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The extension of Jatropha curcas L. cultivation as a biofuel feedstock species requires the distribution of a very large number of plants to the producers in a very short period of time. These plants have to be able to give a high oil yield and be morphologically and phenotypically homogeneous to facilitate cultural operations. If high oil content can be obtained by varietal selection, the achievement of homogeneous material passes by the in vitro propagation. Various methods of mass production of plant material by axenic culture have been published. This study reviews the protocols published for in vitro propagation of J. curcas and discusses their applicability to an industrial scale. [PUBLICATION ABSTRACT]

A total of 669 individual cow milk samples originating from asymptomatic cows from 16 dairy farms were examined for the presence of microorganisms with the potential to cause mastitis. Coagulase-negative staphylococci clearly predominated (53.5% positive samples) followed by streptococci and enterococci (both occurring in 16.1% samples). Among streptococci, so-called mastitis streptococci (S. uberis, S. dysgalactiae and S. agalactiae) prevailed (11.7% positive samples). Enterobacteriaceae were found in 10.0% samples, most of which (6.6% samples) were positive for Escherichia coli. Yeasts (mainly Candida spp.) were found in 8.2% samples. One of the major mastitis pathogens, Staphylococcus aureus subsp. aureus, was isolated from 9.0% of samples. S. aureus isolates were further characterised in terms of their capability to form biofilm, antimicrobial susceptibility and clonality (PFGE). All S. aureus isolates were capable of biofilm formation and were generally susceptible to the majority of tested antibiotics. The exception was ampicillin, resistance to which was observed in 27.7% isolates. Therefore, the relatively frequent occurrence of S. aureus could be attributed to persistent intramammary infections due to biofilm formation rather than low efficacy of particular antibiotics. PFGE analysis revealed clonal spread of certain S. aureus isolates within and between farms indicating that certain lineages of S. aureus mastitis strains are particularly successful.

The substrates used for ex vitro acclimatization may affect the performance of the plants by means of physical, chemical, and biological characteristics. The objective of this study was to evaluate the effects of eight substrates on the acclimatization of micropropagated anthurium plantlets. The experiment was carried out in the greenhouse of the Department of horticulture, Federal University-Ceara State (UFC), in Fortaleza. Plantlets obtained by tissue culture, with approximately 3.8 cm of height, were transplanted to plastic trays composed of 54 cells (80 cm3cell-1) and irrigated with nutritive solution CE (1.0 dS.m-1) alternated with water. Ninety days upon transplant, plant height, fresh weight of the shoots and roots, dry weight of shoots and roots, and leaf number were evaluated. The experimental design was a completely randomized system, with eight treatments (coir dust, coir dust plus carnauba straw, coir dust plus carbonated rice straw, humus, carnauba straw, vermiculite, commercial 1, and commercial 2) and 24 replications. Anthurium plantlets grown in dried coir dust substrate showed the best development and growth, suggesting that the physical-chemical characteristics (CTC, pH, EC, porosity, water retention, and aeration) presented by this substrate are the most adequate to the acclimatization of anthurium plantlets. Plantlets acclimatized in the vermiculite substrate also presented satisfactory development.

Five retrotransposon families of rice (Tos1-Tos5) have been reported previously. Here we report 15 new retrotransposon families of rice (Tos6-Tos20). In contrast to yeast and Drosophila retrotransposons, all of the rice retrotransposons examined appear inactive (or almost inactive) under normal growth conditions. Three of the rice retrotransposons (Tos10, Tos17, and Tos19) are activated under tissue culture conditions. The most active one, Tos17, was studied in detail. The copy number of Tos17 increased with prolonged culture period. In all of the plants regenerated from tissue cultures, including transgenic plants, 5 to 30 transposed Tos17 copies were detected. The transcript of Tos17 was only detected under tissue culture conditions, indicating that the transposition of Tos17 is mainly regulated at the transcriptional level. To examine the target-site specificity of Tos17 transposition, sequences flanking transposed Tos17 copies were analyzed. At least four out of eight target sites examined are coding regions. Other target sites may also be in genes because two out of four were transcribed. The regenerated plants with Tos17-insertions in the phytochrome A gene and the S-receptor kinase-related gene were identified. These results indicate that activation of Tos17 is an important cause of tissue culture-induced mutations. Tissue culture-induced activation of Tos17 may be a useful tool for insertional mutagenesis and functional analysis of genes.

