2024 Volume 93 Issue 2 Pages 185-193
Flowers of the early Polyantha roses, ‘Pâquerette’, ‘Mignonette’ and ‘Anne-Marie de Montravel’, have an unusual odor not found in other roses. Their ancestor is Rosa multiflora, a wild species native to Japan. In particular, ‘Anne-Marie de Montravel’ has a citrus scent with an old wooden closet-like odor. Gas chromatography (GC)-mass spectrometry analysis of the scent components of these roses revealed the presence of several terpenoids, benzenoids, and hydrocarbons, as well as the fatty acid derivatives methyl (E, Z)-2,4-decadienoate (MDD) and methyl (E, E, Z)-2,4,6-decatrienoate (EEZ-MDT). GC-olfactometry analysis of scent components of ‘Anne-Marie de Montravel’, identified EEZ-MDT and its isomers as the source of the unpleasant odor. MDD and EEZ-MDT are known as stink bug pheromones, but they were first detected in the scent of plants. We also analyzed the floral scent of several roses related to R. multiflora, namely: two plants of R. multiflora, two Hybrid Multiflora roses (‘Crimson Rambler’ and ‘Rose-Marie Viaud’), eight Polyantha roses (‘Cécile Brunner’, ‘Clothilde Soupert’, ‘Gloire des Polyantha’, ‘Madame Norbert Levavasseur’, ‘Marie Daly’, ‘Marie Pavié’, R. multiflora ‘Nana’, ‘Yvan Misson’), and one Miniature rose (‘Gourmet Popcorn’). EEZ-MDT and/or its isomers were detected not only in ‘Marie Daly’, ‘Marie Pavié’, R. multiflora ‘Nana’, and ‘Gourmet Popcorn’, which had an old wooden closet-like odor, but also in R. multiflora, ‘Rose-Marie Viaud’ and ‘Yvan Misson’, which do not exhibit that unpleasant odor. To produce the unusual odor in the rose fragrance, the EEZ-MDT and its isomers content must be above a certain percentage of the scent components.
The scent of roses is a complex blend of various compounds exhibiting a wide range of sensory qualities, such as the characteristic rose-like fragrance and fruit-like and black tea-like scents. Generally, the scent of roses is regarded as a pleasant fragrance, but there are also less appealing odors for humans, notably those with fatty undertones, such as the scent of Rosa foetida Herrm. flowers (Oyama-Okubo and Mikanagi, 2023).
There are horticultural groups of cultivars in the genus Rosa that are derived from an Asian wild rose, Rosa multiflora Thunb. Among them, the horticultural group Polyantha has been developed from R. multiflora, which was introduced to Europe from Japan in the late 19th century (Harkness, 1978). At that time, R. multiflora was called R. polyantha Siebold et Zucc. in France. As a result, this horticultural group was designated as the horticultural group Polyantha (Krüssmann, 1981a). The name derives from the Greek word “polyanthos = many-flowered”, and this horticultural group is characterized by having clusters of numerous small flowers. The horticultural group Polyantha is also characterized by its continuous bloom throughout the season and its low-growing, dwarf habit.
The first Polyanthas, ‘Pâquerette’ and ‘Mignonette’, were raised by Jean-Baptiste André Guillot in France in 1872. Their parentage is unknown as they were selected from F2 seedlings of R. multiflora from Japan, however, it is assumed that the F1 seedlings, double flowered varieties of R. multiflora were pollinated by a China rose to produce these cultivars (Dickerson, 1992; Harkness, 1978; Sisley, 1886). ‘Anne-Marie de Montravel’ was raised by Joseph Rambaux in France before 1879 and supposedly produced from a cross between a double-flowered variety of R. multiflora and a Tea rose ‘Madame de Tartas’ (Dickerson, 1992; Ellwanger 1892). Of these early Polyantha roses, ‘Mignonette’ holds a significant importance in the history of rose breeding, contributing substantially to the birth of many Polyantha rose cultivars (Thomas, 1962).
At the beginning of the 20th century, crosses between Polyantha and Hybrid Tea roses produced the horticultural group Floribunda (Krüssmann, 1981b). With the birth of this new horticultural group, the many-flowered habit of R. multiflora was introduced into modern roses.
These early Polyantha roses, ‘Pâquerette’, ‘Mignonette’ and ‘Anne-Marie de Montravel’, have an unusual odor not found in other roses. In particular, ‘Anne-Marie de Montravel’ exhibits a citrus scent with an old, sweet woody scent reminiscent of the smell of old wooden closets.
