RESUMO
BACKGROUND: Virus-free sugarcane is difficult to achieve due to the multiple vegetative propagation cycles employed commercially. In vitro culture using small (1 mm) meristematic shoot tips has eliminated viruses but survival is low with small explants. OBJECTIVE: Droplet-Vitrification (D-V) and V-Cryoplate protocols were investigated for the elimination of Sugarcane mosaic virus (SCMV) from large (c. 3 mm) in vitro-derived shoot tips. MATERIALS AND METHODS: Shoot tips excised from NCo376 and N19 cultivars were exposed to both cryogenic procedures. Virus indexing by RT-qPCR was performed 16 weeks after recovery. RESULTS: Explants exposed to cryo-treatments that recovered and multiplied was 30-92%, while at least 90% of control explants regenerated. No virus was detected in multiplied shoots from either cultivar after D-V and liquid nitrogen immersion. In NCo376, virus was eliminated after D-V without cooling. CONCLUSION: The preliminary findings suggest that cryotherapy and/or osmotherapy are viable options for SCMV removal from infected plants.
Assuntos
Congelamento , Doenças das Plantas/prevenção & controle , Doenças das Plantas/virologia , Potyvirus , Saccharum , Brotos de Planta/virologia , Saccharum/virologia , Técnicas de Cultura de TecidosRESUMO
KEY MESSAGE: Sugarcane lines transformed with an alanine aminotransferase gene demonstrated an improved nitrogen use efficiency compared with untransformed controls in a pot trial under low nitrogen conditions.
Assuntos
Alanina Transaminase/metabolismo , Nitrogênio/metabolismo , Saccharum/metabolismo , Alanina Transaminase/genética , Fenótipo , Folhas de Planta/genética , Folhas de Planta/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Raízes de Plantas/genética , Raízes de Plantas/metabolismo , Brotos de Planta/genética , Brotos de Planta/metabolismo , Plantas Geneticamente Modificadas , Saccharum/genéticaRESUMO
A rapid in vitro protocol using direct somatic embryogenesis and microprojectile bombardment was investigated to establish the developmental phases most suitable for efficient sugarcane transformation. Immature leaf roll disc explants with and without pre-emergent inflorescence tissue were compared. It was shown that for effective transformation to occur, explants should be cultured for several days to allow initiation of embryo development prior to bombardment. Leaf roll discs with pre-emergent inflorescences showed a higher degree of embryogenic competence than non-flowering explants, and transformation efficiency was higher when explants containing floral initials were bombarded. Despite the occurrence of high numbers of phenotypically negative plants, combining the use of inflorescent leaf roll discs with direct embryogenic regeneration has the potential to improve the speed and efficiency of transgenesis in sugarcane.
Assuntos
DNA de Plantas/metabolismo , Desenvolvimento Embrionário , Folhas de Planta/embriologia , Saccharum/embriologia , Transformação Genética , Técnicas de Transferência de Genes , Genótipo , Fenótipo , Plantas Geneticamente Modificadas , Saccharum/genética , Fatores de TempoRESUMO
A cryIA(c) gene was cloned from a native Bacillus thuringiensis strain showing activity against the sugarcane borer, Eldana saccharina. The sequence of the cloned gene was very similar to that of the B. thuringiensis subsp. kurstaki HD-73 cryIA(c) gene. The gene was introduced into an isolate of Pseudomonas fluorescens, capable of colonizing sugarcane, on two broad-host-range plasmids, pDER405 and pKT240, having copy numbers of 13 and 28, respectively. By using the Omegon-Km vector, the cry gene was introduced into the chromosome of P. fluorescens isolate 14. Bioassays on eldana larvae showed that the strain carrying the gene integrated into the chromosome was as toxic as one carrying it on pKT240. Glasshouse trials indicated that sugarcane treated with P. fluorescens 14::Omegon-Km-cry were more resistant to eldana damage than untreated sugarcane was.