As an important antioxidant for plants and humans, L-ascorbic acid (AsA) can scavenge reactive oxygen species and can be regenerated from its oxidized form in a reaction catalyzed by dehydroascorbate reductase (DHAR). To analyse the effect of overexpressing DHAR on tomato, an expression vector containing potato cytosolic DHAR (DHAR1) or chloroplastic DHAR (DHAR2) cDNA driven by a cauliflower mosaic virus 35S promoter was transferred into tomato plants. Compared with the wild type (WT), DHAR1 overexpression increased DHAR activity and AsA content in both leaves and fruits, while DHAR2 overexpression increased DHAR activity and AsA content mainly in leaves. DHAR1 and DHAR2 overexpression increased the chlorophyll content and photosynthetic rate of transgenic lines, but had no effect on plant height and stem diameter. Furthermore, the germination rate, plant fresh weight, seedling length and chlorophyll content of transgenic DHAR1 and DHAR2 plants under salt stress were higher than those of WT plants. In addition, the transgenic plants also exhibited considerable tolerance to oxidative damage induced by methyl viologen (MV). Taken together, these results indicated that overexpressing potato DHAR1 and DHAR2 enhanced the level of AsA in tomato and, consequently, increased the tolerance of tomato to salt and MV stress.

El rescate de híbridos de cruces intergenéricos entre la lechosa (Carica papaya L.) y otras especies de vasconcelleas (antes conocidas como caricas) posibilita la transferencia de genes desde las especies silvestres hacia la cultivada. El objetivo del presente trabajo fue la obtención y evaluación de plantas híbridas mediante el rescate y regeneración de embriones u óvulos después del cruce entre C. papaya y Vasconcellea cauliflora. Se obtuvo un porcentaje de fructificación entre 0 y 76% de acuerdo al tipo de lechosa usada en el cruce. En los frutos, las semillas fueron vanas, inmaduras o contenían embriones cigóticos. En la mayoría de ellas ocurrió la poliembrionía cigótica in vivo, aún cuando también se produjeron híbridos individuales. Se logró el desarrollo, germinación y multiplicación de embriones híbridos, y la regeneración de plantas in vitro. Las plantas sembradas en campo produjeron flores andróicas y andromonóicas.

TDZ (N-phenyl-N′-1,2,3-thidiazol-5-ylurea) is a substituted phenylurea compound which was developed for mechanized harvesting of cotton bolls and has now emerged as a highly efficacious bioregulant of morphogenesis in the tissue culture of many plant species. Application of TDZ induces a diverse array of cultural responses ranging from induction of callus to formation of somatic embryos. TDZ exhibits the unique property of mimicking both auxin and cytokinin effects on growth and differentiation of cultured explants, although structurally it is different from either auxins or purine-based cytokinins. A number of physiological and biochemical events in cells are likely to be influenced by TDZ, but these may or may not be directly related to the induction of morphogenic responses, and hence, the mode of action of TDZ is unknown. However, the recent approaches applied to study the morphogenic events initiated by TDZ are clearly beginning to reveal the details of a variety of underlying mechanisms. Various reports indicate that TDZ may act through modulation of the endogenous plant growth regulators, either directly or as a result of induced stress. The other possibilities include the modification in cell membranes, energy levels, nutrient uptake, or nutrient assimilation. In this review, several of these possibilities are presented and discussed in light of recently published studies on characterization of TDZ-induced morphogenic effects.

We have developed a new plant vector system for repeated transformation (called MAT for multi-autotransformation) in which a chimeric ipt gene, inserted into the transposable element Ac, is used as a selectable marker for transformation. Selectable marker genes conferring antibiotic or herbicide resistance, used to introduce economically valuable genes into crop plants, have three major problems: (i) the selective agents have negative effects on proliferation and differentiation of plant cells; (ii) there is uncertainty regarding the environmental impact of many selectable marker genes; (iii) it is difficult to perform recurrent transformations using the same selectable marker to pyramid desirable genes. The MAT vector system containing the ipt gene and the Ac element is designed to overcome these difficulties. When tobacco leaf segments were transformed and selected, subsequent excision of the modified Ac produced marker-free transgenic tobacco plants without sexual crosses or seed production. In addition, the chimeric ipt gene could be visually used as a selectable marker for transformation of hybrid aspen (Populus sieboldii x Populus grandidentata). The chimeric ipt gene, therefore, is an attractive alternative to the most widely used selectable marker genes. The MAT vector system provides a promising way to shorten breeding time for genetically engineered crops. This method could be particularly valuable for fruit and forest trees, for which long generation times are a more significant barrier to breeding and genetic analysis

Roots of taro (Colocasia esculenta [L.] Schott cvs Bun-long and Lehua maoli) exuded increasing concentrations of oxalate with increasing Al stress. This exudation was a specific response to excess Al and not to P deficiency. Addition of oxalate to Al-containing solutions ameliorated the toxic effect of Al