Universiteit Leiden

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Research project

The role of auxin in somatic embryogenesis

What is the role of auxin in the initiation and process of somatic embryogenesis?

Duration
2011  -   2019
Contact
Remko Offringa
Funding
NWO Building Blocks Of Life NWO Building Blocks Of Life
 
NWO ALW -TTI-Green Genetics: NWO ALW -TTI-Green Genetics:
Partners

In plants, embryogenesis usually takes place in the seed after egg and sperm fusion, however this process can also be induced in vitro, either from unfertilized gametophytic cells or from the cells of vegetative tissue explants.

In plants, embryogenesis usually takes place in the seed after egg and sperm fusion, however this process can also be induced in vitro, either from unfertilized gametophytic cells or from the cells of vegetative tissue explants. Somatic embryogenesis (SE), in which embryos are derived from vegetative cells of the plant, is most commonly induced by exposing explants to stress conditions and/or exogenous growth regulators. However, SE can also be induced in planta on seedling cotyledons or shoot apical meristems by overexpression of specific transcription factors, such as BABYBOOM (BBM), LEAFY COTYLEDON 1 (LEC1), or WUSCHEL (WUS). There is considerable interest in somatic embryogenesis, both as a clonal propagation tool for the green sector and as a model system for understanding plant cell totipotency. Historically more emphasis has been placed on achieving and optimising somatic embryo (SE) production in different species than on understanding the mechanism underlying SE formation. The few mechanistic studies have used "static" approaches, which has made it difficult to establish causal relationships between the observed changes and the developmental fate of individual cells. In the last decade, significant progress has been made in developing Arabidopsis as a model for studies on SE. Still, there are very large gaps in our knowledge with respect to the dynamic steps needed to convert a differentiated cell into a SE.

We are using a combination of cell biology, physiology and molecular and genetic approaches to identify these steps during arabidopsis somatic embryo development, and in particular, the role of auxin biosynthesis, transport and signalling in this process. We focus our efforts on the earliest stages of SE induction by the auxin analog 2,4-D in vitro, and use these results as a framework to understand the relationship between this process and gene-mediated SE induction in planta.

Publications

  • Soriano, M., Li, H., Jacquard, C., Angenent, G.C., Krochko, J., Offringa, R., Boutilier, K. (2014) Plasticity in cell division patterns and auxin transport dependency during in vitro embryogenesis in Brassica napus. Plant Cell 26, 2568-2581.
  • Supena, E.D.J., Winarto, B., Riksen, T., Dubas, E., van Lammeren, A., Offringa, R., Boutilier, K. and Custers, J. (2008) Regeneration of zygotic-like microspore-derived embryos suggests an important role for the suspensor in early embryo patterning. J. Exp. Bot. 59, 803-814.
  • Friml, J., Vieten, A., Sauer, M., Weijers, D., Schwarz, H., Hamann, T., Offringa, R. and Jurgens, G. (2003). Efflux-dependent auxin gradients establish the apical-basal axis of Arabidopsis. Nature 426, 147-153.
  • Weijers, D., van Hamburg, J.P., van Rijn, E., Hooykaas, P.J., and Offringa, R. (2003). Diphtheria toxin-mediated cell ablation reveals interregional communication during Arabidopsis seed development. Plant Physiol. 133, 1882-1892.
  • Boutilier, K., Offringa, R., Sharma, V. K., Kieft, H., Ouellet, T., Zhang, L., Hattori, J., Liu, C. M., van Lammeren, A. A., Miki, B. L. et al. (2002). Ectopic expression of BABY BOOM triggers a conversion from vegetative to embryonic growth. Plant Cell 14, 1737-1749.
Individual (left panel) and fused (middle panel) somatic embryos induced on an immature zygotic Arabidopsis embryo by 2,4-D treatment. Right panel shows 2,4-D-induced globular structures expressing the pWOX2-GFP embryo marker.

Connection with other research

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