Abstract

The evolution of 3-dimensional (3D) growth coincided with the colonization of land by plants approximately 470 million years ago. The acquisition of apical cells that could cleave in three planes, rather than just one or two, allowed plants to develop the characteristics required to successfully survive and reproduce on land (e.g., roots, vasculature, seeds). 3D growth is an invariable and fundamental feature of all land plants, and the diverse morphologies exhibited across the globe are a result of the differential regulation of 3D growth processes. Yet, we know very little about how 3D growth is regulated at the genetic level. In many plants, 3D growth is initiated during the first few divisions of the zygote, and therefore, the genetic basis cannot be dissected because mutants do not survive. However, in mosses, which are representatives of the earliest land plants, 3D shoot growth is preceded by a 2D filamentous phase that can be maintained indefinitely. Using forward genetics, we have isolated many developmental mutants that fail to establish and/or maintain 3D growth. This has been a powerful and unbiased approach that has enabled us to identify, and functionally characterize novel regulators of the 2D to 3D growth transition. In this talk, I will describe the identification and characterization of our recently generated ‘no gametophores’ mutants.