Cell Adhesion and Fate Determination in Physcomitrella Patens

University Of Louisville Research Foundation Inc, Louisville KY

Investigators

Abstract

One of the key milestones in the history of life on earth was the colonization of land by plants. To accomplish this feat, plants had to adapt to the much harsher terrestrial environment in a variety of ways, including making specialized structures for anchoring in soil, gathering sunlight, and reproducing, as well as being able to sense and respond to rapidly changing environmental conditions. How early plants were able to do this remains largely unknown. The moss Physcomitrella patens is an excellent species in which to study plant adaption to land, since mosses are among the earliest-arising land plants. P. patens also has a variety of properties that make it amenable to scientific study, including its small size, transparent cells, small amount of genetic material, ease of growth in the laboratory, and ease of manipulation using molecular tools. Moss lines have been developed that harbor mutations causing the plants to revert to single-celled organisms resembling green algae, the progenitor of land plants. These plants also are able to withstand dehydrating conditions better than normal moss plants. Studies of these mutants will give clues into how normal development of moss proceeds, but also what mechanisms early plants used to adapt to land. These studies also have implications for 1) developing crops that are better able to withstand drought, and 2) developing algae lines to be used in biofuel production that might be easier to harvest, by engineering individual algae cells that will stick together when prompted. The moss mutants that will be examined are defective in protein prenylation, which is a post-translational modification that adds a lipid group to particular target proteins. This lipid group plays a role in targeting the protein to membranes and in protein-protein interactions. It was previously found that prenylation deficiencies in moss resulted in a lack of cell adhesion after cell division, along with a complete lack of cell differentiation. These moss mutants were also more sensitive to abscisic acid, which resulted in higher survivability under dehydrating conditions. The goals of the current project are threefold: 1) to generate additional mutants defective in various types of protein prenylation, 2) further determine the functional roles of prenylation in cell adhesion, cell fate determination, cell differentiation, cell polarity, and hormone responses, and 3) identify and examine the functional role of key prenylation target proteins in mediating cell adhesion and developmental processes. Studies of prenylation in moss will advance our understanding of the genetic and molecular basis of many important plant processes of broad scientific interest. This project will provide training in a wide variety of experimental techniques, and will include extensive participation by students, especially those from groups underrepresented in the sciences.