In this study, we analyzed the scent components of the flowers of these three early Polyantha cultivars and identified the compounds responsible for the uncommon “old wooden closets” odor. We also analyzed the floral scent of two R. multiflora plants, ancestors of Polyantha roses, two Hybrid Multiflora rose cultivars, eight Polyantha rose cultivars, and one Miniature rose cultivar whose ancestors are Hybrid Multiflora and Polyantha roses. We also investigated the distribution of the unusual odors and their causative compounds.
Roses were grown in rose gardens (Echigo Hillside Park, Hamadera Park, Himeno Rose Nursery, Keisei Rose Garden, The City of Sakura Rose Garden, Yokohama English Garden) and green houses of the Institute of Vegetable and Floricultural Science, NARO. The following cultivars were used: ‘Anne-Marie de Montravel’ (Old Polyantha (Pol); a double-flowered variety of R. multiflora × ‘Madame de Tartas’, bred by Joseph Rambaux, before 1879), ‘Mignonette’ (Old Pol; a double-flowered variety of R. multiflora × a China Rose, bred by Jean-Baptiste André Guillot, 1872), ‘Pâquerette’ (Old Pol; a double-flowered variety of R. multiflora × a China Rose, bred by Jean-Baptiste André Guillot, 1872), ‘Cécile Brunner’ (Pol; a double-flowered variety of R. multiflora × ‘Madame de Tartas’, bred by Marie aka Veuve Ducher, before 1880), ‘Clothilde Soupert’ (Pol; ‘Mignonette’ × ‘Madame Damaizin’, bred by Soupert & Notting, 1888), ‘Crimson Rambler’ (Hybrid Multiflora (HMult); brought from Japan to the United Kingdom by Robert Smith before 1890, introduced by Charles Turner in 1893), ‘Gloire des Polyantha’ (Pol; seedling of ‘Mignonette’, bred by Jean-Baptiste André Guillot, 1886), ‘Gourmet Popcorn’ (Miniature (Min); sport of ‘Popcorn’, discovered by Luis Desamero, 1986), ‘Madame Norbert Levavasseur’ (Pol; ‘Crimson Rambler’ × ‘Gloire des Polyantha’, bred by Ernest Levavasseur, 1903), ‘Marie Daly’ (Pol; sport of ‘Marie Pavié’, discovered by Greg Grant, 2002), ‘Marie Pavié’ (Pol; parentage unknown, bred by Alphonse Alégatière, 1888), R. multiflora ‘Nana’ (Pol; parentage unknown, bred by Léonard Lille, 1891), R. multiflora (wild species; two plants from Keisei and Echigo), ‘Rose-Marie Viaud’ (HMult; seedling of ‘Veilchenblau’, bred by Igoult, 1924), ‘Yvan Misson’ (Pol; ‘Jeanny Soupert’ × ‘Katharina Zeimet’, bred by Soupert & Notting, 1922) (Fig. 1). Places and dates of floral scent materials collection are listed in Table S1.
Plant materials. (A) ‘Anne-Marie de Montravel’. (B) ‘Mignonette’. (C) ‘Pâquerette’. (D) ‘Cécile Brunner’. (E) ‘Clothilde Soupert’. (F) ‘Crimson Rambler’. (G) ‘Gloire des Polyantha’. (H) ‘Gourmet Popcorn’. (I) ‘Madame Norbert Levavasseur’. (J) ‘Marie Daly’. (K) ‘Marie Pavié’. (L) Rosa multiflora ‘Nana’. (M) R. multiflora (Keisei). (N) R. multiflora (Echigo). (O) ‘Rose-Marie Viaud’. (P) ‘Yvan Misson’. Scale bar = 1 cm.
An absorbent (Twister, a magnetic stir bar coated with a partitioning phase of 100% polydimethylsiloxane; Gerstel Inc., Mülheim, Germany) was used to collect floral scents. From April 2021 to May 2023, we selected flowers in a rose garden at 70% bloom before anthers had opened. Floral scents were collected from two to nine flowers for each cultivar; nine flowers of ‘Anne-Marie de Montravel’; four flowers of ‘Pâquerette’, ‘Clothilde Soupert’, ‘Gloire des Polyantha’, ‘Gourmet Popcorn’, ‘Madame Norbert Levavasseur’, ‘Marie Daly’, ‘Marie Pavié’, R. multiflora ‘Nana’ and R. multiflora (2 plants from Keisei and Echigo); and two flowers from others. A Twister was clipped to the inside of a petal such that it did not touch the anthers or the petals. The whole flower was covered with a transparent wrapper (Saran Wrap; Asahi KASEI, Tokyo, Japan) and the scent compounds were collected over a one-hour period (Oyama-Okubo and Mikanagi, 2023; Oyama-Okubo and Tsuji, 2013). Collected samples were stored in a tightly closed container until analysis.
