Snapping movements in oat seed dispersal

events hall

Prof. Rivka Elbaum

28.07.2022

David Wang Auditorium, 3rd floor Dalia Meidan Bldg.

14:30

As non-motile organisms, plants develop means to spread their seed progeny. One very intriguing mechanism involves movements of the dispersal unit that carry the seed, based on the diurnal changes in air humidity. These hygroscopic movements are programmed into the material from which the plant tissue is made, constructing a small wooden self-propagating machine. In our research, we study the built of these smallish machines that are designed to send plant seeds to a safe germination location.

In my talk, I will present the basic bending, twisting, and coiling movements programmed into the plant structure, and show the material arrangements creating these movements. I will then present our recent work on the seed dispersal units of wild oats. The units carry two elongated beams that twist and coil to form prototypical two-link robotic arms. Based on nano-to-micro structure analyses the bending and twisting hygroscopic movements are explained. The coordinated movements of two sister beam attached to one dispersal unit were followed. Our work shows that sister beams intersect at least twice every wetting-drying cycle. Once the beams cross each other, epidermal silica hairs are suggested to lock subsequent movements, resulting in stress accumulation. Sudden release of the interlocked beams induces a jump of the dispersal unit, changing its movement direction. Our findings propose a new role to epidermis silica hairs and a new facet of wild oat seed dispersion.

Host: Asst. Prof. Noy Cohen