Plant growth promoting rhizobacteria (PGPR) are known to confer disease resistance to plants. Bacillus sp. JS demonstrated antifungal activities against five fungal pathogens in in vitro assays. To verify whether the volatiles of Bacillus sp. JS confer disease resistance, tobacco leaves pre-treated with the volatiles were damaged by the fungal pathogen, Rhizoctonia solani and oomycete Phytophthora nicotianae. Pre-treated tobacco leaves had smaller lesion than the control plant leaves. In pathogenesis-related (PR) gene expression analysis, volatiles of Bacillus sp. JS caused the up-regulation of PR-2 encoding β-1,3-glucanase and acidic PR-3 encoding chitinase. Expression of acidic PR-4 encoding chitinase and acidic PR-9 encoding peroxidase increased gradually after exposure of the volatiles to Bacillus sp. JS. Basic PR-14 encoding lipid transfer protein was also increased. However, PR-1 genes, as markers of salicylic acid (SA) induced resistance, were not expressed. These results suggested that the volatiles of Bacillus sp. JS confer disease resistance against fungal and oomycete pathogens through PR genes expression.

We tested the possibility of plantlet formation via somatic embryogenesis with leaf segments and mature zygotic embryos from a rare and endangered tree species, Oplopanax elatus. To induce calli, explants were cultured under darkness in a solid MS medium containing 3% sucrose, lg L 1 glutamine, and 0.3% gelrite. Treatment supplements included 2,4-D alone or in combination with thidiazuron. Generally, callus induction and growth were good from leaf explants, whereas embryogenic calli could be induced only from zygotic embryos. These embryogenic calli were white or pale yellow and very friable. ABA and activated charcoal appeared to be important factors when inducing somatic embryos, with optimum levels being 0.1 mg L 1 and 0.02%, respectively. Many somatic embryos showed abnormalities during their development on the germination medium, but 35% could be converted if placed on a medium containing gibberellic acid (GA3). The germinating embryos sometimes formed secondary embryos at the lower portion of the hypocotyls. Normal or converted plantlets were acclimatized in an artificial soil mixture; their survival was about 60% after two months. This culturing system provides a feasible approach for regenerating plants, via somatic embryogenesis, from mature zygotic embryos.

No abstract

No abstract

A somatic embryogenesis and plant regeneration study was conducted with a rare and endangered species, Acanthopanax seoulenses, and various factors affecting somatic embryo induction were evaluated. The frequency of embryogenic callus induction was slightly better on wounded seeds compared with non-wounded ones. The optimum medium to induce somatic embryos (SEs) from embryogenic cells was MS medium supplemented with 3% sucrose and 0.1À0.2 mg/l abscisic acid (ABA), or MS medium with 3% sucrose and 0.1 mg/l ABAþ0.02% activated charcoal. Gibberellic acid resulted in a positive effect on SE germination, but there were no differences in the range of 0.1 to 1.0 mg/l. SE germination and plant conversion rate were different in the two gelling agents: agar-gelled medium was slightly better than gelite-gelled medium, and the highest plant conversion, 78AE18.2%, was achieved in agar-gelled medium. Regenerated plantlets were successfully acclimatized in artificial soil mixture, and more than 98% of the plants survived in vermiculite or an equal volume mixture of vermiculite and peat moss. Results suggest that the rare and endangered species is able to propagate effectively via the somatic embryogenesis system.