Analysis of emitted floral volatilesSamples were directly introduced into a GC (capillary gas chromatography)-MS (mass spectrometry) using a thermal desorption unit (TDU; Gerstel Inc., Linthicum, MD, USA) and a cooling injection system (CIS4; Gerstel Inc.). GC-MS was performed using an Agilent 7890B GC system coupled to an Agilent 5977A Mass Selective Detector (Agilent Technologies, Santa Clara, CA, USA). The TDU conditions were heating from 30°C to 250°C at 60°C·min−1, holding for 10 min at 250°C, and cryo-focusing at −50°C in the CIS4. Following tube desorption, the CIS4 was heated to 300°C at a rate of 12°C·s−1 in splitless mode to transfer the analytes to the GC column (DB-WAX capillary column, 30 m length, 0.25 mm i.d., and 0.25 µm film thickness; Agilent Technologies, Santa Clara, CA, USA). The temperature program of the column oven was set to 40°C for 2 min, 4°C·min−1 up to 180°C, held at 180°C for 5 min, 15°C·min−1 up to 250°C, and held at 250°C for 10 min. The injection, interface, and ion source temperatures were 250°C, 280°C, and 250°C, respectively. Helium was used as the carrier gas. The mass scan range was m/z 30–300 and the electron potential set to electron ionization 70 eV. Compounds were identified with the Wiley 11th/NIST 2017 library search algorithm provided with the GC-MS software and/or comparison of mass spectra with standard compounds and retention indices (Oyama-Okubo and Mikanagi, 2023). Reagents from Toronto Research Chemicals Inc. were used to identify methyl (E, Z)-2,4-decadienoate and methyl (E, E, Z)-2,4,6-decatrienoate.
Sensory assessment of scent compounds.The sensual features of 2–6 fresh flowers of each cultivar were recorded by the authors before and after sampling emitted volatiles.
The sensory features of major scent compounds of each flower were derived by referring to Burdock (2010) and The Good Scents Company Information System (http://www.thegoodscentscompany.com/). Commercially available reagents of identified compounds were evaluated for their odors.
GC-Olfactometry (O)-MS analysis was also performed on a sample of ‘Anne-Marie de Montravel’. GC-MS conditions were the same as above. The flow gas from the column exit was split to the MS and a sniffing port system (ODP3; Gerstel Inc.) with a split ratio of 1:1. The odors of the isolated compounds were assessed by olfaction through the sniffing port.
Composition ratios of volatile compounds in flowers of old Polyantha cultivars (%).
Structure of stink bug pheromone compounds detected from floral scent of ‘Anne-Marie de Montravel’.
Linkage of roses in which stink bug pheromone compounds were detected. Roses in a square: analyzed wild species/cultivars. Roses with white text: wild species/cultivars in which stink bug pheromone compounds were detected. Gray line: parent status is estimated. Dotted line: ancestors several generations ago. HMult; Hybrid Multiflora, Min; Miniature, Pol; Polyantha, T; Tea.
‘Anne-Marie de Montravel’ has a citrus scent with an old, sweet woody odor reminiscent of the smell of old wooden closets. ‘Mignonette’ has a spicy sweetness with an unusual odor, and ‘Pâquerette’ has a sweet spicy scent with a faint unusual odor.
As a result of GC-MS analysis of these old Polyantha cultivars, the major scent components identified were geranyl acetate and eugenol for ‘Anne-Marie de Montravel’, 2-phenylethanol, geraniol and eugenol for ‘Mignonette’, and geranyl acetate and 2-phenylethanol for ‘Pâquerette’. The fatty acid derivatives methyl (E, Z)-2,4-decadienoate (MDD) and methyl (E, E, Z)-2,4,6-decatrienoate (EEZ-MDT) and their isomers (Khrimian, 2005) were detected as characteristic aroma components in these old Pol cultivars. Additionally, four unknown compounds with GC-MS spectral patterns similar to EEZ-MDT were detected.
