Linkage mapping, molecular cloning and sunctional analysis of soybean gene Fg2 encoding flavonol 3-O-glucoside (1->6) rhamnosyltransferase

Reference Report for RTN20170322.1

Title:	Linkage mapping, molecular cloning and sunctional analysis of soybean gene Fg2 encoding flavonol 3-O-glucoside (1->6) rhamnosyltransferase
Authors:	Rodas, F.R., Rodriguez, T.O., Murai, Y., Iwashina, T., Sugawara, S., Suzuki, M., Nakabayashi, R., Yonedura-Sakakibara, K., Saito, K., Kitajima, J., Toda, D., Takahashi, R.
Source:	Plant Mol. Biol. 2014, 84:287-300
Abstract:	There are substantial genotypic differences in the levels of flavonol glycosides (FGs) in soybean leaves. The first objective of this study was to identify and locate genes responsible for FG biosynthesis in the soybean genome. The second objective was to clone and verify the function of these candidate genes. Recombinant inbred lines (RILs) were developed by crossing the Kitakomachi and Koganejiro cultivars. The FGs were separated by high performance liquid chromatography (HPLC) and identi- fied. The FGs of Koganejiro had rhamnose at the 600- position of the glucose or galactose bound to the 3-position of kaempferol, whereas FGs of Kitakomachi were devoid of rhamnose. Among the 94 RILs, 53 RILs had HPLC peaks classified as Koganejiro type, and 41 RILs had peaks classified as Kitakomachi type. The segregation fitted a 1:1 ratio, suggesting that a single gene controls FG composi- tion. SSR analysis, linkage mapping and genome database survey revealed a candidate gene in the molecular linkage group O (chromosome 10). The coding region of the gene from Koganejiro, designated as GmF3G600Rt-a, is 1,392 bp long and encodes 464 amino acids, whereas the gene of Kitakomachi, GmF3G600 Rt-b, has a two-base deletion resulting in a truncated polypeptide consisting of 314 amino acids. The recombinant GmF3G600 Rt-a protein converted kaempferol 3-O-glucoside to kaempferol 3-O- rutinoside and utilized 3-O-glucosylated/galactosylated flavonols and UDP-rhamnose as substrates. GmF3G600Rt-b protein had no activity. These results indicate that GmF3G600Rt encodes a flavonol 3-O-glucoside (1 ? 6) rhamnosyltransferase and it probably corresponds to the Fg2 gene. GmF3G600Rt was designated as UGT79A6 by the UGT Nomenclature Committee.

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