Charophytes: Evolutionary ancestors of plants and emerging models for plant research

The charophytes (Streptophyta,Virideplantae) are the extant group of green algae that are most closely related to modern land plants. Approximately 450-500 million years ago, an ancestral charophyte emerged onto land and ultimately gave rise to terrestrial plants, an event of profound significance in the natural history of the planet. Recent molecular, biochemical and cell biology-based studies have demonstrated that some extant charophytes have remarkable similarities to land plants, notably in cell wall chemistry, many metabolic pathways and hormone signaling systems. Coupled with simple thallus construction and ease in experimental manipulation, charophytes are becoming efficacious model organisms in the elucidation of many basic aspects of plant life. Taxa such as Penium, Chara, Coleochaete, Spirogyra and Micrasterias are yielding key insight into such fundamental processes as cell wall dynamics and polar cell growth, cytoplasmic streaming, gravitropism, cell division and morphogenesis. Recent advances in accessing transcriptomic and genomic data of charophytes along with application of forward/reverse genetics and transformation technology to various studies are adding detailed insight into charophyte biology, evolution and plant biology in general. The widespread distribution of charophytes in many of the planet’s habitats has also made them important taxa for understanding ecosystem dynamics and stress perception and response. This is exemplified in taxa such as Klebsormidium in desert soil dynamics and various desmids living in high UV-stress habitats. This Research Topic reviews the current status of charophyte phylogeny and welcomes articles about emerging genomic data and the role of these algae in various areas research.