As a result of GC-O analysis of ‘Anne-Marie de Montravel’, un unusual odor reminiscent of an old wooden closet was detected when the EEZ-MDT, ZEZ-MDT (tentative) and EEE-MDT (tentative) peaks were eluted. In addition, the old wooden closet odor was noticed when the peaks of two unknown compounds (unknown 1 and 2) were eluted. Thus, the unusual odor of ‘Anne-Marie de Montravel’ is thought to be derived from EEZ-MDT and its isomers (MDTs). Comparing the amounts of MDTs based on the peak area of the mass chromatogram, ‘Anne-Marie de Montravel’ had the highest amount, followed by ‘Mignonette’ and ‘Pâquerette’, which were proportional to the intensity of the unusual odor. It is thought that the higher the amounts of MDTs, the stronger the unusual old wooden closet odor.
MDD was identified as the sex pheromone of Nearctic stink bugs (Euschistus spp.) (Aldrich et al., 1991, 1994; Takagi, 1997), and EEZ-MDT was identified as the aggregation pheromone of the brown-winged green bug (Plautia stali) (Sugie et al., 1996). EEZ-MDT is also known to attract the brown marmorated stink bug (Halyomorpha halys) (Tada et al., 2001). Both compounds and their isomers are known as “stink bug pheromones”, and there is a substantial body of research dedicated to preventing stink bug feeding damage to crops (Aldrich et al., 2007; Khrimian et al., 2008; Morrison III et al., 2017; Tillman et al., 2010; Weber et al., 2014, 2020). There is only one report of MDD detection in plants, specifically in enzyme-treated pear extracts (Riu-Aumatell et al., 2004, 2005), and EEZ-MDT has never been detected in plants.
Since stink bug visits are unavoidable in rose gardens, it is possible that MDD and EEZ-MDT are derived from stink bugs. Therefore, we cultivated ‘Anne-Marie de Montravel’ in an environment free of stink bugs (green house of NARO) and collected its scent components. As with the results obtained with flowers collected in the park, MDD, EEZ-MDT and its isomers, as well as unknown EEZ-MDT-like compounds were detected in ‘Anne-Marie de Montravel’ grown in a greenhouse (data not shown). Therefore, it can be said that MDD and EEZ-MDT are emitted from rose flowers. It was previously thought that these compounds were emitted only from insects, but this report reveals for the first time that they are emitted from flowers.
Scent compounds of R. multiflora and derived cultivars (Tables 2 and S3; Fig. 3)
Composition ratios of volatile compounds in flowers of Rosa multiflora and its descendant cultivars (%).
Both plants of R. multiflora analyzed (Echigo and Keisei) had a sweet and spicy scent. The main components identified in both plants were 2-phenylethanol, geranyl acetate, and eugenol.
MDD and MDTs were not detected in R. multiflora (Echigo). Although trace amounts of MDD and MDTs were detected in R. multiflora (Keisei), no unusual odor was detected. Since the amounts of MDD and MDTs in R. multiflora (Keisei) were small compared to three old Pol cultivars, it is likely that they did not affect the fragrance of the flowers.
The detection of MDD and MDTs in R. multiflora (Keisei) scent suggests that R. multiflora can biosynthesize MDD and MDTs. The origin of MDD and MDTs in the three old Pol cultivars is R. multiflora, and it is thought that these cultivars containing large amounts of MDD and MDTs were generated through increased biosynthetic enzyme activity during the breeding process. However, since MDD and MDTs were not detected in R. multiflora (Echigo), it is conceivable that the biosynthetic may have undergone mutations rendering them inactive in Echigo, or that the quantities of these compounds fell below the olfactory detection threshold in Echigo.
‘Crimson Rambler’ (HMult) has a very weak sweet and spicy scent. Most of the identified volatile components of ‘Crimson Rambler’ were hydrocarbons, with ionones, 2-phenylethanol, and eugenol also detected. The sweet and spicy scent is thought to be derived from these components. MDD and MDTs were not detected.
‘Rose-Marie Viaud’ (HMult), a descendant of ‘Crimson Rambler’, has a weak sweet rose-like scent. The scent is thought to be mainly derived from β-citronellol, the main component of the volatile compounds. Additionally, two of EEZ-MDT’s isomers were detected from ‘Rose-Marie Viaud’, but the old wooden closet-like odor was absent.
