Abstract
Major floral scent compounds in Petunia axillaris are benzenoids and their biosynthesis and emission show a day-night rhythm reaching its maximum at nighttime. The metabolomics in corolla indicates that benzenoid precursors, shikimate and glucose metabolites, also showed similar rhythms (Oyama-Okubo et al. 2010). In this study, the expressions of benzenoid-related biosynthetic genes were investigated by transcriptome. Time-course changes of expression levels of these genes did not exactly match to those of correspondent metabolites. Glycolysis genes showed various expression patterns. Expression level of the some pentose phosphate pathway genes, shikimate genes, S-adenosylmethionine cycle genes and non-volatile benzenoid genes showed their maximum at start of nighttime. Interestingly, volatile benzenoid gene expressions increased at daytime, when concentration of benzenoid compounds decreased. These results suggest that regulation by transcriptional levels of biosynthetic genes hardly contribute generation of the day-night rhythms of volatile benzenoids. Expression of the genes grouped by similar time-course change might be regulated by each the same factor.
