Minoru Sawano

Effects of bud scales and gibberellins on dormancy of in vitro cultured Japanese pear leaf buds

Abstract Leaf buds of Japanese pear were collected in early June and early November and regarded as summer and winter dormant buds, respectively. Bud explants with and without scales were prepared from each of them, and cultured in vitro for 75 days at 25°C with 14 h photoperiod, on a medium either without growth regulators, or supplied with BA and GAs (GA 3 and GA 4+7 ), singly or in combination. When either BA or GA 4+7 was contained in the medium, bud expansion occurred. Thereafter, summer dormant buds grew into shoots in the presence of BA, while winter dormant buds, although they swelled profusely, remained in a rosette. In the presence of BA, GA 4+7 markedly stimulated shoot elongation of summer dormant buds, but GA 3 did not. In winter dormant buds, GA 4+7 not only failed to stimulate shoot elongation, but also interfered with the BA-induced swelling described above. The presence of bud scales delayed expansion of summer dormant buds, while it had little effect on winter dormant buds. The delaying effect of scales on expansion of summer buds was effectively removed by application of GA 4+7 to the medium.

Determination of indole-3-acetic acid and abscisic acid in Japanese chestnuts by column chromatography on sephadex G-10 and reversed-phase high-performance liquid chromatography

Abstract A method for the separation and quantification of indole-3-acetic acid and abscisic acid in Japanese chestnuts has been developed by use of Sephadex G-10 column chromatography and a reversed-phase high-performance liquid chromatography (HPLC). For the first purification step, the plant hormones are extracted with methanol—water (80:20) then eluted as individual hormone fractions from a Sephadex column. The final purification was performed on a reverse phase (LiChrosorb RP-18, 5 μm), eluted with a linear gradient of 10–50% acetonitrile in 1% glacial acetic acid. The column effluent is monitored at 254 nm. This technique has been used effectively to analyze plant hormones in biological samples.