RESUMEN

Bacillus cereus AR156 is a plant growth-promoting rhizobacterium that induces resistance against a broad spectrum of pathogens including Pseudomonas syringae pv. tomato DC3000. This study analyzed AR156-induced systemic resistance (ISR) to DC3000 in Arabidopsis ecotype Col-0 plants. Compared with mock-treated plants, AR156-treated ones showed an increase in biomass and reductions in disease severity and pathogen density in the leaves. The defense-related genes PR1, PR2, PR5, and PDF1.2 were concurrently expressed in the leaves of AR156-treated plants, suggesting simultaneous activation of the salicylic acid (SA)- and the jasmonic acid (JA)- and ethylene (ET)-dependent signaling pathways by AR156. The above gene expression was faster and stronger in plants treated with AR156 and inoculated with DC3000 than that in plants only inoculated with DC3000. Moreover, the cellular defense responses hydrogen peroxide accumulation and callose deposition were induced upon challenge inoculation in the leaves of Col-0 plants primed by AR156. Also, pretreatment with AR156 led to a higher level of induced protection against DC3000 in Col-0 than that in the transgenic NahG, the mutant jar1 or etr1, but the protection was absent in the mutant npr1. Therefore, AR156 triggers ISR in Arabidopsis by simultaneously activating the SA- and JA/ET-signaling pathways in an NPR1-dependent manner that leads to an additive effect on the level of induced protection.

Asunto(s)

Arabidopsis/fisiología , Bacillus cereus/metabolismo , Enfermedades de las Plantas/microbiología , Reguladores del Crecimiento de las Plantas/metabolismo , Inmunidad de la Planta/fisiología , Arabidopsis/genética , Arabidopsis/inmunología , Arabidopsis/microbiología , Bacillus cereus/crecimiento & desarrollo , Ciclopentanos/metabolismo , Etilenos/metabolismo , Regulación de la Expresión Génica de las Plantas/inmunología , Genes de Plantas/genética , Glucanos/metabolismo , Peróxido de Hidrógeno/metabolismo , Oxilipinas/metabolismo , Enfermedades de las Plantas/genética , Enfermedades de las Plantas/inmunología , Reguladores del Crecimiento de las Plantas/genética , Pseudomonas syringae/patogenicidad , Ácido Salicílico/metabolismo , Transducción de Señal/fisiología

RESUMEN

AIM:To investigate the effect of Boschniakia rossica (BR) extract on expression of GST-P, p53 and p21(ras) proteins in early stage of chemical hepatocarcinogenesis in rats and its anti-inflammatory activities.METHODS:The expression of tumor marker-placental form glutathione S-transferase (GST-P), p53 and p21(ras) proteins were investigated by immunohisto-chemical techniques and ABC method. Anti-inflammatory activities of BR were studied by xylene and croton oil-induced mouse ear edema, carrageenin, histamine and hot scald-induced rat pow edema, adjuvant-induced rat arthritis and cotton pellet induced mouse granuloma formation methods.RESULTS:The 500mg/kg of BR-H2O extract frac-tionated from BR-Methanol extract had inhibitory effect on the formation of DEN-induced GST-P-positive foci in rat liver (GST-P staining was 78% positive in DEN+AAF group vs 20% positive in DEN+AAF+BR group, P<0.05) and the expression of mutant p53 and p21(ras) protein was lower than that of hepatic preneoplastic lesions (33% and 22% positive respectively in DEN+AAF group vs negative in DEN+AAF+BR group). Both CH(2)Cl(2) and H(2)O extracts from BR had anti-inflamatory effect in xylene and crotonoil induced mouse ear edema (inhibitory rates were 26%-29% and 35%-59%, respectively). BR H(2)O extract exhibited inhibitory effect in carrageenin, histamine and hot scald-induced hind paw edema and adjuvant-induced arthritis in rats and cotton pellet-induced granuloma formation in mice.CONCLUSION:BR extract exhibited inhibitory effect on formation of preneoplastic hepatic foci in early stage of rat chemical hepato-carcinogenesis.Both CH(2)Cl(2) and H(2)O extracts from BR exerted anti-inflammatory effect in rats and mice.

RESUMEN

The mono-component ribozyme RZ1, RZ3 and RZ4 were ligated in different orders into two tri-component ribozymes RZ134 and RZ413.Both tri-component ribozymes could cleave individual specific substrate sequences from different regions of the tobacco mosaic virus (TMV) RNA. The cleavage efficiency and specificity of each unit-ribozymes in the tri-component ribozymes to its substrate was similar to its mono-ribozyme counterpart. When the three substrates were mixed and used as substrates for the tri-component ribozymes, only the activity of the unit-ribozymes RZ4 was clearly observed, the activities of the other two unit-ribozymes were greatly reduced. The reduction was mainly due to the fact that the two substrates BT2(+) and BT2(-) for RZ1 and RZ3 were complementary in sequence to each other and therefore formed duplex in the target region, thus must have strongly prevented the two ribozymes from forming the correct structures required for cleavage activity. In addition to its activity on the substrate BT2(+), the ribozyme RZ1 was found unexpectedly to be able to cleave BT4(-) specifically into various unique products.

RESUMEN

Two defective mutants of the tobacco mosaic virus (TMV), TMVRP and TMVCP were constructed and assembled in vitro. In TMVRP, the 3'-end and part of the TMV coat protein (CP) gene was deleted; in TMRCP, most of the replicase genes were deleted. These mutant particles were separately or complementally inoculated into the tobacco protoplasts by electroporation. The synthesis of TMV coat protein was deteted by immuno dot-blot technique at 2 h after inoculation only in those complementally infected protoplasts. In addition, using the RT/PCR technique, the minus-strand viral RNA of the TMV 3'-end including CP gene was also only detected in those protoplasts which were complementally infected with both of the mutant particles. The synthesis of the minus-strand RNA started to be detectable at 1h after inoculation and it was confirmed by Southern blot analysis.