The use of phosphinothricin resistance as selectable marker for genetic transformation of grapevine

A transformation procedure with the bar gene as a selectable marker was established via Agrobacterium-mediated transformation using strain LBA4404 harbouring the vector pPZP200-bar-gus-intron. Recreation of embryogenic cells from transformation stress in PPT free medium for four weeks improved viability and number of GUS expressing cells. Concentration of 2.5 mg·l-1 PPT yielded highest selection efficiency. Transgenicity of the regenerated grapevine plants was confirmed by histochemical GUS assay and bar specific PCR and RT/PCR. With the described procedure, 20 % of regenerated embryos could be converted into transgenic grapevines.

Preservation of endangered Tunisian grapevine cultivars using embryogenic cultures

The preservation of embryogenic lines derived from several endangered local grapevine cultivars was studied. Embryogenic calluses were obtained from immature anthers of eight cultivars, sampled on both fruity-cuttings and field grown vines. Anthers at the 'separated flower' stage, derived from fruity-cuttings, resulted in an increased induction of somatic embryogenesis, compared to those derived from the The preservation of embryogenic lines derived from several endangered local grapevine cultivars was studied. Embryogenic calluses were obtained from immature anthers of eight cultivars, sampled on both fruity-cuttings and field grown vines. Anthers at the 'separated flower' stage, derived from fruity-cuttings, resulted in an increased induction of somatic embryogenesis, compared to those derived from the 15.6% and 34.8% in 'Kahli Kerkennah' and 'Muscat Raf-raf' cultivars, respectively. Although, morphological diversifications of pro-embryogenic calluses (several necrosis and spontaneous maturation) were observed on the induction mediumafter 5 subcultures. The reduction of 2,4-D and TDZ levels to 4.52 \u3bcM and 2.89 \u3bcM respectively, induced granular and yellowish embryogenic material. Thus, Ch\ue9e and Pool (1987) (CP) enriched with 4.52 \u3bcM of 2,4-D and 2.89 \u3bcM of TDZ revealed to be the most appropriate for long-term maintenance. In fact, all the cultivars presented high and regular embryo maturation rates after 12, 24, 36 and 48 months of cultivation on this medium, under light conditions. After 4 years, they still exhibit high germination and regeneration abilities. Germination of somatic embryos was achieved on Murashige and Skoog (1962) basal-medium, with rates ranging from 69% to 96%. Only 5% of somatic embryos were concerned by morphological variations. The regenerated plantlets presented a normal phenotype under controlled greenhouse conditions, compared to mother plants

Preservation of endangered Tunisian grapevine cultivars using embryogenic cultures

The preservation of embryogenic lines derived from several endangered local grapevine cultivars was studied. Embryogenic calluses were obtained from immature anthers of eight cultivars, sampled on both fruity-cuttings and field grown vines. Anthers at the 'separated flower' stage, derived from fruity-cuttings, resulted in an increased induction of somatic embryogenesis, compared to those derived from the The preservation of embryogenic lines derived from several endangered local grapevine cultivars was studied. Embryogenic calluses were obtained from immature anthers of eight cultivars, sampled on both fruity-cuttings and field grown vines. Anthers at the 'separated flower' stage, derived from fruity-cuttings, resulted in an increased induction of somatic embryogenesis, compared to those derived from the 15.6% and 34.8% in 'Kahli Kerkennah' and 'Muscat Raf-raf' cultivars, respectively. Although, morphological diversifications of pro-embryogenic calluses (several necrosis and spontaneous maturation) were observed on the induction mediumafter 5 subcultures. The reduction of 2,4-D and TDZ levels to 4.52 μM and 2.89 μM respectively, induced granular and yellowish embryogenic material. Thus, Chée and Pool (1987) (CP) enriched with 4.52 μM of 2,4-D and 2.89 μM of TDZ revealed to be the most appropriate for long-term maintenance. In fact, all the cultivars presented high and regular embryo maturation rates after 12, 24, 36 and 48 months of cultivation on this medium, under light conditions. After 4 years, they still exhibit high germination and regeneration abilities. Germination of somatic embryos was achieved on Murashige and Skoog (1962) basal-medium, with rates ranging from 69% to 96%. Only 5% of somatic embryos were concerned by morphological variations. The regenerated plantlets presented a normal phenotype under controlled greenhouse conditions, compared to mother plants

