Modulacao da lenhificacao em Eucalyptus globulus e E. camaldulensis atraves da engenharia genetica.

Abstract

Genetic engineering opens new opportunities to control wood and pulp properties. When applied to modulating lignification, it may result in easier lignin removal during pulping, rendering this process more profitable and ecological. The objective of this work was to down regulate genes specific of lignin biosynthesis in Eucalyptus, one of world's most planted and economically important trees. We optimized a genetic transformation procedure for two E. globulus juvenile clones, using A. tumefaciens, and obtained transgenic plants carrying the cinnamyl alcohol dehydrogenase (CAD) gene in antisense orientation with an efficiency of 0.8%. This is the first report on the modulation of a lignification gene in Eucalyptus. Transformed E. camaldulensis plants were also analysed and exhibited a reduction of CAD activity up to 83%. However, after wood anatomical and chemical analysis and pulp yield determination, down regulated 10 months old trees didn't show improved properties for the paper pulp production. Therefore, Eucalyptus doesn't behave like model species regarding modulation of lignification, at least for young material. These results may be due to an alteration of CAD activity in the transformants during development, or to a residual CAD activity above the threshold level that triggers marked differences in lignin characteristics for this species. Future works are needed to confirm these results in a large population of adult transgenic trees.Available from Fundacao para a Ciencia e a Tecnologia, Servico de Informacao e Documentacao, Av. D. Carlos I, 126, 1249-074 Lisboa, Portugal / FCT - Fundação para o Ciência e a TecnologiaSIGLEPTPortuga