Cit1, 2RhaT and two novel CitdGlcTs participate in flavor-related flavonoid metabolism during citrus fruit development. (6th March 2019)

• Record Type: Journal Article
• Authors: Chen, Jiajing; Yuan, Ziyu; Zhang, Haipeng; Li, Wenyun; Shi, Meiyan; Peng, Zhaoxin; Li, Mingyue; Tian, Jing; Deng, Xiuxin; Cheng, Yunjiang; Deng, Cecilia Hong; Xie, Zongzhou; Zeng, Jiwu; Yao, Jia-Long; Xu, Juan
• Is Part Of: Journal of experimental botany. Volume 70:Number 10(2019)
• Page Start: 2759
• Page End: 2771
• Publication Date: 2019-03-06
• Subjects: Bitterness -- citrus -- flavonoid -- flavonoid-7-O-di-glucosides -- flavonoid-7-O-glucoside -- neohesperidoside; Botany -- Periodicals; Botany, Experimental -- Periodicals; Plant physiology -- Periodicals; 580
• DOI: 10.1093/jxb/erz081
• Languages: English
• ISSNs: 0022-0957

Abstract

Abstract: Neohesperidosides are disaccharides that are present in some flavonoids and impart a bitter taste, which can significantly affect the commercial value of citrus fruits. In this study, we identified three flavonoid-7- O - di -glucosyltransferase ( dGlcT ) genes closely related to 1, 2-rhamnosyltransferase ( 1, 2RhaT ) in citrus genomes. However, only 1, 2RhaT was directly linked to the accumulation of neohesperidoside, as demonstrated by association analysis of 50 accessions and co-segregation analysis of an F1 population derived from Citrus reticulata × Poncirus trifoliata . In transgenic tobacco BY2 cells, over-expression of CitdGlcT s resulted in flavonoid-7- O -glucosides being catalysed into bitterless flavonoid-7- O - di -glucosides, whereas over-expression of Cit1, 2RhaT converted the same substrate into bitter-tasting flavonoid-7- O -neohesperidoside. Unlike 1, 2RhaT, during citrus fruit development the dGlcT s showed an opposite expression pattern to CHS and CHI, two genes encoding rate-limiting enzymes of flavonoid biosynthesis. An uncoupled availability of dGlcTs and substrates might result in trace accumulation of flavonoid-7- O - di -glucosides in the fruit of C. maxima (pummelo). Past human selection of the deletion and functional mutation of 1, 2RhaT has led step-by-step to the evolution of the flavor-related metabolic network in citrus. Our research provides the basis for potentially improving the taste in citrus fruit through manipulation of the network by knocking-out 1, 2RhaT or by enhancing the expression of dGlcT using genetic transformation. Abstract : Coupled availability of the Cit1, 2RhaT enzyme and flavanone-7- O -glucosides promote the biosynthesis of bitter-tasting neohesperidosides during early fruit development in citrus, and selection against Cit1, 2RhaT has occurred during domestication.