Both biological properties and physicochemical properties, that is, biosynthetic activity of plants and vapor pressure of each compound, determine emission amounts of floral scents. Temperature influences both factors. Furthermore, the biological activity sometimes shows a time-course change. This leads to the following important knowledge in understanding floral scent property: 1) Composition ratio of floral scent compounds emitted from a flower is drastically different from one contained in the flower tissues. 2) Floral scent components should be evaluated considering time-course change as well as change caused by temperature.

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Floral scent is one of the survival strategies that flowers use to attract pollinators, and flowers of wild species change their scent to suit the pollinators they are attracting. On the other hand, there are many horticultural cultivars of flowers cultivated by humans, such as roses and lilies, which have scents that are not found in wild species due to artificial crossbreeding. Through human hands, floral scent has become more complex and diverse. Here, I will look at the scents of roses, lilies, and lisianthus to explain the diversity of flower scents.

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Floral scents are among the most critical commercial traits of floricultural plants, along with flower color, shape, and longevity (vase life). However, floral scent traits were often overlooked in breeding programs mainly because perception assessments were generally limited to sensory evaluation by the human nose. The amounts and kinds of odor chemicals emitted from flowers can be estimated precisely using gas chromatography / mass spectrometry nowadays, and thus breeding of floricultural plants exhibiting fine fragrances is enhanced now and will be more active in the future. Improvement of floral scent characteristics is also active in lilies, one of the major floricultural plants worldwide. Interspecific hybridization is the principal method to breed lily cultivars. Cultivated lilies are classified in several hybrid groups, e.g., Asiatic, Oriental, Longiflorum, Trumpet, LA, and OT hybrids, according to their parental wild lily species used for the hybridization. Characteristics of floral scents vary depending on the hybrid groups, e.g., the fragrance in Oriental hybrid lilies is often strong and sweet, that in OT hybrid lilies is fresh and sweet due to the emission of eucalyptol, but Asiatic hybrid lilies and LA hybrid lilies have little or no scent. Thus, strategies to select cultivars with fine fragrance vary depending on the hybrid groups. The floral scent characteristics and the strategies to improve them are shown in each of the hybrid groups in this article.

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Edible flowers not only make colourful dishes more attractive, but also have the potential to impart unique flavours and enhance taste, and in recent years flowers have become increasingly popular as fresh vegetables around the world. To date, there have been some positive results on the functionality of edible flowers and their use as nutritional supplements, but few reports have investigated changes in their aroma due to cultivation conditions and processing of edible flowers. In this paper, we introduce a study on the effects of drying of edible flowers, different growing districts and harvesting times on the functional properties and aroma in rose petals.
When four edible rose cultivars were dried using different drying methods, the total polyphenolic content and antioxidant activity of ‘Mariah’ and ‘Yves Piaget’ were almost equal to those of fresh petals in moisture absorption and 55°C drying plots. The total polyphenolic content of both cultivars in the moisture absorption drying plots remained almost constant from immediately after drying to 60 days of storage. Total carotenoid content was highest in fresh flower petals of ‘New Birdie’ and decreased significantly in all drying treatments, further decreasing with storage days. The content of aroma compounds in fresh flower petals was higher in ‘Kana Rose’ and ‘Yves Piaget’, but significantly decreased in all four cultivars in all drying treatments. Therefore, it is clear that during drying of flower petals of the four cultivars tested in this study it is difficult to retain the fragrance, although moisture absorption drying is useful for retaining polyphenolics and carotenoids.
When edible rose ‘Yves Piaget’ was grown at different districts, differences in the aroma component content were observed between districts. The relationship between the differences in aroma component content at different growing districts and the temperature at the growing districts was investigated, and a strong negative correlation was found between the diurnal variation and total aroma component content. It was therefore inferred that a decrease in the diurnal variation leads to an increase in the aroma component content.
When edible roses ‘Dramatic Rain’ were harvested at different times of the year, the ‘Dramatic Rain’ aroma varied between rose-like and floral-like aromas, suggesting that the aroma impression varied depending on the harvest time. In this study, flowers harvested in October were judged to have the most floral and intense fragrance.
These results indicate that the aroma of edible roses varies depending on the processing and cultivation method. Therefore, it is necessary to select the harvesting time, production districts and processing methods according to the purpose of use.

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Floral scents are among the key adaptive traits which facilitate plants' reproductive success through guiding specific pollinators to flowers, and their role as the olfactory cue for pollinators has likely been maintained and evolved since the origin of insect pollination in the Mesozoic gymnosperms. Because the component compounds of floral scents are highly diverse, they function as complex and specific signals for pollinators, thus the evolutionary changes of the individual components of floral scents can lead to plant speciation through switching of pollinators. This means that the floral scent traits, targeted by natural selection, can act as the driver of plant diversification. To examine this hypothesis, I highlight the genus Asimitellaria (Saxifragaceae) which consists of 14 species endemic to Japan and Taiwan, indicating that its diversification has been centered in the Japanese Archipelago. In Asimitellaria, the principal pollinators are a limited species of fungus gnats (Mycetophilidae), and our research group demonstrated that the multiple pollinator switches between long-tongued fungus gnats and short-tongued fungus gnats have taken place in association with the loss or gain of the floral volatile containing lilac aldehydes. Ongoing research has identified the candidate genes responsible for the floral scent changes, and the examination of whether these genes are the “speciation genes” are underway.

