| Title: | The monolignol pathway contributes to the biosynthesis of volatile phenylpropenes in flowers |
| Author(s): | Muhlemann JK; Woodworth BD; Morgan JA; Dudareva N; |
| Address: | "Department of Biochemistry, Purdue University, West Lafayette, IN, 47907-2063, USA. School of Chemical Engineering, Purdue University, West Lafayette, IN, 47907-2100, USA" |
| ISSN/ISBN: | 1469-8137 (Electronic) 0028-646X (Linking) |
| Abstract: | "Volatile phenylpropenes play important roles in the mediation of interactions between plants and their biotic environments. Their biosynthesis involves the elimination of the oxygen functionality at the side-chain of monolignols and competes with lignin formation for monolignol utilization. We hypothesized that biochemical steps before the monolignol branch point are shared between phenylpropene and lignin biosynthesis; however, genetic evidence for this shared pathway has been missing until now. Our hypothesis was tested by RNAi suppression of the petunia (Petunia hybrida) cinnamoyl-CoA reductase 1 (PhCCR1), which catalyzes the first committed step in monolignol biosynthesis. Detailed metabolic profiling and isotopic labeling experiments were performed in petunia transgenic lines. Downregulation of PhCCR1 resulted in reduced amounts of total lignin and decreased flux towards phenylpropenes, whereas internal and emitted pools of phenylpropenes remained unaffected. Surprisingly, PhCCR1 silencing increased fluxes through the general phenylpropanoid pathway by upregulating the expression of cinnamate-4-hydroxylase (C4H), which catalyzes the second reaction in the phenylpropanoid pathway. In conclusion, our results show that PhCCR1 is involved in both the biosynthesis of phenylpropenes and lignin production. However, PhCCR1 does not perform a rate-limiting step in the biosynthesis of phenylpropenes, suggesting that scent biosynthesis is prioritized over lignin formation in petals" |
| Keywords: | "Flowers/*metabolism Gene Expression Regulation, Plant/physiology Gene Silencing Molecular Structure Petunia/*metabolism Plant Proteins/genetics/metabolism Propanols/chemistry/*metabolism Protein Transport RNA Interference Volatile Organic Compounds/chemis;" |
| Notes: | "MedlineMuhlemann, Joelle K Woodworth, Benjamin D Morgan, John A Dudareva, Natalia eng Research Support, U.S. Gov't, Non-P.H.S. England 2014/07/06 New Phytol. 2014 Nov; 204(3):661-670. doi: 10.1111/nph.12913. Epub 2014 Jul 2" |
