Tomoo Maeda

Confirmation of Fructans biosynthesized in vitro from [1-13C]glucose in asparagus tissues using MALDI-TOF MS and ESI-MS.

Accumulation of Fructans was confirmed in asparagus tissues that had been cultured for 2 days on media supplemented with glucose. It is very common that Fructans are biosynthesized from sucrose. We hypothesized however that Fructans could also be biosynthesized from glucose. Stem tissues of in vitro-cultured asparagus were subcultured for 72 h on a medium containing 0.5M of [1-(13)C]glucose. A medium containing 0.5M of normal ((12)C) glucose was used as control. Carbohydrates were extracted from the tissues and analyzed using HPLC, MALDI-TOF MS and ESI-MS. HPLC results indicated that the accumulation of short-chain Fructans was similar in both (13)C-labelled and control samples. Short-chain Fructans of DP=3-7 were detected using MALDI-TOF MS. The molecular mass of each oligomer in the (13)C-labelled sample was higher than the mass of the natural sample by 1 m/z unit per sugar moiety. The results of ESI-MS on the HPLC fractions of neokestose and 1-kestose showed that these oligomers (DP=3) were biosynthesized from exogenous glucose added to the medium. We conclude that not only exogenous sucrose but glucose can induce Fructan biosynthesis; fructans of both inulin type and inulin neoseries are also biosynthesized from glucose accumulated in asparagus tissues; the glucose molecules (or its metabolic products) were incorporated into Fructans as structural monomers.

Effects of Various Asparagus Production Methods on Rutin and Protodioscin Contents in Spears and Cladophylls

The purpose of this study was to clarify the relationship between various cultivation conditions and the amounts of the rutin (RT) and protodioscin (PD) in asparagus spears. Green and white spears were grown in open culture and under two different blanching conditions. Although RT was detected only in the green spears, PD was detected mainly in white spears produced by covering with soil. The RT and PD contents of cladophylls grown in an open field and in a closed cultivation system were also investigated, and the closed system resulted in cladophylls with low RT and high PD, unlike the open field.

Promotion of flowering by photoperiod treatment in six strawberry (Fragaria × ananassa Duch.) cultivars with different everbearing Patterns

Summary The effects of different photoperiod treatments (12, 16, 20, or 24 h) and their duration (1, 2, 3, or 4 weeks) on the percentage of flowering plants and the number of inflorescences were investigated in the Summer in everbearing (EB) strawberry (Fragaria _ ananassa Duch.) cultivars with various EB strengths in a field in northern Japan. For ‘Tochihitomi’, a strong EB cultivar, inflorescences emerged in all control plants grown under the natural photoperiod ( 14.5 h), and the number of inflorescences was not affected by any photoperiod treatment. In cultivars of intermediate EB strength (i.e., ‘Summer-drop’, ‘Summer-tiara’, ‘Miyazaki-natsuharuka’, and ‘Summer-fairy’), flowering was < 100% under a 12-h photoperiod.The number of inflorescences was higher under the 24-h photoperiod than in control plants, with the effect of the duration of the photoperiod dependent on cultivar. For ‘Natsuakari’, a weak EB, 0 - 20% of plants flowered under the 12-h photoperiod, and 0% under the natural photoperiod. However, flower buds were induced in all plants treated with the 16-h or 20-h photoperiods for 2 weeks, or with the 24-h photoperiod for 1 week. Furthermore, the 16-h (2 weeks) and 20-h and 24-h (1 week) photoperiod treatments induced significantly more inflorescences than in control plants. Although the characteristics of flowering of EB strawberry plants differed between cultivars, we suggest that flowering can be promoted by a 24-h photoperiod applied for 1 - 4 weeks in cultivars of weak or intermediate EB strength.

Rapid analysis of fructans and comparison of fructan profiles in several different types of asparagus storage roots using MALDI-TOF MS

Summary Appropriate conditions for analysing fructans in the storage roots of field-grown asparagus using matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) were investigated. High resolution and ionisation were achieved when lyophilised and ground storage root powders were extracted twice with 1.0 ml distilled and deionised hot water (90°C), supplemented with 1.0 ml of 100% (v/v) ethanol, concentrated to approx. 1.0 ml, and mixed with 10 g l–1 2,5-dihydroxybenzoic acid (DHB) at 1:1 (v/v) before loading on a sample slide for MALDI-TOF MS, which was performed in the linear positive ion mode at a laser intensity of 15 kV. The mass spectral profiles showed that the degree of polymerisation (DP) of fructans ranged from three-to-21 in storage roots collected in the Winter.When different amounts of -cyclodextrin were added to each sample, a linear positive relationship was observed between the amount of -cyclodextrin and the relative positive ion intensity. With -cyclodextrin as an internal standard, fructan profiles were compared between Summer- and Winter-collected asparagus storage root samples. Furthermore, the fructan profiles of three different types of storage root of different colours (i.e., milky-white, yellow, or dark-brown) were also examined. Fructan contents were always higher in the Winter-collected samples than in those collected in the Summer, regardless of the DP. However, samples from the different coloured roots showed variable fructan profiles, depending on the DP. These results indicate that fructan analysis using MALDI-TOF MS would be useful for examining the dynamics of carbohydrate metabolism in asparagus storage roots because of its high degree of accuracy and its simplicity.