Genetic and Biochemical Aspects of Floral Scents in Roses

Abstract

Floral scents possess high ornamental and economic values to rose production in the floricultural industry. In the past two decades, molecular bases of floral scent production have been studied in the rose as well as their genetic inheritance. Some significant achievements have been acquired, such as the comprehensive rose genome and the finding of a novel geraniol synthase in plants. In this review, we summarize the composition of floral scents in modern roses, focusing on the recent advances in the molecular mechanisms of floral scent production and emission, as well as the latest developments in molecular breeding and metabolic engineering of rose scents. It could provide useful information for both studying and improving the floral scent production in the rose.

Keywords: Rosa; benzenoids; floral scents; molecular breeding; phenylpropanoids; terpenoids.

Figure 1

Synthesis pathways of floral scents in roses. (A) The biosynthesis pathway of terpenoids in roses. (B) Biosynthesis pathway of phenylpropanoids/benzenoids in roses. Solid lines indicate established biochemical reactions, and broken lines indicate possible steps. G3P: glyceraldehyde-3-phosphate; DXS: 1-deoxy-D-xylulose-5-phosphate synthase; DXR: 1-deoxy-D-xylulose-5-phosphate reductoisomerase; IPP: isopentenyl pyrophosphate; DMAPP: dimethylallyl pyrophosphate; GPP: geranyl pyrophosphate; GPPS: GPP synthase; GGPP, geranylgeranyl pyrophosphate; NUDX: nudix hydrolase; LIS: linalool synthase; AAT: alcohol acetyltransferase; CCD: carotenoid cleavage (di-)oxygenase; FPP: farnesyl pyrophosphate; PAL: phenylalanine ammonia lyase; PAAS: phenylacetaldehyde synthase; AADC: aromatic amino acid decarboxylase; AAAT: aromatic amino acid aminotransferase; PPA: phenylpyruvic acid; PAA: phenyl acetaldehyde; PAR: phenyl acetaldehyde reductase; PPDC: phenylpyruvate decarboxylase; 2-PE: 2-phenylethanol; POMT: phloroglucinol O-methyltransferase; OMT: O-methyltransferases; OOMT: orcinol O-methyltransferases; MHT: 3-methoxy-5-hydroxytoluene; DMT: 3,5-dimethoxy toluene; DHA: 3,5-dihydroxy antisole; DMP: 3,5-dimethoxy phenol; TMB: 1,3,5-trimethoxy benzene.

Figure 1

Synthesis pathways of floral scents in roses. (A) The biosynthesis pathway of terpenoids in roses. (B) Biosynthesis pathway of phenylpropanoids/benzenoids in roses. Solid lines indicate established biochemical reactions, and broken lines indicate possible steps. G3P: glyceraldehyde-3-phosphate; DXS: 1-deoxy-D-xylulose-5-phosphate synthase; DXR: 1-deoxy-D-xylulose-5-phosphate reductoisomerase; IPP: isopentenyl pyrophosphate; DMAPP: dimethylallyl pyrophosphate; GPP: geranyl pyrophosphate; GPPS: GPP synthase; GGPP, geranylgeranyl pyrophosphate; NUDX: nudix hydrolase; LIS: linalool synthase; AAT: alcohol acetyltransferase; CCD: carotenoid cleavage (di-)oxygenase; FPP: farnesyl pyrophosphate; PAL: phenylalanine ammonia lyase; PAAS: phenylacetaldehyde synthase; AADC: aromatic amino acid decarboxylase; AAAT: aromatic amino acid aminotransferase; PPA: phenylpyruvic acid; PAA: phenyl acetaldehyde; PAR: phenyl acetaldehyde reductase; PPDC: phenylpyruvate decarboxylase; 2-PE: 2-phenylethanol; POMT: phloroglucinol O-methyltransferase; OMT: O-methyltransferases; OOMT: orcinol O-methyltransferases; MHT: 3-methoxy-5-hydroxytoluene; DMT: 3,5-dimethoxy toluene; DHA: 3,5-dihydroxy antisole; DMP: 3,5-dimethoxy phenol; TMB: 1,3,5-trimethoxy benzene.