UDP-sugar biosynthetic pathway: contribution to cyanidin 3-galactoside biosynthesis in apple skin.
UDP-galactose:flavonoid 3-O-galactosyltransferase (UFGalT) is responsible for cyanidin 3-galactoside (cy3-gal) synthesis from cyanidin (cy) and UDP-galactose (UDP-gal) which are, respectively, catalyzed by anthocyanidin synthase (ANS) and UDP-glucose 4-epimerase (UGE). To clarify the contribution of UDP-galactose pathway to cy3-gal accumulation in apple skin, we analyzed the contents of UDP-gal and UDP-glucose (UDP-glu), cy, and, cy3-gal contents along with UGE activity. We confirmed that transcript levels for apple ANS and UDP-glucose: flavonoid 3-O-glucosyltransferase (UFGT) coincided with anthocyanin accumulation in three apple cultivars differing in their skin colors. During fruit development, changes in level of cy coincided with that of cy3-gal, whereas UDP-gal and UGE activity showed no similar trend with cy3-gal. Significant correlation was not observed between the changes in UGE activity and UDP-sugar contents. The effect of temperature and UV-B radiation (different environmental conditions) on the accumulation of UDP-sugars, cy and cy3-gal, and UGE activity were also investigated in a pale-red cultivar. High temperature tended to depress the accumulation of both UDP-sugars and cy concomitant with the decrease in cy3-gal content irrespective of UV-B radiation. Although there was no high inhibition of both cy and UDP-sugars at low-temperature without UV-B, cy3-gal accumulation was highly depressed. UGE activity was highest at low temperature with UV-B, but not much different under other conditions. Most of the parameters under different environmental conditions were significantly correlated with each other. Based on these results, contribution of UDP-sugar biosynthetic pathway to anthocyanin biosynthesis under different environmental conditions as well as during fruit development is discussed.
Ban
Yusuke
Y
Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan.
Kondo
Satoru
S
Ubi
Benjamin Ewa
BE
Honda
Chikako
C
Bessho
Hideo
H
Moriguchi
Takaya
T
D000383:Agriculture; D000872:Anthocyanins / Q000096:biosynthesis* / Q000378:metabolism; D005638:Fruit / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D005697:Galactosides / Q000096:biosynthesis*; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D027845:Malus / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D053858:Metabolic Networks and Pathways; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D013696:Temperature; D014534:UDPglucose 4-Epimerase / Q000378:metabolism; D014466:Ultraviolet Rays; D014531:Uridine Diphosphate Galactose / Q000096:biosynthesis*; D014532:Uridine Diphosphate Glucose / Q000096:biosynthesis*
D000872:Anthocyanins; D005697:Galactosides; D010940:Plant Proteins; D014531:Uridine Diphosphate Galactose; D014534:UDPglucose 4-Epimerase; C546035:cyanidin 3-galactoside; D014532:Uridine Diphosphate Glucose