**Acknowledgements**

line collections. Finally, in many studies *Arabidopsis* was also postulated as a perfect plant for

Although the vascularization and regeneration in *Arabidopsis* have been previously analyzed [3, 81], the role of vascular cambium in these processes has never been addressed. Only just modified and established method to obtain stems with closed vascular cambium rings and some typical features mimicking vascular tissue in trees [7, 51], such as secondary rays and intrusively growing cambial cells or tracheids—unusual example of tracheary elements found in woody plants—gives infinite possibilities to analyze secondary vascular tissue development and provides decisive advantage over previous approaches with the use of *Arabidopsis* stems. This strategy is particularly suited to elucidate different molecular mechanisms and other molecular components involved in auxin-mediated responses, canalization of auxin flow, and cellular polarity, underlying determination of plant devel-

The availability of numerous genetic and molecular tools in *Arabidopsis* will provide clarifying picture of the process of vasculature formation as well as reconstruction after wounding and decisively extend the knowledge on molecular control of spatiotemporal vasculature patterning and regeneration both in vivo and in vitro. Resolving the involvement, the mechanism of canalization process will contribute to explain molecular mechanisms involved in vasculature

Specifically manipulated *Arabidopsis* represents a good system for the analysis of vascularization machinery that typically occurs in trees. Obtained results revealed that this process is accompanied with cellular events following cambium ontogenesis, xylem formation, and regeneration: (1) elevated auxin concentration in tissues, (2) new polarity establishment, (3) reposition of PIN1 proteins at plasma membranes of differentiating cells, (4) cellular divi-

Knowledge about the molecular mechanisms regulating vascular tissue development in trees is incomplete, and such studies can take full practical advantages from a recently proposed new approach. Temporal analysis and experiments in trees are hampered mainly because of variability in environmental conditions, their long life cycle, and restricted amount of trans-

Currently, new insights into the vascular tissue formation problematics can be obtained by using *Arabidopsis thaliana* (L.) Heynh. This modest plant commonly used as a genetic model can be also modified to become a perfect experimental "tree-like" model, with a closed ring of functional cambium and secondary vascular tissues with complexity of phenotype features fully comparable to woody plants. This new approach promises to identify additional genetic and molecular components involved in vascular tissue functioning, including the insights into the role of cambial cells in this process in woody plants. Extensive studies with the use of

sions, and finally (5) cambium and vascular tissue development or regeneration.

secondary growth analysis [37–39, 44, 45, 50, 102, 103].

regeneration and provide a useful model for further studies.

opmental plasticity.

132 Plant Engineering

**7. Conclusions**

genic lines and mutants available.

This publication was funded by the European Research Council under the European Union's Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement n° 282300.
