429 / 2019-01-28 14:44:19

Maintaining flattened laminar structure requires balanced growth on two sides of the organ

organ morphology, plant development, sepal, AS2, live-imaging

全体主题 > Development

To form a flattened surface in organs is critical for plants to maximize light capture during photosynthesis. The mechanisms on developing a flattened laminar structure in plants are poorly understood. We have isolated an Arabidopsis mutant with abnormal planar growth. The mutant forms up-curved leaves and a ruffled abaxial sepal epidermis, suggesting an imbalance of growth occurs between the abaxial and adaxial sides of the organs. We focus on the sepal as a model to study tissue laminar growth. Through live imaging we tracked the cellular growth on the abaxial sepal epidermis, and found that the mutant sepal phenotype was caused mainly by excess growth on the abaxial epidermis. We built a mechanics model to simulate the ruffle formation in the mutant sepal. The model revealed that with excess growth and lower elastic modulus the abaxial side would result in buckling of the epidermis and reproduce the mutant phenotype. We tested the model by either decreasing growth or increasing stiffness on the abaxial sepal epidermis and both modifications suppressed the ruffled sepal phenotype. Therefore, development of a flattened laminar structure in plants requires balanced growth on two sides of the organ. The mutant was caused by an ectopic expression of the ASYMMETRIC LEAVES 2 (AS2) gene on the abaxial epidermis. We are currently further elaborating the mechanisms on how ectopic AS2 expression affects growth balance between two sides of the sepal.