Japanese morning glory dusky mutants displaying.pdf

Japanese morning glory dusky mutants displaying reddish-brown or purplish-gray flowers are deficient in a novel glycosylation enzyme for anthocyanin biosynthesis, UDP-glucose:anthocyanidin 3-O-glucoside-2￠￠-O- glucosyltransferase, due to 4-bp insertions in the gene Yasumasa Morita1, Atsushi Hoshino1, Yasumasa Kikuchi2, Hiroaki Okuhara3, Eiichiro Ono3, Yoshikazu Tanaka3, Yuko Fukui4, Norio Saito5, Eiji Nitasaka6, Hiroshi Noguchi2 and Shigeru Iida1,* 1National Institute for Basic Biology, Okazaki 444-8585, Japan, 2School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka 422-8526, Japan, 3Institute for Advanced Technology, Suntory Ltd, Mishima, Osaka 618-8503, Japan, 4Institute for Health Care Science, Suntory Ltd, Mishima, Osaka 618-8503, Japan, 5Chemical Laboratory, Meiji-Gakuin University, Yokohama 244-8539, Japan, and 6Department of Biological Science, Graduate School of Science, Kyusyu University, Fukuoka 812-8581, Japan Received 28 October 2004; revised 13 January 2005; accepted 21 January 2005. *For correspondence (fax t81 564 55 7685; e-mail shigiida@nibb.ac.jp). Summary Bright blue or red flowers in the Japanesemorning glory (Ipomoea nil) contain anthocyanidin 3-O-sophoroside derivatives, whereas the reddish-brown or purplish-gray petals in its dusky mutants accumulate antho- cyanidin 3-O-glucoside derivatives. The Dusky gene was found to encode a novel glucosyltransferase, UDP-glucose:anthocyanidin 3-O-glucoside-2￠￠-O-glucosyltransferase (3GGT), which mediates the glucosyla- tion of anthocyanidin 3-O-glucosides to yield anthocyanidin 3-O-sophorosides. Ipomoea nil carries one copy of the 3GGT gene that contains no intron and produces 1.6-kbp transcripts mainly in the petals and tubes of flower buds at around 24 h before flower opening. The gene products of both In3GGT in I. nil and Ip3GGT in the common morning glory (Ipomoea purpurea) comprise 459 amino acids and showed a close relationship to the petunia UDP-rhamnose:anthocyanidin 3-O-glucoside-6￠￠