Gene expression analysis of the ATP-binding cassette transporter ABCD1 in petunia (Petunia hybrida) and tobacco (Nicotiana spp.)

Most plant metabolites are biosynthesized via organelles, including peroxisome. From the mutant analyses, Arabidopsis ATP-binding cassette (ABC) transporter ABCD1 is reported to be implicated in the peroxisomal import of β-oxidation substrates, which are biosynthetic intermediates for central and specialized metabolites. However, little was explored about ABCD1 in plants except for AtABCD1 and two barley homologs, HvABCD1 and 2. The present study investigated the expression profiles of ABCD1 genes of petunia and tobacco that produce various metabolites, including volatile benzenoid/phenylpropanoids (VBPs) and ubiquinone. PhABCD1 expression was ubiquitous and at particularly high levels (2.2- to 2.8-fold compared to roots) in leaves, limbs, and tubes. NsABCD1 was expressed in roots, stems, leaves, sepals, and flowers; specifically, a relatively high expression level (3.2-fold compared to roots) was observed in sepals. Yeast extract and methyl jasmonate induced the expression of the NtABCD1 gene significantly (1.3- and 2.5-fold, respectively) in N. tabacum BY-2 cells. These results suggest that the expression of ABCD1 would be related to the biosynthesis of metabolites beneficial for plant environmental adaptation in petunia and tobacco. The current study provides new insights into the mechanism of metabolite biosynthesis and ABC transporter function in Solanaceae plants.