Transcriptome and Metabolic Profiling Provides Insigh into Betalain Biosynthesis and Evolution in Mirabilis jalapa  

作　　者：Guy Polturak Uwe Heinig Noam Grossman Maor Battat Dena Leshkowitz Sergey Malitsky liana Rogachev~ and Asaph Aharoni 

机构地区：[1]Department of Plant and Environmental Sciences, Weizmann Institute of Science, 234 Herzl Street, Rehovot 7610001, Israel [2]Bioinformatics Unit, Life Sciences Core Facilities, Weizmann Institute of Science, 234 Herzl Street, Rehovot 7610001, Israel

出　　处：《Molecular Plant》2018年第1期189-204,共16页分子植物（英文版）

摘　　要：Betalains are tyrosine-derived pigments that occur solely in one plant order, the Caryophyllales, where they largely replace the anthocyanins in a mutually exclusive manner. In this study, we conducted multi-species transcriptome and metabolic profiling in Mirabilisjalapa and additional betalain-producing species to identify candidate genes possibly involved in betalain biosynthesis. Among the candidates identified, betalainrelated ytochrome P450 and glucosyltransferase-type genes, which catalyze tyrosine hydroxylation or （hydroxy）cinnamoyl-glucose formation, respectively, were further functionally characterized. We detected the expression of genes in the flavonoid/anthocyanin biosynthetic pathways as well as their metabolite intermediates in betalain-accumulating M. jalapa flowers, and found that the anthocyanin-related gene ANTHOCYANIDIN SYNTHASE （MjANS） is highly expressed in the betalain-accumulating petals. However, it appears that MjANS contains a significant deletion in a region spanning the corresponding enzyme active site. These findings provide novel insights into betalain biosynthesis and a possible explanation for how anthocyanins have been lost in this plant species. Our study also implies a complex, non-uniform history for the loss of anthocyanin production across betalain producers, previously assumed to be strictly due to diminished expression of anthocyanin-related genes.Betalains are tyrosine-derived pigments that occur solely in one plant order, the Caryophyllales, where they largely replace the anthocyanins in a mutually exclusive manner. In this study, we conducted multi-species transcriptome and metabolic profiling in Mirabilisjalapa and additional betalain-producing species to identify candidate genes possibly involved in betalain biosynthesis. Among the candidates identified, betalainrelated ytochrome P450 and glucosyltransferase-type genes, which catalyze tyrosine hydroxylation or （hydroxy）cinnamoyl-glucose formation, respectively, were further functionally characterized. We detected the expression of genes in the flavonoid/anthocyanin biosynthetic pathways as well as their metabolite intermediates in betalain-accumulating M. jalapa flowers, and found that the anthocyanin-related gene ANTHOCYANIDIN SYNTHASE （MjANS） is highly expressed in the betalain-accumulating petals. However, it appears that MjANS contains a significant deletion in a region spanning the corresponding enzyme active site. These findings provide novel insights into betalain biosynthesis and a possible explanation for how anthocyanins have been lost in this plant species. Our study also implies a complex, non-uniform history for the loss of anthocyanin production across betalain producers, previously assumed to be strictly due to diminished expression of anthocyanin-related genes.

关 键 词：BETALAIN ANTHOCYANIN CARYOPHYLLALES plant pigment BIOSYNTHESIS secondary metabolism 

分 类 号：Q111[生物学—普通生物学] TS974.1[轻工技术与工程]