Scent evolution in Chinese roses

Abstract

The phenolic methyl ether 3,5-dimethoxytoluene (DMT) is a major scent compound of many modern rose varieties, and its fragrance participates in the characteristic ''tea scent'' that gave their name to Tea and Hybrid Tea roses. Among wild roses, phenolic methyl ether (PME) biosynthesis is restricted to Chinese rose species, but the progenitors of modern roses included both European and Chinese species (e.g., Rosa chinensis cv Old Blush), so this trait was transmitted to their hybrid progeny. The last steps of the biosynthetic pathways leading to DMT involve two methylation reactions catalyzed by the highly similar orcinol O-methyltransferases (OOMT) 1 and 2. OOMT1 and OOMT2 enzymes exhibit different substrate specificities that are consistent with their operating sequentially in DMT biosynthesis. Here, we show that these different substrate specificities are mostly due to a single amino acid polymorphism in the phenolic substrate binding site of OOMTs. An analysis of the OOMT gene family in 18 species representing the diversity of the genus Rosa indicated that only Chinese roses possess both the OOMT2 and the OOMT1 genes. In addition, we provide evidence that the Chinese-rose-specific OOMT1 genes most probably evolved from an OOMT2-like gene that has homologues in the genomes of all extant roses. We propose that the emergence of the OOMT1 gene may have been a critical step in the evolution of scent production in Chinese roses.flower ͉ volatiles ͉ hybrid tea ͉ dimethoxytoluene

Untangling the hybrid origin of the Chinese tea roses: evidence from DNA sequences of single-copy nuclear and chloroplast genes

“…gigantea and R. chinensis (Ku and Robertson 2003;Scalliet et al 2008; author's observations; Table 3). The four varieties of R. odorata are all lianas with five to seven leaflets and have the same scent compounds (Scalliet et al 2008). They mainly differentiate from one another by double-(semi-double) or single-petaled flowers, floral color, and the size of the petals (Ku and Robertson 2003).…”

“…gigantea (white to creamy-white flowers) and R. chinensis var. spontanea Ku and Robertson (2003), Scalliet et al (2008), and author's observation DMT 3,5-Dimethoxytoluene, TMB 1,3,5-trimethoxybenzene…”

“…The tea scent of hybrid tea roses is mainly due to 3,5-dimethoxytoluene (DMT), a scent compound known primarily from R. odorata var. gigantea (Joichi et al 2005;Scalliet et al 2008). Three teascented China roses (Parsons' Pink China, Hume's Blush Tea-Scented China, and Parks' Yellow Tea-Scented China) of possible origin in Yunnan province of China were introduced into Europe around 1800, crossed with other roses, and produced modern hybrid tea roses (Hurst 1941;Wylie 1954;Joichi et al 2005).…”

Phylogeny of Rosa sections Chinenses and Synstylae (Rosaceae) based on chloroplast and nuclear markers

“…In addition, Rosa lucidissima has a unique character consisting of congested bristles on branchlets, pedicels and receptacles. Because this section includes important garden plants or wild ancestors of cultivated roses, research on this section has been prolific (see Meng et al, 2011;Scalliet et al, 2008;Scariot et al, 2006), but most studies focused on the garden roses or double-petaled varieties. In this study, we sampled all three wild taxa and double-petaled R. odorata (Andrews) Sweet var.…”

A Stress-Inducible Resveratrol O-Methyltransferase Involved in the Biosynthesis of Pterostilbene in Grapevine

“…2) involves two different OOMT1 and OOMT2 enzymes, which operate sequentially to catalyze the first and the second methylation step of orcinol, respectively . The evolution of OOMT1 from the duplicated OOMT2 gene most probably corresponds to an optimization of DMT biosynthesis in Chinese roses (Scalliet et al, 2008). A BLAST search of the genome of the highly homozygous PN40024 grapevine cultivar (Jaillon et al, 2007) identified a small family of four putative ROMT genes located on chromosome 12 (accession nos.…”