Antifungal Activity of Volatile Components Extracted from Leaves, Stems and Flowers of Four Plants Growing in Tunisia

Volatile components extracted from the leaves, stems and flowers of Lantana camara, Malvaviscus arboreus, Hibiscus rosa-sinensis cv. red flowers and white flowers were tested against the fungi Alternaria solani, Botrytis cinerea, Fusarium solani f. sp. cucurbitae, F. oxysporum f. sp. niveum, Pythium ultimum, Rhizoctonia solani and Verticillium dahliae. The strongest inhibitory effect of the extracts was found with volatile components extracted from the stems and the flowers. Complete inhibition was achieved against V. dahliae. The weakest effect was against P. ultimum. Volatile components extracted from the leaves were not effective

Resistencia aumentada a Rhizoctonia solani por la expresión combinada de quitinasa y proteínas inactivantes de los ribosomas en patatas transgénicas

Potato (Solanum tuberosum L.) is susceptible to many fungal pathogens including Rhizoctonia solani. In the present study, the potato cultivar Desirée was transformed via Agrobacterium tumefaciens strain GV3101 containing the binary plasmid pGJ132 harboring both the chitinase (chiA) and rip30 genes. The potato leaf disc was used as an explant for transformation. PCR, Southern blot and Western blot were used for characterization of the transgenic plants. In this study it was shown that not all the plants developed in selective medium were positive for the corresponding gene using the PCR technique. Southern blot analysis confirmed that transgenic plants integrated 2-3 copies of chiA and rip30 genes respectively into their genome. The expression of the CHIA and RIP30 proteins was confirmed in the leaf extracts of the transgenic clones by Western blot analysis. Transgenic potato plants expressing rip30 and chiA genes showed enhanced resistance to R. solani in a greenhouse assay.La patata (Solanum tuberosum L.) es susceptible a muchos hongos fitopatógenos, incluyendo Rhizoctonia solani. En el presente estudio, se transformó el cultivar de patata ‘Desirée’ mediante Agrobacterium tumefaciens, cepa GV3101, que contiene el plásmido binario pGJ132 que alberga los genes quitinasa (chiA) y rip30. Se utilizaron discos de hojas como explante para la transformación de plantas. Se utilizaron las técnicas de PCR, Southern y Western blot para la caracterización de las plantas transgénicas. En este estudio se demostró, mediante PCR, que no todas las plantas que se desarrollaron en medio selectivo fueron positivas para el gen correspondiente. El análisis de Southern blot confirmó que las plantas transgénicas integraron en su genoma 2-3 copias de los genes chiA y rip30. Se llevó a cabo un ensayo de invernadero para evaluar la resistencia a R. solani de los clones transgénicos que expresan los transgenes. Las plantas transgénicas que expresan los genes rip30 y chiA mostraron una resistencia completa a R. solani

Ribosome Inactivating Protein of barley enhanced resistance to Rhizoctonia solani in transgenic potato cultivar 'Desirée' in greenhouse conditions

In the present study, the potato cultivar 'Desirée' was transformed via Agrobacterium tumefaciens strain LBA4404 containing the plasmid pBIN19 which harbors the Ribosome Inactivating Protein (rip30). The potato leaf discs were used as an explant for transformation. The in vitro regeneration parameters (percentage of callus regenerated, number of shoots per callus, percentage of regenerated roots and percentage of the transgenic plants) were evaluated. The PCR technique was used for identification of transformed plants. Southern and Western blot analyses were applied for molecular characterization of the transgenic clones. A greenhouse assay was carried out to evaluate the resistance to Rhizoctonia solani pathogen of transgenic clones expressing the rip30 gene. The results revealed that not all the plants developed in selective medium were positive for the corresponding gene using the PCR technique. Southern blot analysis demonstrated that the tested transgenic plants integrated three copies of rip30 gene into their genome. The expression of the RIP30 protein was confirmed in the leaf extracts of the transgenic clones by Western blot analysis. Resistance evaluation of the transgenic plants in greenhouse conditions showed that disease incidence and severity were reduced for R. solani

Variability of chemical composition and biological activities of Allium triquetrum L. essential oils

The present work describes the chemical composition and evaluates the antimicrobial properties of the essential oils from the Tunisian Allium triquetrum L. It is particularly interesting study because there are no reports on of this species in any sector and with specific chemical composition. The chemical composition of four essential oil samples (flowers, stems, leaves and bulbs) of A. triquetrum, obtained separately by hydrodistillation were analyzed by combination of GC-FID and GCMS. Altogether, 45 compounds were identified representing 90.5-95.3% of the total oil content. The chemical composition of bulbs oil was characterized by a high proportion of sulfurous compounds (81.9%) among which dipropyl trisulfide (11.7%) and di-2-propenyl trisulfide (10.0%) were the predominant compounds. The oxygenated sesquiterpenes represent the major fraction (79.2%) in stem oil giving T-cadinol (26.8%), α-eudesmol (11.4%) and β-eudesmol (16.8%) as the main components; they were present also in leaf oil. We also noted the presence of some alkane compounds such n-nonadecane (13.3%) in flower oil. Some compounds identified in this plant have not been reported about other species of Allium such elemol, β-copaen-4-α-ol, globulol, viridiflorol, guaiol, eremoligenol, α-eudesmol, β-eudesmol and pimaradiene. Furthermore, the isolated oils were evaluated for antibacterial and antifungal activities. All the oils exhibited significant in vitro antibacterial activity, especially against Enterococcus faecalis and Staphylococcus aureus. The oil obtained from the stem, leaf and bulbs exhibited an interesting antibacterial activity, with a Minimum Inhibitory Concentration (MIC) of 31.25µg/mL against S. aureus. It was found also that stem and bulbs oil showed the highest growth inhibition of almost fungi especially against Fusarium solani (75.33and 71.33%, resp.) even greater than the positive control: benomyl (69.33%). The results indicate that the essential oil of A. triquetrum contains chemical compounds with good potential for application in natural health products and in the protection of agriculture products