[in Japanese]

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When plants begin to grow, they cannot move about, so in order to adapt to different environments they have acquired various strategies during the process of their evolution. Plants require particularly ingenious survival strategies in order to have mutually-beneficial symbiotic relationships with organisms such as microbes, insects, and other plants. Recently, it has been revealed that plants employ chemical communication as a strategy, that is, they use chemical substances to transmit information to partners. These chemicals contain substances that are passively accumulated in plant bodies, such as phytoalexins, and those that are aggressively dispersed outside of plants, such as allelochemicals. Among the main chemical substances are terpenes and volatile oxylipins. Research is being conducted on the mechanisms by which these chemical substances are received by plants.

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Capabilities of organisms and their roles can be viewed from two aspects : social relation for the maintenance of ontogeny and social relation for the maintenance of phylogeny. Chemical communication capabilities of organisms and their roles can be seen in a similar way. Because higher plants are sessile organisms, they utilize physical phenomena such as wind and water, and organisms such as insects, birds, or mammals for their mating and dispersal of seeds to maintain their lineage. Their form of evolution has been unique and different from that of animals. Their functions for mating include perfume, flowering season, flower form, flower color, nectar ; the functions for dispersal are perfume, fruit form, sarcocarp, and elaiosome.
Betula, a relatively new lineage of plant, utilizes anemophily and anemochory for its mating and dispersal of seeds. Since the plants of this genus synchronize their flushing and flowering using fragrance, the utilization of anemophily for chemical communication by plants can be judged as relatively new.
Plants (consumer) are inevitably prey for animals. Therefore, plants have evolved protective abilities to maintain ontogeny. To protect their leaves from defoliators either chemically or physically, plants have evolved poisons such as tannin, alkaloid, and terpene. When defoliators chew the leaves of Betula platyphylla, leaf alcohol (cis-3-hexen-1-ol), which is a stabilized alcoholic substance, is biosynthesized from linolenic acid, one of the constituents of the leaf. When dispersed in the air, leaf alcohol effects as an ecomone. Leaf alcohol is the ecomone of Betula, which induces other leaves to produce antifeedant, 3,4′-Dihydroxypropiophenone-3-β-D-glucopyranoside (DHP-Glu.) ; it acts as ecohormone in the other leaves of the same organism, and as a pheromone in the leaves of other individual organisms of the same species, and as allelochemics in the leaves of other species. The term ecohormone is established for chemical messages between leaves of a individual. If newborn hatchlings eat a leaf that contains large amounts of phenol (DHP-Glu.), almost all of them will die. Thus, leaves keep defoliators from proliferating. Leaf alcohol can be said to be a common semiochemical in all plants to protect themselves from defoliators.

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We have developed a new bioassay called Dish Pack Method for analyzing volatile allelochemicals. In this method, leaves of plants were put into one of the holes in a 6-well-multi-dish. It is possible to analyze the internal volatile gas collected from the hole with gas-tight-syringe through the septum set up on the holes. By using this method, it was found that Spider flower (Cleome spinosa) contained strong volatile allelochemicals : methyl isothiocyanate (MITC). MITC was one of the strongest natural volatile allelochemicals. Hairy vetch (Vicia villosa Roth) is also allelopathic in the field and we had newly isolated cyanamide as allelochemicals with volatile nature. Yukiyanagi (Spirae thunbergii Sieb.) is a Japanese native tree with allelopathic activity by its fallen leaves. We had isolated cis-cinnamic acid and its derivatives as new allelochemicals. Plant growth inhibitory activity of cis-cinnamic acid is 1000 times stronger than trans-cinnamic acid, and might be new plant hormone.

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Green leaf volatiles consist of carbon six (C6) aldehydes, alcohols, and acetates. They can be commonly found in most terrestrial plants. They are important flavor compounds in various kinds of foods, also, it has been reported that GLVs have an anti-stress effect in humans. Recent studies suggest that GLVs are involved in establishing an ecosystem surrounding a plant. C6-aldehydes are reactive compounds, and protect plants from invasion of the other organisms. Insects developed a very sensitive sensory system to perceive GLVs, with which they can get higher benefit for their survival. GLVs are also involved in a tritrophic system to recruit an enemy of the herbivores. Furthermore, even plants are assumed to perceive GLVs emitted from the neighboring plants in order to cope with prospective attack by herbivores or pathogens.

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In this study, effects of odor description (positive/neutral/negative) on various cardiovascular responses, as well as subjective responses such as odor perceived intensity and pleasantness were examined. The odor used was anise seed oil, unfamiliar odor to the Japanese people. This study was conducted in accordance with the Declaration of Helsinki and the ethical committee rules of Bunkyo Gakuin University. The effects of odor description on the subjective variables such as pleasantness were significant, which is consistent with our previous findings. In addition, the effect of odor description was also significant in part of cardiovascular responses. To be precise, those who were given a negative description on anise seed oil (the negative description group) perceived the odor more unpleasant as compared with participants given a positive description (the positive description group), and the systolic blood pressure (SBP) and the diastolic blood pressure (DBP) of the negative description group were also significantly higher than those of the positive group. These results suggest that a preconception on the odor manipulated by the description influenced odor perception/cognition, resulting in significant effects on cardiovascular responses as well as subjective responses.

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