission of cts alleles and both cts pollen germination and tube growth in vitro were impaired in the absence of an exogenous carbon source. No differences between mutant and wild-type pollen were observed in the presence of sucrose. Aniline blue staining of pollinated pistils demonstrated that pollen tube growth was affected only when both parents bore the cts mutation, indicating that the expression of CTS in either male or female tissues was sufficient to support pollen tube growth in vivo. Accordingly, abundant peroxisomes were detected in a range of maternal tissues. Although GABA levels were reduced in flowers of cts mutants, they were unchanged in kat2-1, suggesting that alterations in GABA catabolism do not contribute to the reduced fertility phenotype through altered pollen tube targeting. Taken together, our data support an important role for β-oxidation in fertility in Arabidopsis and suggest that this pathway could play a role in the mobilisation of lipid in both pollen and female tissues.