Plasmodesmata: function and diversity in plant intercellular communication. Preface.

Abstract

possess PD, which likely have a common evolutionary origin with the PD found in embryophytes (Raven 2005; Evkaikina et al. 2014). In the other classes of green algae, PD occur in some members of the Chlorophyceae and the Ulvophyceae (Raven 2005), but have not been reported in the Prasinophyceae and the Trebouxiophyceae. The Charophyceae, Chlorophyceae, and Ulvophyceae derive from different unicellular ancestors; therefore, the PD of these three classes likely originated independently (Raven 2005). The only other algae that have PD are the brown algae (Phaeophyceae) (Raven 2005) and all extant brown algae form multicellular bodies. Thus, including the Phaeophyceae, PD likely originated independently four times in photosynthetic organisms. However, we have little knowledge of the parallel evolution of PD. Recent studies in angiosperms have revealed several factors important for PD function (Burch-Smith and Zambryski 2012; De Storme and Geelen 2014; Overall et al. 2014), and the current, rapidly expanding availability of genome sequence information will allow us to identify candidate genes common for PD function in these organisms, which could provide many insights on PD evolution. This JPR symposium combines six review articles from different areas of PD studies, with four of the articles focusing on vascular plants, and two examining bryophytes and brown algae. All articles summarize recent advances and introduce current approaches to understand the biological functions and diversity of PD. In the first article, Kitagawa and Fujita (2015) provide an overview of how PD research in vascular plants, especially in A. thaliana, has uncovered the function and dynamic regulation of PD during plant development and in response to environmental changes. They also discuss how the model moss Physcomitrella patens can be exploited to understand PD function and evolution in land plants. PD