High efficiency and informativeness of a set of SNP molecular markers in Tunisian local grapevines discrimination

The sequencing of 3.726 kb of grape DNA genome among 44 local Tunisian grapevine accessions has allowed the detection of 73 SNPs which gave an average of one SNP every 51 bp. Based on this set of SNP molecular markers, the analyzed samples exhibited important levels of genetic polymorphism which confirms previous reports and highlights the utility of Tunisian grapevine germplasm as a reservoir of genetic polymorphism which can be exploited for breeding and conservation programs of the species. Moreover, these results showed the efficiency of SNP molecular marker in genetic structure analysis. Thus, our results suggest two probable origins for Tunisian cultivars which confirm previous molecular studies and historical data. The set of 73 SNPs allowed the unambiguous discrimination of all the studied accessions. Our analysis showed that a set of 27 SNPs were able to identify all the analyzed cultivars. On the other hand, a set of 22 SNPs is shown sufficient to discriminate all the wild accessions. Those two SNP sets could be taken into consideration in further studies concerning cultivars identification and wild accessions discrimination of the species Vitis vinifera L

Field-induced spin cycloidal modulation to antiferromagnetic transition and possible flexomagnetic effect in BiFeO3 nanoparticles

Beyond its various properties, the model multiferroic BiFeO3 (BFO) displays a rich magnetic structure illustrated in the bulk by its long period (∼62 nm) spin cycloidal modulation. Here, BFO nanoparticles are produced by a facile hydrothermal method and show average size of 8 nm and a narrow size distribution, as determined using x-ray diffraction analysis and transmission electron microscopy images. Mössbauer spectrometry (MS) unambiguously reveals that a cycloidal modulation does still exists with particles about 5 times smaller than the bulk cycloid. Combining macroscopic magnetic measurements and in situ Mössbauer spectrometry, we demonstrate that a critical magnetic field of ∼0.2 T destabilizes the cycloidal modulation to lead to a homogenous antiferromagnetic state, as the result of magnetic anisotropy due to magnetoelastic and surface-confinement effects. More interestingly, further increasing of the external magnetic field up to 8 T does not change the average magnetic hyperfine field and results into multiple Mössbauer sextets we propose to explain by a flexomagnetic effect i.e. magnetic anisotropies resulting from strain gradients due to a continuous variation of the coupling between magnetization and the structural distortion from the surface to the particle core

Development of an SSR-based identification key for Tunisian local almonds

19 Pags., 4 Figs., 2 Tabls.Ten simple sequence repeat (SSR) loci were used to study polymorphism in 54 almond genotypes. All genotypes used in this study originated from almond-growing areas in Tunisia with different climatic conditions ranging from the sub-humid to the arid and are preserved in the national collection at Sidi Bouzid. Using ten SSR, 130 alleles and 250 genotypes were revealed. In order to develop an identification key for each accession, the data were analysed separately for each microsatellite marker. The most polymorphic microsatellite (CPDCT042) was used as a first marker. Two microsatellite loci (CPDCT042 and CPDCT025) were sufficient to discriminate among all accessions studied. Neighbour-joining clustering and principal coordinate analysis were performed to arrange the genotypes according to their genetic relationships and origin. The results are discussed in the context of almond collection management, conformity checks, identification of homonyms, and screening of the local almond germplasm. Furthermore, this microsatellite-based key is a first step toward a marker-assisted identification almond database.Financial support was provided in part by the Tunisian Ministry of Higher Education, Scientific Research and Technology, the Spanish Ministry of Science and Innovation (AGL2008-00283/AGR co-financed by FEDER), the Aragon Government (Group A44), and the Agencia Española de Cooperación Internacional (A/5339/06 and A/8334/07).Peer reviewe