Anthocyanin accumulation and related gene expression in Japanese parsley (Oenanthe stolonifera, DC.) induced by low temperature

Low temperature was found to induce the accumulation of anthocyanins in Japanese parsley (Oenanthe stolonifera, DC.), and cyanidin was identified as their major component. Among three cultivars, cv. Jizeri responded most strongly to low-temperature stress, accumulating four-fold higher anthocyanin levels in leaves of plants grown at 12 °C compared with those at 25 °C. RNA gel-blot analysis showed that expression of the dihydroflavonol 4-reductase gene (dfr) was especially affected by low temperature. In the cv. Jizeri, the dfr transcripts were rapidly induced 6 to 7 days after transfer to low-temperature conditions, whereas dfr expression was scarcely observed in the non-pigmented cultivar (cv. Matsuemidori). The phenylalanine ammonia-lyase gene (pal) and chalcone synthase gene (chs) seemed to be expressed coordinately at both 12 °C and 25 °C in both cultivars. The pal and chs genes comprised multigene families, while the dfr gene was detected as being unique. These results suggest that the mechanism regulating dfr expression differs from those for pal and chs expression in Japanese parsley, and that dfr expression is a key step in the regulation by low-temperature stress in the temperature-sensitive cultivars of Japanese parsley.