On the cover: The tulip shows a wide variation in flower color from anthocyanin and carotenoid pigments, but entirely blue colored flowers have not been produced. In many tulip cultivars, the color of the inner bottom of the perianth differs from that of the perianth itself. The cover photo shows a tulip cv. Murasakizuisho which has a purple perianth and a distinct blue color at the bottom. Since the blue coloration is observed only at the bottom of the perianth, some physiological difference may exist in the petals.
In this issue, Shoji et al. (pp. 243-251) report the cause of perianth bottom-specific blue color development of Murasakizuisho by preparing purple and blue protoplasts separately from purple and blue epidermis of petals. The measurement of flavonoid composition, vacuolar pH and element contents revealed the specific accumulation of ferric ions at the blue perianth bottom (Fe content in the blue protoplast was approximately 9.5mM, which was 25 times higher than that in the purple protoplasts). The authors also demonstrated the blue color reproduction by mixing the flavonoids and ferric ion at pH 5.6.
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