The Japanese morning glory (Ipomoea nil) is a traditional and popular floricultural plant in Japan. This species exhibits a wide range of flower color yet mysteriously lacks bright yellow flowers, despite these so-called ‘phantom morning glories’ being repeatedly recorded in block painted picture books published in the late Edo period. Hoshino et al. (on pp. 1871–1879) now report on the generation of yellow flowers by metabolically engineering aurone biosynthesis (a class of yellow flavonoid pigment). Two snapdragon genes for aurone biosynthesis were introduced into a chalcone isomerase mutant with pale yellow flowers. The resultant transgenic plants displayed bright yellow flowers (similar to the phantom morning glories) conferred by the accumulation of two aurone compounds; one matching an aurone known for snapdragon, and the other – a novel aurone.
The cover image shows a transgenic morning glory expressing two snapdragon genes: aureusidin synthase and chalcone 40-O-glucosyltransferase (photographed by Atsushi Hoshino, National Institute for Basic Biology, Japan).