Vessel areas and distributions in Eucalyptus globulus and E. nitens vary in a consistent, significant and predictable way from pith to bark and within annual rings. Trends in vessel areas and distributions can be quantified despite the presence of indistinct annual rings and false rings. There is evidence of a vessel free area in first earlywood in E. nitens in which fibre properties are predictably different. At 5% height the vessel free area in the 1991 and 1992 annual rings is 13% and 1O% respectively.

The genetic manipulation of perennial woody tree species presents a range of additional challenges compared to that of annual weedy crop species. These include long generation times and reproductive cycle, the heterogeneity of plants under investigation and, when investigating wood properties, a number of physical and biochemical limitations to microscopical and molecular experimentation. The use of in vitro wood formation systems for molecular studies and Agrobacterium-mediated introduction of transgenes overcomes many of these obstacles. Using a commercially relevant Eucalyptus species as model organism, we demonstrate here that in vitro wood formation systems can be readily employed to introduce transgenes into growing wood-producing tissue, initially leading to frequent transient gene expression in a range of cell types. Stable transformation events were observed as sectors of transformed tissue derived from primary transformation events in individual cells. The usefulness of such systems for the analysis of gene function during the process of wood formation and wood quality determination, as well as for constructing developmental fate maps of cambial derivatives, is discussed.

Secondary stem growth in trees and associated wood formation are significant both from biological and commercial perspectives. However, relatively little is known about the molecular control that governs their development. This is in part due to physical, resource and time limitations often associated with the study of secondary growth processes. A number of in vitro techniques have been used involving either plant part or whole plant system in both woody and non-woody plant species. However, questions about their applicability for the study of secondary stem growth processes, the recalcitrance of certain species and labor intensity are often prohibitive for medium to high throughput applications. Also, when looking at secondary stem development and wood formation the specific traits under investigation might only become measurable late in a tree's lifecycle after several years of growth. In addressing these challenges alternative in vivo protocols have been developed, named Induced Somatic Sector Analysis, which involve the creation of transgenic somatic tissue sectors directly in the plant's secondary stem. The aim of this protocol is to provide an efficient, easy and relatively fast means to create transgenic secondary plant tissue for gene and promoter functional characterization that can be utilized in a range of tree species. Results presented here show that transgenic secondary stem sectors can be created in all live tissues and cell types in secondary stems of a variety of tree species and that wood morphological traits as well as promoter expression patterns in secondary stems can be readily assessed facilitating medium to high throughput functional characterization.

Secondary stem growth in trees and associated wood formation are significant both from biological and commercial perspectives. However, relatively little is known about the molecular control that governs their development. This is in part due to physical, resource and time limitations often associated with the study of secondary growth processes. A number of in vitro techniques have been used involving either plant part or whole plant system in both woody and non-woody plant species. However, questions about their applicability for the study of secondary stem growth processes, the recalcitrance of certain species and labor intensity are often prohibitive for medium to high throughput applications. Also, when looking at secondary stem development and wood formation the specific traits under investigation might only become measurable late in a tree's lifecycle after several years of growth. In addressing these challenges alternative in vivo protocols have been developed, named Induced Somatic Sector Analysis, which involve the creation of transgenic somatic tissue sectors directly in the plant's secondary stem. The aim of this protocol is to provide an efficient, easy and relatively fast means to create transgenic secondary plant tissue for gene and promoter functional characterization that can be utilized in a range of tree species. Results presented here show that transgenic secondary stem sectors can be created in all live tissues and cell types in secondary stems of a variety of tree species and that wood morphological traits as well as promoter expression patterns in secondary stems can be readily assessed facilitating medium to high throughput functional characterization.