‘Cécile Brunner’ (Pol), which has the same parentage as ‘Anne-Marie de Montravel’, has a light, sweet rose-like scent. The scent is thought to be derived from the main components, 2-phenylethanol and geraniol. MDD and MDTs were not detected. There is a different in opinion regarding the parentage of this cultivar. According to Sisley (1886), it was R. multiflora × ‘Souvenir d’un Ami’. The large difference in the composition of scent components between ‘Cécile Brunner’ and ‘Anne-Marie de Montravel’ may be due to the different combinations of parents.
‘Clothilde Soupert’ (Pol), has a light, sweet rose-like scent. The scent is thought to come from the main components, 2-phenylethanol and geraniol. MDD and MDTs were not detected. ‘Clothilde Soupert’, also known as ‘Fen Zhuang Lou’, in Chinese, is said to have a spicy scent (Yomogida, 2004), but no spicy scent was detected, and eugenol, a typical component of spicy scents, was not detected. Only trace amounts of methyl eugenol, which has a spicy scent, were detected.
‘Gloire des Polyantha’ (Pol) has a distinctive sweet scent. The main scent components detected were geranyl acetate and geraniol, and MDD and MDTs were not detected. The distinctive scent observed in ‘Gloire des Polyantha’ is believed to result from the combination of eugenol, which imparts a spicy scent, and geranyl acetate, known for its sweet floral-fruity scent.
‘Madame Norbert Levavasseur’ (Pol), has a very weak sweet scent. The main scent component detected was 2-phenylethanol, and MDD and MDTs were not detected. The sweet scent is thought to be caused by 2-phenylethanol.
Both ‘Marie Pavié’ (Pol) and its sport cultivar ‘Marie Daly’ (Pol) have a sweet fruity scent along with a strong old wooden closet-like odor. The main scent components detected were geranyl acetate, 2-phenylethyl acetate, and 2-phenylethanol, MDD and four of MDTs. The sweet fruity scent is thought to be caused by geranyl acetate and 2-phenylethyl acetate, while the old wooden closet-like odor is thought to be caused by MDTs.
R. multiflora ‘Nana’ (Pol), whose parentage is unknown, has a spicy scent and a strong old wooden closet-like odor. The main scent components detected were eugenol, geranyl acetate, MDD and three of MDTs. The spicy scent is thought to be caused by eugenol, and the old wooden closet-like odor is thought to be caused by MDTs.
‘Yvan Misson’ (Pol) has a mild spicy scent. The maternal parent of ‘Jeanny Soupert’ (Pol) was ‘Madame Norbert Levavasseur’ and the paternal parent of ‘Katharina Zeimet’ (Pol) was ‘Marie Pavié’. Approximately 85% of the scent components were hydrocarbons, eugenol and methyleugenol, which are thought to be responsible of the spicy scent. In addition, two of MDTs were detected, but the old wooden closet-like odor was not detected.
‘Gourmet Popcorn’ (Min), a sport cultivar of ‘Popcorn’ (Min), has a sweet scent with an old wooden closet-like odor. ‘Popcorn’ is a cultivar resulting from a cross between ‘Katharina Zeimet’ and ‘Diamond Jewel’(Min) with ‘Crimson Rambler’ also in their ancestral lineage. The main scent components detected were geranyl acetate and 2-phenylethanol, and MDD, EEZ-MDT, as well as four of MDTs. The sweet scent is thought to be caused by geranyl acetate and 2-phenylethanol, and the old wooden closet-like odor is thought to be caused by MDTs.
Threshold Percentage of MDTs that results in the old wooden closet-like odorMDTs were detected in ‘Anne-Marie de Montravel’ (percentage of MDTs in the total emitted scent components; 12.4%), ‘Mignonette’ (3.7%), ‘Pâquerette’ (1.4%), R. multiflora (Keisei) (1.1%), ‘Rose-Marie Viaud’ (2.9%), ‘Marie Pavié’ (7.6%), ‘Marie Daly’ (7.9%), R. multiflora ‘Nana’ (5.8%), ‘Yvan Misson’ (2.8%) and ‘Gourmet Popcorn’ (11.3%). Comparing the amounts of MDTs in the peak area of the mass chromatogram, ‘Anne-Marie de Montravel’ (3,669,328,765) had the highest amount, followed by ‘Marie Daly’ (2,589,519,609), ‘Marie Pavié’ (1,308,444,365), ‘Gourmet Popcorn’ (667,625,337), ‘Mignonette’ (378,766,121), R. multiflora ‘Nana’ (294,190,301), ‘Pâquerette’ (144,492,680), R. multiflora (Keisei) (91,306,611), ‘Yvan Misson’ (65,224,122) and ‘Rose-Marie Viaud’ (40,963,286). Among these cultivars, the old wooden closet-like odor was noticed in ‘Anne-Marie de Montravel’, ‘Marie Pavié’, ‘Marie Daly’, R. multiflora ‘Nana’ and ‘Gourmet Popcorn’.
