Differential growth and shape formation in plant organs (PNAS)

This paper is kind of fun because it explores plant leaf and petal shape from an engineering perspective, identifying “fundamental mechanistic insights into how nature invokes mechanics in the evolution of commonly found shapes in plant organs by differential growth.” For each organ, the authors empirically determine growth strain profiles and the parameters β and n, which correlate with the four types of configurations (twisting, helical twisting, saddle bending, and edge waving). They then can replicate these configurations using polyacrylamide hydrogels with embedded strings, in which “growth” and therefore strain is controlled by oxygen-inhibition of polymerization. The authors observe that in addition to contributing to our understanding of plant organ development, their work, “points to pathways to create bioinspired complex 3D shapes that could find applications in such areas as tissue engineering, flexible electronics, and soft robotics.” (Summary by Mary Williams) Proc. Natl. Acad. Sci. USA  10.1073/pnas.1811296115