Dr. Maura Zimmermann (postdoctoral associate, Roeder Lab) will present“Mechanics of cell growth of flat leaves”. Join us in Weill Hall 224 at 3:30pm on Wednesday, May 21st.

Abstract: Relatively flat shapes are widespread in multicellular organisms, such as animal epithelia, plant leaves, fly wings, lichen thalli, and flatworms. Growing flat can have different benefits, for example flat leaves are considered optimal for photosynthesis and gas exchange, while fly wings need to be flat for flight. However, keeping the tissue flat as it grows is difficult, since differences in growth between cells can generate growth conflicts causing the tissue to bend. For example, leaves have areas of fast-growing and slow-growing cells occurring simultaneously, which we would expect to create growth conflicts, causing tissue to bend or ripple. However, leaves remain flat, or mostly flat, because cell growth is coordinated across the width of the leaf blade to mitigate conflicts. To determine how growth is coordinated to maintain leaf flatness, I have identified the det2-1 mutant with disrupted leaf flatness is in Arabidopsis thaliana. DET2 encodes a brassinosteroid biosynthesis enzyme and det2-1 mutants display a dwarfed phenotype, with small, round, wrinkled leaves with smaller cells. Brassinosteroids are a plant steroid hormone that regulates plant growth. Preliminary data indicates that growth between cell layers of the leaf is uncoordinated in the det2-1 mutant. Additionally, application of brassinosteroid to other mutants with a wrinkled leaf phenotype rescues the phenotype and results in a flatter leaf. I aim to use these mutants in conjunction with det2 to determine how brassinosteroids coordinate cell growth to maintain organ flatness during development.