Geosmin-producing Species of Coelosphaerium (Synechococcales, Cyanobacteria) in Lake Shinji, Japan.

In Lake Shinji, Japan, periodic outbreaks of musty odour have occurred since mid-May 2007. Although the substance responsible for the odour was identified as geosmin, the odour-producing organism was unknown. We cultivated an axenic unialgal strain and determined that a species of Coelosphaerium (Synechococcales) was responsible for the production of geosmin in Lake Shinji. Our analysis was conducted using gas chromatography/mass spectrometry to determine the odorous compound. To determine the algae species, it was observed by optical microscopy to describe its morphological characteristics and the polymerase chain reaction was used to characterise the nucleotide sequence of the 16S rRNA gene and the 16S-23S rRNA internal transcribed spacer region. In addition, we explored the relationship between the number of cells of the Coelosphaerium sp. and the concentration of geosmin. In conclusion, geosmin, the cause of the musty odour in Lake Shinji in autumn 2009, was produced by Coelosphaerium sp., and to our knowledge, this is the first report of a geosmin-producing species in the family Coelosphaeriaceae.

Cryopreservation of immature seeds of Bletilla striata by vitrification.

An efficient protocol was established for the cryopreservation of immature seeds of a terrestrial orchid, Bletilla striata. Immature seeds collected 2-4 months after pollination (MAP) were treated using three different cryogenic procedures: (1) direct plunging into liquid nitrogen, (2) vitrification, and (3) vitrification with preculture. When immature seeds collected 3 MAP and 4 MAP were precultured for 3 days on New Dogashima medium supplemented with 0.3 M sucrose and cryopreserved by vitrification, the survival rate after preservation, as assessed by staining with 2,3,5-triphenyltetrazolium chloride, was 92% and 81%, respectively. Immature seeds thus treated showed no decrease in germination rate relative to untreated immature seeds, and they developed into normal plantlets in vitro.

Effect of sugar type on the efficiency of plant regeneration from protoplasts isolated from shoot tip-derived meristematic nodular cell clumps of Lilium x formolongi hort.

Suspension cultures composed of meristematic nodular cell clumps of Lilium x formolongi hort were established from shoot tips placed on MS medium supplemented with 1 mg/l picloram and 30 g/l sucrose, glucose, fructose or sorbitol. Protoplasts isolated from these cultures were embedded in 1 g/l gellan gumsolidified 1/2MS medium with 1 mg/l picloram and the different kinds of sugars at 0.5 M, and cultured at 25 °C in the dark. The highest plating efficiency (13.7%) was obtained when the protoplasts were isolated from the cell clumps which had been subcultured in MS medium containing glucose and were likewise cultured in MS medium supplemented with 0.5 M glucose. Plants were regenerated from the protoplast-derived calli on 1/2MS medium containing 2.5-10 g/l sucrose or 5-10 g/l glucose. These results suggest that the kinds of sugar and concentration are important parameters affecting protoplast isolation, proliferation and plant regeneration in L. x formolomgi hort.