Penium margaritaceum as a Model Organism for Cell Wall Analysis of Expanding Plant Cells

Abstract

The growth of a plant cell encompasses a complex set of subcellular components interacting in a highly coordinated fashion. Ultimately, these activities create specific cell wall structural domains that regulate the prime force of expansion, internally generated turgor pressure. The precise organization of the polymeric networks of the cell wall around the protoplast also contributes to the direction of growth, the shape of the cell, and the proper positioning of the cell in a tissue. In essence, plant cell expansion represents the foundation of development. Most studies of plant cell expansion have focused primarily upon late divergent multicellular land plants and specialized cell types (e.g., pollen tubes, root hairs). Here, we describe a unicellular green alga, Penium margaritaceum (Penium), which can serve as a valuable model organism for understanding cell expansion and the underlying mechanics of the cell wall in a single plant cell.

The Penium margaritaceum Genome: Hallmarks of the Origins of Land Plants

“…To visualize starch, cell pellets were resuspended in growth medium and stained for 5 min with 1% v/v iodine then washed before imaging. Immunolabeling of cell wall pectin followed the protocol of Rydahl et al (2015) with the anti-HG monoclonal antibody, JIM5 (Knox et al, 1990).…”

Isolation and manipulation of protoplasts from the unicellular green alga Penium margaritaceum

“…This alga is a unique model organism in that it is unicellular, easy to culture and maintain in the laboratory, responds to external treatments, and its mechanism for depositing cell wall components during expansion and development may be monitored using various microscopy technologies. Furthermore, the subcellular machinery for the production of these wall components is elaborate and provides an effective system for the analysis of the roles of endomembrane trafficking, secretion and plasma membrane dynamics in plant cells [7,11,17].…”

“…Penium margaritaceum (Zygnematophyceae; Streptophyta) is a unicellular green alga that belongs to the charophycean green algae (CGA), or basal Streptophyta [1][2][3], i.e., the assemblage of extant green algae most closely related and ancestral to land plants [4,5]. This species has become increasingly valuable as a tool for studies of the primary cell wall of plants [6][7][8][9]. Penium has a simple geometric form consisting of an elongate cylinder with rounded edges, and produces only a primary cell wall that contains several of the polymers that are typically found in the cell walls of land plants, namely cellulose, pectins (homogalacturonan (HG) and rhamnogalacturonan I (RGI)) and proteoglycans [10,11].…”

Charophytes: Evolutionary Giants and Emerging Model Organisms

“…Over the past decade, the desmid, Penium margaritaceum , has also become a valuable model organism ( Domozych et al, 2009 , 2014 ; Sørensen et al, 2014 ; Rydahl et al, 2015 ; Worden et al, 2015 ). Unlike Micrasterias, Penium has a simple cylindrical shape, possesses only a primary cell wall and deposits wall polymers at two specific loci of the cell surface during expansion ( Domozych et al, 2011 ).…”

“…One of its main attributes is that it has wall polymers similar to those present in many land plants (e.g., cellulose, pectins, hemicelluloses) and that these polymers can be labeled with monoclonal antibodies. After labeling of live cells, these can be returned to culture where subsequent cell expansion and wall deposition events can be monitored ( Domozych et al, 2009 ; Rydahl et al, 2015 ). Penium is also easily maintained in the laboratory and its fast growth rate under precisely controlled conditions makes it an excellent specimen for large-scale concurrent microarray screenings of many chemical agents (by growth in multi-well plates) and for assessment of their specific effects on expansion/wall development ( Worden et al, 2015 ).…”