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Lytic phages specifically infect and lyse a host bacterial cell, and are being investigated as a treatment for bacterial infections. In addition, attempts are being made to apply phages to reduce contamination of foodborne pathogens in food and to control plant pathogens that damage agricultural produce such as rice and tomatoes. The biggest problem with applying phages in bacterial control is the development of phage resistance in the host bacterial population. This review outlines the mechanism of phage resistance in bacteria, isolation and application of phages controlling foodborne pathogens and food spoilage bacteria, optimization of a phage cocktail, and the combined effects of phages and food additives or natural substances for the control of phage-resistant bacteria. In the isolation of Clostridium perfringens-specific phages and application of a phage cocktail, a combination of four different phages that had the strongest bacteriolytic activity and could suppress the growth of resistant bacterial populations was investigated. In curry roux, viable C. perfringens count was significantly reduced to below the detection limit at 24℃, and the growth of resistant cells was inhibited for up to 48 h. The combination of EDTA and phages was also shown to effectively inhibit the regrowth of phage-resistant populations of Campylobacter, Escherichia coli, Salmonella, and Listeria. The combination of nisin and phages was effective in killing planktonic and biofilm cells of Staphylococcus aureus and delayed the regrowth of phage-resistant populations. Furthermore, the combination of cinnamon oil and phage was effective against Listeria, reducing the viable count of Listeria in milk at 4℃ by more than 4 logs and inhibiting the regrowth of resistant populations. Phages can be produced at low cost, so they provide an economical method for controlling food poisoning bacteria. Phage application is effective in preventing food poisoning, in reducing food waste, extending the shelf life of high-quality processed foods, and is expected to contribute to the achievement of the United Nations Sustainable Development Goals. It is expected that original phage preparations for controlling foodborne pathogens will be approved as food additives in Japan.

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Plants have a wide range of volatile compounds which are required for biological interactions with various organisms. Plant volatile compounds are often stored in plants as glycosides (GBV; glycosidically bound volatiles). A group of glycosyltransferases called plant secondary product glycosyltransferases (PSPGs) are responsible for GBV production in plants. One of the characteristic volatile compounds of strawberry, 4-hydroxy-2,5-dimethyl-3(2H)-furanone (HDMF), exists not only as an aglycon but also in various modified forms. Among them, the glucoside (HDMF 4-O-glucoside) is a well-known compound. To identify the HDMF glycosyltransferases in strawberries, we attempted a comprehensive gene cloning of novel PSPG genes expressed in strawberry receptacles. We found only UGT85K16, isolated as a homolog of UGT85K14, an HDMF glycosyltransferase from grapes. We determined the kinetic parameters of UGT85K16 and compared its catalytic efficiency, indicating that UGT85K16 has a high substrate specificity for HDMF. Gene expression analysis and the accumulation of HDMF glucosides showed a correlation between the expression of UGT85K16 and the accumulation of HDMF glucosides. These results suggest that UGT85K16 may play a key role in HDMF glycosylation. If the functions of UGT85K16 and other PSPGs in strawberries are clarified, the mechanism and physiological role of HDMF glycosylation and regulation of HDMF release could be elucidated in future investigations.

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[in Japanese]

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[in Japanese]

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The “International Symposium in Okinawa, 2023, on Ciguatera and Related Marine Biotoxins” took part in the Okinawa Convention Center, Okinawa, Japan, on November 13-14, 2023. It was held as a post-symposium of the 20th International Conference on Harmful Algae (ICHA2023, Hiroshima, November 5-10, 2023).
The symposium aimed to bring together the latest research on the chemistry, analysis, epidemiology, toxicology, and etiology of ciguatera, ciguatoxin, and other marine biotoxins (e.g., maitotoxin, gambier acid, gambier, palytoxin, okadaic acid, azaspiracid saxitoxin, and tetrodotoxin).
The symposium consisted of invited lectures, presentations from the Asia-Pacific region (Fiji and the Philippines), short speeches by young scientists, poster presentations, and presentations by Okinawan high school students. Eight speakers from French Polynesia, New Zealand, France, Canada, Spain, and Japan were invited, and they presented their latest observations on studies of ciguatera and other marine biotoxins and related fields. Forty-two poster presentations were provided, including those covering chemistry, analytical science, toxicology, and epidemiology. The symposium was attended by approximately 120 people from more than ten countries and regions, making it a very productive event. The participants also enjoyed visiting and staying in Okinawa, where Prof. Hashimoto's team started studying ciguatera and other marine biotoxins in the 1960s. These studies are based on Yasumoto's field surveys in Okinawa, who participated in Hashimoto's research team as a graduate student, and he played a key role.
The organizing committee recognized the symposium as more than just a gathering of researchers. It was a platform that fostered collaboration among participants, providing young researchers in Japan, especially those from remote islands, with the opportunity to experience cutting-edge research activities.

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