PubMed · 2026-06-22
Scientists have mapped the genetic and physical rules that make leaves grow flat rather than curled or domed — a property that turns out to require precise teamwork among genes, cell-wall chemistry, and microscopic fiber alignment.
Opposing gene sets on the upper and lower leaf surfaces create differential growth forces; disrupting this balance causes laminar buckling or doming.
Auxin (a plant hormone) accumulates at the leaf's side margins to activate WOX genes, carving out the growth zone responsible for the leaf blade expanding outward.
Cortical microtubules — microscopic protein tubes inside cells — orient perpendicular to the top-bottom axis to direct cellulose fiber deposition, physically constraining how and where the leaf can stretch.
