Anthocyanin O-methyltransferase (OMT) is one of the key enzymes for anthocyanin modification and flower pigmentation. We previously bred a novel red-purple-flowered fragrant cyclamen (KMrp) from the purple-flowered fragrant cyclamen 'Kaori-no-mai' (KM) by ion-beam irradiation. Since the major anthocyanins in KMrp and KM petals were delphinidin 3,5-diglucoside and malvidin 3,5-diglucoside, respectively, inactivation of a methylation step in the anthocyanin biosynthetic pathway was indicated in KMrp. We isolated and compared OMT genes expressed in KM and KMrp petals. RT-PCR analysis revealed that CkmOMT2 was expressed in the petals of KM but not in KMrp. Three additional CkmOMTs with identical sequences were expressed in petals of both KM and KMrp. Genomic PCR analysis revealed that CkmOMT2 was not amplified from the KMrp genome, indicating that ion-beam irradiation caused a loss of the entire CkmOMT2 region in KMrp. In vitro enzyme assay demonstrated that CkmOMT2 catalyzes the 3' or 3',5' O-methylation of the B-ring of anthocyanin substrates. These results suggest that CkmOMT2 is functional for anthocyanin methylation, and defective expression of CkmOMT2 is responsible for changes in anthocyanin composition and flower coloration in KMrp.

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Abstracte fragrant cyclamens 'Uruwashi-no-kaori' (UR), 'Kaori-no-mai' (KM), 'Kokou-no-kaori' (KO) were bred from amphidiploids that were derived by chromosome doubling of the hybrid among Cyclamen persicum 'Strauss', 'Pure White' and fragrant wild species of C. purpurascens. Amphidiploid of GBCP was produced by chromosome doubling of the hybrid between C. persicum 'Golden Boy' and fragrant wild species of C. purpurascens. In order to create novel ower colors, mutation breeding with carbon-ion-beam irradiation was carried out using amphidiploids of UR, KM and KO as well as dihaploids of UR, KM and GBCP. Immature petals or etiolated petioles of the amphidiploids and dihaploids were irradiated, and plant tissue culture techniques were used to produce material for additional investigations. Furthermore, the stepwise improvement of ower color was achieved by irradiating 'ion3', which had been derived from dihaploid of UR by ion-beam irradiation. e mutants thus obtained were evaluated for breeding new cultivars of fragrant cyclamens. e tissues were then analyzed in terms of their avonoid pigment content and their related genes. Key words:Flower pigment, fragrant cyclamen, ion-beam, mutation, tissue culture.The genus Cyclamen, family Myrsinaceae, includes 22 species. All species of Cyclamen form a tuber and consistently propagate by seed, but never propagate by natural splitting (Grey-Wilson 2002). Ornamental cyclamen cultivars, highly popular pot plants in several countries, have been developed through the crossing of selected natural mutants of wild C. persicum (2n=2x=48). Flowers of C. persicum-derived cultivars may have a purple, pink, red, pale yellow or white 'slip', with an 'eye'; occasionally, the slip is pale yellow, pale pink or white and there is no 'eye'. 'Eye' refers to the bases of the petals colored deep purple and 'slip' refers to the other, non-eye parts of the petal, of various colors (Figure 1). Moreover, these flowers emit woody-or powdery-like scent, which has been expected to improve. In contrast, C. purpurascens (2n=2x=34) has small owers that consist of a purple slip and a deep purple eye, that emit a sweet fragrance, i.e. a rose-, hyacinth-or lily of the valley-like fragrance ( Figure 1A) (Grey-Wilson 2002;Ishizaka et al. 2002). The ornamental value of the cultivars of C. persicum would be enhanced by the introduction of fragrance properties of C. purpurascens.However, C. purpurascens has been neither improved as a major commercial cultivar nor used as breeding material.In earlier work, an allodiploid (2n=2x=41) was produced by the crossing of C. persicum cultivars (2n=2x=48) and C. purpurascens (2n=2x=34) through ovule culture techniques for rescuing abortive hybrid embryos, although all the allodiploids were sterile (Ishizaka and Uematsu 1995). In our subsequent study, however, fertile allotetraploids (amphidiploid, 2n=4x=82) were successfully produced by inducing chromosome doubling with in vitro colchicine treatment of the hybrid ovules. Consequently, two types of fertile amphidiploid plant...

Photosynthetic characteristics measured with the leaves of 'Weymouth' highbush blueberry (Vaccinium corymbosum L.) and 'Tifblue' rabbiteye blueberry (V. ashei Reade) in phytotron were compared with regard to their responses to light intensity (0-2,000 µmol・m −2 ・s −1 ) and temperature (15-35°C). As temperature increased, photosynthetic rates of both cultivars increased.Photosynthetic rates of 'Weymouth' were higher than those of 'Tifblue' under low temperature conditions (15-20°C). However, there was no difference in photosynthetic rates measured under high temperature conditions (25-35°C), but 'Weymouth' showed higher transpiration rates and lower water use efficiencies (WUE) than 'Tifblue'. Furthermore, photosynthetic characteristics of 'Blueray' highbush blueberry under high temperature conditions (28 and 35°C) were similar to those of 'Weymouth' under high temperature conditions. These findings show that photosynthetic characteristics of leaves could be related to the suitability of highbush blueberries to cool conditions, and to the heat tolerance and drought resistance of rabbiteye blueberries. WUE values measured at high temperature >35°C and high light intensity >1,000 µmol・m −2 ・s −1 could be helpful as indices for evaluating and selecting blueberry plants with heat tolerance. Transpiration rates increased at high temperature and high light intensity, which suggested that shading in summer to control light intensity under 1,000 µmol ・m

This study investigated the changes in leaf water potential (Ψ L ) and photosynthetic rate (Pn) of cropping and non-cropping blueberry plants grown under drought and re-watering conditions. Nine-year-old 'Tifblue' plants grown in a pot were used. When plants grown under drought conditions, Ψ L and Pn of leaves decreased as soil water content decreased. Pn decreased to near zero when Ψ L was approximately -3.5 MPa and soil water content was approximately 8%. Under that condition, all fruits and some shoots wilted and some fruits dropped. Pn of cropping plants decreased more rapidly than that of non-cropping plants, under drought conditions. After re-watering, Ψ L and Pn of plants grown under drought conditions were increased and then these values reached half the level of plants grown under well-watered conditions. The rate of increase in Pn in cropping plants was slower than that in non-cropping plants under drought conditions. The values of stomatal conductance and transpiration rate showed a tendency similar to that of Pn. These results showed that the critical point of Ψ L for recovering plant vigor was less than -3~-3.5 MPa. Furthermore, drought stress was promoted by fruit loading.