Genes are known to control the shape of biological structures, like flowers, hearts, and limbs, yet how they do this is poorly understood. The results suggest that genetic control of tissue polarity organisers has played a key role in the development and evolution of shape. In particular, genetic control of tissue polarity organisers at ventral petal junctions and distal boundaries allows both the shape and growth field of the flower to be accounted for in wild type and mutants. However, the data can be readily explained by a model in which dorsoventral genes also modify organisers of tissue polarity. Models in which dorsoventral genes only influence specified growth rates do not fully account for the observed growth fields and shapes. The action of these genes can be modelled by assuming they modulate specified growth rates parallel or perpendicular to local orientations, established by a few key organisers of tissue polarity. This growth field is under the control of several dorsoventral genes that influence flower shape. Using the Snapdragon ( Antirrhinum) flower as an example, we show how shape development reflects local rates and orientations of tissue growth that vary spatially and temporally to form a dynamic growth field. Here we show how a combination of growth analysis, molecular genetics, and modelling can be used to dissect the factors contributing to shape. Distinguishing between these possibilities has been difficult because of interactions between patterns, orientations, and mechanical constraints during growth. In principle, genes may control shape by modifying local rates and/or orientations of deformation.
The mechanisms by which genes control organ shape are poorly understood.
0 kommentar(er)
