RESUMEN
Biofuels provide a potential route to avoiding the global political instability and environmental issues that arise from reliance on petroleum. Currently, most biofuel is in the form of ethanol generated from starch or sugar, but this can meet only a limited fraction of global fuel requirements. Conversion of cellulosic biomass, which is both abundant and renewable, is a promising alternative. However, the cellulases and pretreatment processes involved are very expensive. Genetically engineering plants to produce cellulases and hemicellulases, and to reduce the need for pretreatment processes through lignin modification, are promising paths to solving this problem, together with other strategies, such as increasing plant polysaccharide content and overall biomass.
Asunto(s)
Celulasa/biosíntesis , Celulasa/química , Celulosa/química , Etanol/metabolismo , Ingeniería Genética/métodos , Plantas/genética , Biotecnología , Pared Celular/química , Celulasa/genética , Plantas/enzimologíaRESUMEN
Oat (Avena sativa L.), a worldwide temperate cereal crop, is deficient in tolerance to osmotic stress due to drought and/or salinity. To genetically transform the available commercial oat cultivars, a genotype-independent and efficient regeneration system from shoot apical meristems was developed using four oat cultivars: Prairie, Porter, Ogle, and Pacer. All these oat cultivars generated a genotype-independent in vitro differentiated multiple shoots from shoot apical meristems at a high frequency. Using this system, three oat cultivars were genetically co-transformed with pBY520 (containing hva1 and bar) and pAct1-D (containing gus) using biolistic trade mark bombardment. Transgenic plants were selected and regenerated using herbicide resistance and GUS as a marker. Molecular and biochemical analyses of putative transgenic plants confirmed the co-integration of hva1 and bar genes with a frequency of 100%, and 61.6% of the transgenic plants carried all three genes (hva1, bar and gus). Further analyses of R0, R1, and R2 progenies confirmed stable integration, expression, and Mendalian inheritance for all transgenes. Histochemical analysis of GUS protein in transgenic plants showed a high level of GUS expression in vascular tissues and in the pollen grains of mature flowers. Immunochemical analysis of transgenic plants indicated a constitutive expression of hva1 at all developmental stages. However, the level of HVA1 was higher during the early seedling stages. The characteristic of HVA1 expression for osmotic tolerance in transgenic oat progeny was analyzed in vitro as well as in vivo. Transgenic plants exhibited significantly (P<0.05) increased tolerance to stress conditions than non-transgenic control plants. The symptoms of wilting or death of leaves as observed in 80% of non-transgenic plants due to osmotic stress was delayed and detected only in less than 10% of trans-genic plants. These observations confirmed the characteristic of HVA1 protein as providing or enhancing the osmotic tolerance in transgenic plants against salinity and possible water-deficiency stress conditions.
Asunto(s)
Avena/genética , Avena/metabolismo , Técnicas de Transferencia de Gen , Estrés Fisiológico , Transformación Genética , Avena/efectos de los fármacos , Fenómenos Bioquímicos , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Presión Osmótica , Proteínas de Plantas/genética , Plantas Modificadas Genéticamente , Sales (Química)/farmacología , Estrés Fisiológico/genética , Estrés Fisiológico/fisiología , Transgenes/genética , Agua/metabolismoRESUMEN
FLOWERING LOCUS C (FLC), a gene from Arabidopsis thaliana (L.) Heynh. that acts as a flowering repressor, was expressed in tobacco (Nicotiana tabacum L. 'Samsun'). Five putative transgenic lines were selected and examined for the presence of FLC. Genomic DNA and total RNA were isolated from the Leaves and used for polymerase chain reaction (PCR) and RNA blot analysis, respectively. Both DNA and RNA tests confirmed the integration and transcription of FLC in all five Lines and their T1 progenies. Transgenic plants in one Line showed an average of 36 d delay in flowering time compared to control plants, and the overall mean for all lines was 14 d. Transgenic plants also displayed increased leaf size and biomass yield and reduced height at flowering time. It is important to note that the delay in flowering might have been caused by a slower rate of leaf initiation (i.e. nodes/day) rather than by a change in the flowering mechanism itself.