Buckwheat (Fagopyrum esculentum Moench.) is an Al-accumulating plant, but the internal mechanism(s) of detoxification of Al is not fully understood. We investigated the subcellular localization of Al in the leaves of this plant (cv. Jianxi) by directly isolating protoplasts and vacuoles. Pure protoplasts and vacuoles from the leaves of buckwheat, grown hydroponically in Al solution, were obtained based on light-microscopic observation and the activities of marker enzymes of cytosol and vacuoles. More than 80% of total Al in the leaves was present in the protoplasts, and was identified as an Al-oxalate complex (1:3 ratio) by (27)Al-nuclear magnetic resonance. Oxalate and Al in the protoplasts was localized in the vacuoles. These results suggest that internal detoxification of Al in the buckwheat leaves is achieved by both complexation with oxalate and sequestration into vacuoles.

We developed a new method for culture of isolated pollen. Using highly homogeneous populations of immature pollen grains of Nicotiana tabacum L. prepared by means of Percoll density gradient centrifugation, we could direct their developmental pathway by regulating certain culture conditions. When the pollen population was cultured in basal medium with glutamine, most pollen grains underwent normal maturation. On the other hand, when first cultured in basal medium without glutamine, most pollen grains did not mature but after transfer to medium with glutamine and sucrose began to divide. This method for inducing pollen cell division was possible only with midbinucleate pollen grains which are characterized by having no central vacuole and no or only a few starch grains. Evidently, some essential changes necessary for the embryogenic response can be induced by glutamine starvation only in pollen grains at a specific stage.

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Marigold (Tagetes patula L.) hairy roots induced by infection with Agrobacterium rhizogenes produced α-terthienyl when grown in darkness, and an n-hexane extract of the roots showed nematocidal activity. Depending on the hairy root line used, the level of α-terthienyl varied from 15 to 1268 μg per g dry weight, a level that corresponded to 0.15 to 12.7-fold that in intact roots. Analysis by HPLC indicated that the nematocidal activity was due predominantly to α-terthienyl. However, it is suggested that nematocidal compounds other than α-terthienyl are present in hairy roots cultured in the dark for long periods or in the light.

We examined the effect of ectopic expression of WUS on the morphology of tobacco seedlings and the segments in vitro. WUS was amplified from Arabidopsis cDNA and introduced into the tobacco genome under the transcriptional control of the beta-estradiol-inducible expression system. When 1-week-old transgenic seedlings were cultured in the presence of beta-estradiol, only the root tip region developed bulbous tissues followed by shoot formation and plant regeneration, suggesting its applicability for improving the strategy of micropropagation in recalcitrant species. Evident abnormality was not observed in the cotyledons, hypocotyl nor root except for the tip. However, ectopic WUS seemed to be functional in those parts through the observation of gene expression and the behavior of cultured segments. Small root segments with a root tip treated with beta-estradiol also showed bulbing but no shoots unless exogenous cytokinin was supplied. These findings suggest the existence of unknown factors regulating ectopic WUS function in the seedling.