Karyotype analysis was performed on spore calli of Osmunda japonica on MS media containing 2, 4-D and kinetin in order to clear up the cytogenetical behavior of callus cells from the haploid cells of a fern.
The spore calli showed a fair stability in haploid chromosome number (n=22). However, these calli showed a remarkable variation in karyotype as follows. The normal karyotype corresponding to that of the sopre donor was observed only in a few callus cells. The other karyotypes in many spore calli were multiple, and not systematically consolidated. These karyomorphological aspects were concluded that gross rearrangements of chromosome structures with maintaining a fair stability in haploid chromosome number are associated with spore cultures of O. japonica as a nuclear response to callus induction and to established culture condition.

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Fusaric acid-resistant regenerants were selected in vitro by using the tissue culture system of tomato. The callus tissues were induced from the leaf explants of tomato and subcultured in a MS (0.01mg/l IAA and 0.1mg/l BAP) medium. After incubation for two weeks, a lot of green spots were produced in the callus tissues. The tissues were cut into small callus clumps so as to contain one green spot and transferred to a MS medium (0.1mg/l IAA and 1.0mg/l BAP) containing 50μg/ml fusaric acid. Fusaric acid-resistant regenerants were effectively developed from enlarged green spots and rooted in a hormone-free MS medium. For examining the resistance in regenerants at one month after transplantation to soil, their upper branches were cut and dipped in the solution containing 300μg/ml fusaric acid. In the branches of regenerants grown in the absence of fusaric acid, the resistance was fully maintained and expressed.

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The calli were induced from the pistils of saffron. MS, 1/2 MS, and NN medium with BA and NAA at 1mg/l each were the most effective for the induction and growth of the calli. The calli produced crocin, crocetin-di (monoglucosyl-diglucosyl) ester and crocetin-di (monoglucosyl) ester. The calli producing those pigments have been maintained for more than two years under dark conditions.

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Pollen calluses and plants were obtained in rice (Oryza sativa L.) through pollen culture without preculture of anthers. The spikes were pretreated at 10°C for 10-30 days. Isolated pollen grains at the late uninucleate stage were cultured in a medium consisting of one eighth to three eighths of the nutrient constituents of N₆ supplemented with 1% sucrose, 1% glucose, 0.1% yeast extract, 0.1% casein hydrolysate, and 10^-5M 2, 4-dichlorophenoxyacetic acid. After 11 days of culture, small calluses were induced from the pollen grains. To regenerate plants, viable calluses were transferred from the liquid medium onto the agar media for differentiation. All the regenerated plantlets, including haploid ones, were planted in paddy fields to obtain mature plants.

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Six types of cultured tissues at various stages of differentiation were induced from rhizome segments of Wasabia japonica Matsum. (Japanese name: wa-sa-bi); NC callus, rootlets, embryoids, differentiated tissues I and II, and plantlets. Myrosinase activity was detected at all stages of differentiation, but sinigrin could not be detected from NC callus, rootlets and embryoids, so that pungency could be felt from differentiated tissues I, II and plantlets. It is supposed that the process of differentiation stages (the increase of the rhizome weight) is parallel to the sinigrin content in the tissues.

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[in Japanese]

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[in Japanese]

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The presence and levels of zeatin, ribosylzeatin, 9-glucosylzeatin ([9G] Z), N⁶-isopentenyladenosine and 9-glucosyl-N⁶-isopentenyladenine ([9G] iP) were determined in calluses of sweet-potato plant (Ipomoea batatas Lam cv. kohkei No 14) and its wild species (I. batatas 13-1 and I trifida Don) by mass spectrometry using deuterium-labeled standards. The levels of [9G]iP and [9G]Z were, respectively, 3.6μg and 2.7μg per 100g fw of the callus derived from the tuberous root of sweetpotato.

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