The compounds responsible for the unpleasant odor in Rosa foetida were 2,4-decadienal and 2,4-decadienol, which have a low threshold of detection, and the unpleasant odor was noticed at amount less than 1% (Oyama-Okubo and Mikanagi, 2023). Although the threshold value for MDTs is unknown, no odor was detected by GC-O analysis for EEZ-MDT or its isomer components with a content of less than 1%. Additionally, the unusual odor of R. multiflora ‘Nana’ was perceived to be stronger than that of ‘Mignonette’, which contains higher amounts of MDTs. For MDTs to be perceived as an old wooden closet-like odor, it is thought that the proportion contained in the total scent components has a large effect. If the scent component of roses contains at least 5.8% MDTs, it is believed that the old wooden closet-like odor will become noticeable.
Biosynthesis of MDD and MDT in roses (Fig. 4)
Putative biosynthetic pathways of aliphatic scent compounds in the genus Rosa.
MDD is biosynthesized by methylation of carboxylic acids such as 2,4-decadienoic acid (DDA) and MDT is biosynthesized by methylation of 2,4,6-decatrienoic acid (DTA). Both DDA and DTA have been identified only from Euphorbia species; DDA has been detected in the seed oil of Sapium sebiferum (Devine, 1950), and DTA as a mixture of geometric isomers esterified with diterpenols and triterpenols, has been detected in the latex of E. pulcherrima Willd. (Warnaar, 1977) and E. lathyris (Warnaar, 1981).
There are no reports on the biosynthesis of DDA and DTA. Based on their structures, it is possible that DDA is generated by oxidation of the aldehyde group of 2,4-decadienal (2,4-DA) and DTA by oxidation of the aldehyde group of 2,4,6-decatrienal (2,4,6-DTA). In the scent of R. foetida, 2,4-DA has been identified together with 2,4-decadienol and (z)-jasmone (Oyama-Okubo and Mikanagi, 2023). The 2,4-DA biosynthesis genes in R. foetida may also be present in other wild species of the genus Rosa, such as R. multiflora. 2,4,6-DTA that has not been detected in the genus Rosa, but it has been detected as a component produced when wheat flour is heated together with 2,4-D. (Dach and Schieberle, 2021). 2,4,6-DTA, like 2,4-DA, may have been produced from linoleic acid or α-linolenic acid.
This is the first report of these compounds being detected in the scent of not only the genus Rosa, but also in the plant kingdom in general.
MDD and MDT, which are known as stink bug pheromones, were identified as the components that give a distinctive, unpleasant odor to rose fragrances. As mentioned above, MDT is often used as a pheromone agent in research on stink bugs, and it is well established that it attracts stink bugs. However, in rose gardens, stink bugs did not appear to be particularly attracted to roses containing MDD or MDT in their scent, such as the ‘Anne-Marie de Montravel’ cultivar. There may be other components in the rose scent containing MDD and MDT which have a repellent effect on stink bugs.
The presence of MDT gives roses the unusual scent, reminiscent of an old wooden closet. On the other hand, depending on the balance of scent components, it is possible to create a new blend of rose scents with a small amount of the old wooden closet-like odor as a kind of secret ingredient.
We have also found the old wooden closet-like odor in cultivars which have no relationship with R. multiflora, Hybrid Multiflora or Polyantha roses. In future studies, it will be interesting to analyze the scent components of these cultivars, to look for precursor fatty acids and clarify the biosynthetic pathways of MDD and MDT and their distribution in the genus Rosa.
We thank Mr. Takashi Kawai (Yokohama English Garden), Mr. Shinichiro Iritani (Keisei Rose Garden), Mr. Katsuhiko Maebara (The City of Sakura Rose Garden), Ms. Junko Sakurai (Echigo Hillside Park), Mr. Masanobu Tsuji (Hamadera Park Rose Garden) and Ms. Yuki Himeno (Himeno Rose Nursery) for providing plant materials.
