Thanks to Anne Knowlton and Current Biology for working with us get the first paper from Jeremy Solly’s PhD out, now online here :-).
In it we address the question of how plant shape arises in an ancient planar growth form, the liverwort thallus. We have found that growth rate variation is sufficient to determine thallus shape, and that auxin production in the notch region is likely to pattern growth rate variation.
In contrast, planar shapes in flowering plants emerge by differential growth oriented with respect to each cell’s internal compass, or polarity. The results raise questions about the roles of polarity in liverwort thalli and how the mechanisms that determine plant shape have changed through evolution.
Comparing liverwort and flowering plant development spans the broadest evolutionary distance in land plants, so if we identify shared mechanisms for shape in the future, they are likely to have broad relevance to future efforts to engineer shape.