Plant Regeneration

Plants can regenerate new organs and even an entire copy of themselves after they are wounded, when they are placed in tissue culture, or as part of their normal developmental program. This developmental plasticity forms the basis for many practical breeding and propagation techniques, but also provides unique systems to understand how differentiated cells are induced to undergo cell fate changes. The ability of plant cells to regenerate is regulated at many different levels, from mechanical to physiological to epigenetic, but there are still many unanswered questions: what are the specific signals that induce plant cells to regenerate, how are these signals perceived, and how are translated into a specific type of regeneration?

Kim Boutilier’s group studies one type of plant regeneration, totipotency, which is the ability of a cell to develop into an embryo in the absence of fertilization. During sexual reproduction, plant embryos develop after fusion of the egg and sperm cell, but many plant cells can also develop into an embryo in the absence of fertilization. Asexual embryos can develop from vegetative tissues or gametophytic tissues like egg cells and pollen. We study different types of totipotency:

· Microspore embryogenesis: in vitro cultured immature pollen grains develop into embryos after an abiotic stress treatment. We are trying to understand how stress-induced changes in chromatin architecture and chromatin modifications induce pollen grains to become embryos and how pollen wall mechanics affect subsequent embryo development.

· Parthenogenesis: egg cells develop into haploid embryos in the seed or in tissue culture. We are trying to understand how pollen mutants like dmp and embryo identity transcription factors like BABY BOOM can trick the egg cell into developing into an embryo without fertilization.

· Somatic embryogenesis: in vitro cultured vegetative cells develop into embryos after treatment with the synthetic auxin 2,4-D. Why can somatic embryogenesis be efficiently induced in some genotypes, while other genotypes are non-responsive? We are investigating the transcriptional responses of different plant genotypes to 2,4-D to identify the factors that promote or inhibit totipotency.

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