A microtubule-mediated mechanical feedback controls leaf blade development in three dimensions

Many plant species have thin leaf blades, which is an important adaptation that optimizes the exchanges with the environment. Here, we provide evidence that their three-dimensional geometry is governed by microtubule alignment along mechanical stress patterns in internal walls. Depending on the primary shape of the primordium, this process has the potential to amplify an initial degree of flatness, or promote the formation of nearly axisymmetric, mostly elongating organs, such as stems and roots. This mechanism may explain leaf evolution from branches, which is alternative to Zimmermann’s influential, but widely questioned, telome theory. One Sentence Summary Mechanical feedback controls leaf development in three dimensions