Download S15-08 Functional study of anthocyanidin 3-O-glucoside

S15-08
Functional study of anthocyanidin 3-O-glucoside
glucosyltransferase (Ib3GGT) in purple sweet potato
Hongxia Wang1, Weijuan Fan1, JunYang2 & Peng Zhang1, 2, *
1) National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai
Institutes for Biological Sciences, Chinese Academy of Science, Shanghai 200032, China;
2) Shanghai Key Laboratory of Plant Functional Genomics and Resources, Shanghai Chenshan Plant Science
Research Center, Chinese Academy of Science, Shanghai Chenshan Botanical Garden, Shanghai 201602, China.
*Email: [email protected], Registrant ID# ID 2161
Colorless anthocyanidins are converted into stable colored pigments through glycosylation.
The first step of glycosylation, a same process between Arabidopsis and sweet potato, is to
produce anthocyanidin 3-O-glucosides. Further glycosylation of anthocyanidin 3-Oglucosides, however, is completely different in the two plants. In Arabidopsis, the
glucosyltransferase UGT79B1 catalyzes the conversion of UDP-xylose and anthocyanidin 3O-glucosides to anthocyanidin-3-O-xylosyl-2-O-glucoside. In sweet potato, the step is to
form anthocyanidin 3-O-sophorosides by adding a glucose molecule to anthocyanidin 3-Oglucosides via a novel glucosyltransferase, UDP-glucose:anthocyanidin-3-O-glucoside-2-Oglucosyltransferase (3GGT, GenBank No.: ABL74480). The Ib3GGT protein expressed in yeast
could catalyze substrates UDPG and cyanidin 3-O-glucoside to form cyanidin 3-Osophoroside specifically. Whereas cyanidin, cyanidin 3,5-O-diglucoside or quercetin 3-Oglucoside could not be used as a substrate. In the transgenic Arabidopsis constitutively
expressing Ib3GGT, the new compound cyanidin 3-O-sophoroside was detected by LC-MS
analysis, confirming that the Ib3GGT was a glucosyltransferase that catalyzed the substrates
anthocyanidin 3-O-glucosides into anthocyanidin 3-O-sophorosides in vivo. The Ib3GGT
localized in endoplasmic reticulum and Golgi apparatus, indicating the anthocyanin
modification is occurred in these subcellular organelles before transport to vacuole. Up- or
down-regulation of Ib3GGT expression also affect anthocyanin accumulation and
composition in vacuoles of sweet potato plants. The study elucidates the biological function
of Ib3GGT in anthocyanidin glycosylation, which can provide the fundamental knowledge
and new approaches for anthocyanin improvement in crops.