In vitro propagation of bulblets and LC-MS/MS analysis of isosteroidal alkaloids in tissue culture derived materials of Chinese medicinal herb Fritillaria cirrhosa D. Don.

BACKGROUND: Fritillaria cirrhosa, an important Chinese medicinal herb, is a Class-III protected and highly exploited species by pharmaceutical industry. Dwindling wild populations of species are unable to meet market demand. Therefore, this study was carried out to develop an in vitro propagation method for bulblet production. Also, the study aimed to carry out LC-MS/MS analysis of tissue culture-derived bulblets and callus for the presence of isosteroidal alkaloids (peimissine, verticine, and verticinone), and compare its quantities with commercially available crude drug samples. RESULTS: In vitro seed germination (91%) of F. cirrhosa was achieved on Murashige and Skoog's basal medium (MSBM) supplemented with 6-benzylaminopurine (1 mg L-1) and α-naphthalene-acetic-acid (0.4 mg L-1). On transfer of germinated seeds from Petri-dishes to glass bottles containing hormone-free MSBM, 37.5% of seedlings developed bulblets after 3 months of incubation. Regeneration and multiplication of bulblets were achieved by culture of transverse sections of bulblets on 1/2 X MSBM. By repeated subcultures at an interval of 2 months, 3072 bulblets weighing 1270 g could be produced at the end of 5th subculture. LC-MS/MS analysis showed a significant presence of peimissine in in vitro bulblets while callus incubated in the dark showed presence of peimissine and verticine. CONCLUSION: The study reports an efficient in vitro propagation method of bulblets production of F. cirrhosa and presence of some isosteroidal alkaloids in tissue culture-derived bulblets and callus. The study could be of immense help in production of F. cirrhosa bulblets and callus under laboratory conditions round the year. Also, these results can be used further to investigate production of isosteroidal alkaloids in bioreactors at commercial scale using liquid and cell suspension cultures. Thus, we not only can reduce our dependence on collections from natural habitats, but also can help in in situ conservation of this important species.

Production of soft rot resistant calla lily by expressing a ferredoxin-like protein gene (pflp) in transgenic plants.

An efficient protocol for the Agrobacterium tumefaciens-mediated transformation of calla lily (Zantedeschia elliottiana (W. Wats.) Engl. cultivar 'Florex Gold') is described. Shoot basal discs were co-cultivated with A. tumefaciens C58C1 carrying a plasmid containing neomycin phosphotransferase (nptII) and plant ferredoxin-like protein (pflp) genes. After Agrobacterium co-cultivation, the shoot basal discs were exposed to 100 mg l(-1) kanamycin for selection. Twenty-eight out of 260 discs (10.8%) were found to have survived and produced shoot clusters. Twenty-six of these were confirmed to contain the pflp transgene by PCR, ending up in 10% transformation efficiency. The disease resistance investigation revealed that 18 transgenic plants exhibited resistance to soft rot disease caused by Erwinia carotovora subsp. carotovora. The presence of pflp gene was demonstrated by PCR, and its accumulation and activity was confirmed by Western blot and disease resistance assay. This was the first report to show the successful transformation and resistance to a bacterial pathogen in Zantedeschia. The protocol is useful for the quality improvement of calla lily through genetic transformation.

Disease resistance to bacterial pathogens affected by the amount of ferredoxin-I protein in plants.

SUMMARY Ferredoxin-I (Fd-I) is a fundamental protein that is involved in several metabolic pathways. The amount of Fd-I found in plants is generally regulated by environmental stress, including biotic and abiotic events. In this study, the correlation between quantity of Fd-I and plant disease resistance was investigated. Fd-I levels were increased by inoculation with Pseudomonas syringae pv. syringae but were reduced by Erwinia carotovora ssp. carotovora. Transgenic tobacco over-expressing Fd-I with the sense sweet pepper Fd-I gene (pflp) was resistant to E. carotovora ssp. carotovora and the saprophytic bacterium P. fluorescens. By contrast, transgenic tobacco with reduced total Fd-I and the antisense pflp gene was susceptible to E. carotovora ssp. carotovora and P. fluorescens. Both of these transgenic tobaccos were resistant to P. syringae pv. syringae. By contrast, the mutated E. carotovora ssp. carotovora, with a defective harpin protein, was able to invade the sense-pflp transgenic tobacco as well as the non-transgenic tobacco. An in vitro kinase assay revealed that harpin could activate unidentified kinases to phosphorylate PFLP. These results demonstrate that Fd-I plays an important role in the disease defence mechanism.

Expression of the hypersensitive response-assisting protein in Arabidopsis results in harpin-dependent hypersensitive cell death in response to Erwinia carotovora.

Active defense mechanisms of plants against pathogens often include a rapid plant cell death known as the hypersensitive cell death (HCD). Hypersensitive response-assisting protein (HRAP) isolated from sweet pepper intensifies the harpin(Pss)-mediated HCD. Here we demonstrate that constitutive expression of the hrap gene in Arabidopsis results in an enhanced disease resistance towards soft rot pathogen, E. carotovora subsp. carotovora. This resistance was due to the induction of HCD since different HCD markers viz. Athsr3, Athsr4, ion leakage, H(2)O(2) and protein kinase were induced. One of the elicitor harpin proteins, HrpN, from Erwinia carotovora subsp. carotovora was able to induce a stronger HCD in hrap-Arabidopsis than non-transgenic controls. To elucidate the role of HrpN, we used E. carotovora subsp. carotovora defective in HrpN production. The hrpN(-) mutant did not induce disease resistance or HCD markers in hrap-Arabidopsis. These results imply that the disease resistance of hrap-Arabidopsis against a virulent pathogen is harpin dependent.