Group leader: Miltos Tsiantis

Research project:

The role of regulated growth repression in shaping plant organ form.

How regulated growth produces organ growth and form is a major question in biology. Previous work has shown that local expression of the Reduced Complexity growth repressing protein has a key role in sculpting growth of complex leaves like those of Cardamine hirsuta -a relative of the simple leafed A. thaliana plant (Bhatia et al., 2021; Vlad et al., 2014; Vuolo et al., 2016). This action is important for generation of species-specific leaf forms because RCO is expressed in discrete foci along the margin of Cardamine hirsuta leaves where it represses growth, while the genome of Arabidopsis thaliana does not contain an RCO gene. Conversely, introduction of RCO in Arabidopsis as a transgene is sufficient to recapitulate its growth-repressive function and cause a complex leaf phenotype, demonstrating the significance of this gene for leaf shape diversity. However, the precise cellular parameters of RCO-mediated growth repression are unknown and how the cellular mode of RCO action relates to that of other proteins repressing growth is unclear. In this project, we will work to resolve these issues using a combination of genetics, advanced imaging and computational modelling. Specifically, we will use a CRE-LOX system to generate sectors of RCO and other growth repressors in Arabidopsis leaves, and by using time-lapse imaging, we will measure effects on the amount, direction and duration of cellular growth. We will then use this information to generate computational models of leaf form that will be constructed in the Morphomechanx framework (https://morphographx.org/morphomechanx/) which uses the Finite Element method. The project will be carried out at MPIPZ and will involve secondments to JIC, where the computational modelling group of Dr Richard Smith is based.

References
Bhatia, N., Runions, A., and Tsiantis, M. (2021). Leaf Shape Diversity: From Genetic Modules to Computational Models. Annu Rev Plant Biol 72, 325-356.
Vlad, D., Kierzkowski, D., Rast, M.I., Vuolo, F., Dello Ioio, R., Galinha, C., Gan, X., Hajheidari, M., Hay, A., Smith, R.S., et al. (2014). Leaf Shape Evolution Through Duplication, Regulatory Diversification, and Loss of a Homeobox Gene. Science (New York, NY) 343, 780-783.
Vuolo, F., Mentink, R.A., Hajheidari, M., Bailey, C.D., Filatov, D.A., and Tsiantis, M. (2016). Coupled enhancer and coding sequence evolution of a homeobox gene shaped leaf diversity. Genes & development 30, 2370-2375.

Key publication

Kierzkowski et al., 2019, Cell 177, 1–14. https://doi.org/10.1016/j.cell.2019.05.011

Potential collaborations with other research groups

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