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ABSTRACT This study aimed to evaluate the effect of factors that may affect the genetic transformation of cotiledonary explants of Eucalyptus saligna mediated by EHA105 strain of Agrobacterium tumefaciens. The vector pBI121 carrying gus gene under control of 35S CaMV promoter was used. The effect of the following factors was evaluated: explant pre-culture, use of different antibiotics and presence of acetosyringone (AS) in co-culture media. An antioxidant solution was also used during excision, containing ascorbic acid (250mg.L-1), citric acid (25mg.L-1) and PVP-40 (1g.L-1). Pre-culture of the explants before the co-culture with bacteria was done over a 4-day period in MS culture medium supplemented with 4.4µM BAP and 2.7ìM NAA. After theco-culture period, three concentrations of kanamycin (12.5;25 and 50mg.L-1) combined with 300mg.L-1 Augmentin® in the culture medium were tested The influence of the antibiotic was also evaluated by keeping the explants in a medium containing 50mg.L-1 Km and 300mg.L-1 Augmentin® or 500mg.L-1 cefotaxime. It was concluded that Augmentin® stimulates organogenesis, that a Km concentration of 12.5mg.L-1 allows selection of explants transformed with gus gene and, finally, the addition of AS (50ìM) to the liquid and solid co-culture media has a positive effect on gus gene expression. Moreover, the use of an antioxidant solution during cotyledon excision is dispensable and the pre-culture of the explants has no effect on bud regeneration or gus gene expression. A transformation efficiency of 1.5% was reached.

http://dx.doi.org/10.5902/1980509814572The aims of this research were to evaluate different culture media for indirect organogenesis and shoot multiplication of Eucalyptus benthamii x Eucalyptus dunnii. For organogenesis, leaf explants were used to test the following treatments: two culture media (MS N/2 and JADS) supplemented with 0.1 μM 1-naphthaleneacetic acid (NAA) and thidiazuron (TDZ) (0.1 or 0.5 μM), with or without PVP- 40 (250 mg L-1). The percentage of oxidized explants, callus forming explants, explants with anthocyanin, buds, shoots and the shoot number per explant were evaluated. In the multiplication experiment, isolated shoots were cultivated in MS, JADS and WPM media, all supplemented with 1.11 μM BAP. Four subcultures were carried out every 28 days. In every subculture the explant oxidation, partial or total leaf chlorosis, fresh mass and mean number of shoot per explant were evaluated. The MS N/2 medium supplemented with 0.1 μM NAA and 0.5 μM TDZ promoted the highest rate of organogenesis (8.3%) and the culture media MS supplemented with 1.11 μM BAP the multiplication rate was higher than in the other media, in the first and the second subcultures (9.28 and 9.24, respectively), without differences between the three media in the following subcultures.

The aims of this research were to evaluate different culture media for indirect organogenesis and shoot multiplication of Eucalyptus benthamii x Eucalyptus dunnii . For organogenesis, leaf explants were used to test the following treatments: two culture media (MS N/2 and JADS) supplemented with 0.1 μM 1-naphthaleneacetic acid (NAA) and thidiazuron (TDZ) (0.1 or 0.5 μ M), with or without PVP- 40 (250 mg L -1 ). The percentage of oxidized explants, callus forming explants, explants with anthocyanin,buds, shoots and the shoot number per explant were evaluated. In the multiplication experiment, isolated shoots were cultivated in MS, JADS and WPM media, all supplemented with 1.11 μ M BAP. Four subcultures were carried out every 28 days. In every subculture the explant oxidation, partial or total leaf chlorosis, fresh mass and mean number of shoot per explant were evaluated. The MS N/2 medium supplemented with 0.1 μM NAA and 0.5 μM TDZ promoted the highest rate of organogenesis (8.3%) and the culture media MS supplemented with 1.11 μ M BAP the multiplication rate was higher than in the other media, in the first and the second subcultures (9.28 and 9.24, respectively), without differences between the three media in the following subcultures.

Abstract: Salinity and water deficit limit the productivity of several crops; thus, studies related to the genetic transformation of seeds in a model plant, such as tobacco, can be an alternative to minimize negative impacts caused by environmental conditions. The purpose of this work was to evaluate the tolerance to osmotic stress of seeds from genetically transformed tobacco plants, with the introduction of the proline-synthesizer gene (p5csf129a), under salinity and water deficit conditions. To do so, five events with differences in proline content were selected, ranging from 0.70 to 10.47 µmoles.g-1 of fresh mass. The used saline concentrations were: zero (distilled water); 50; 100; 150 and 200 mmol.L-1 of NaCl, whereas for the water deficit, simulated with PEG 6000, the following osmotic potentials were used: zero (distilled water); -0.2; -0.4; -0.6 and -0.8 MPa. Each tested treatment was evaluated through germination, first germination count and germination speed index tests. It is possible to conclude that seeds from genetically transformed tobacco plants with overexpression of the gene p5csf129a, a proline synthesizer, are more tolerant to osmotic stresses. Tabacco seeds with a proline content of 10.47 µmol.g-1 showed a better perfomance, revealing higher physiological potential.