Liverworts and fungi: one of the earliest mutualistic relationships

What is it about?

Liverworts are a unique and ancient plant division, loosely related to moss. Like moss liverworts grow close to the ground with ill-defined leaves and stems, and – like higher plants – they can form a symbiotic relationship with fungi. This symbiosis is thought to have been crucial for plants' colonization of land. Until recently, liverworts were believed to associate exclusively with the glomeromycota group of fungi. However, new molecular data have emerged showing that another set of fungi – mucoromycotina – associate with the earliest diverging group of liverworts. Investigating the evolution of symbioses This study sought to understand more about mucoromycotina symbiosis. Specifically, it compared the symbiosis with the better-known glomeromycota symbiosis. Approximately 400 million years ago, there was a sharp decline in the amount of carbon dioxide in the atmosphere. Therefore, the researchers investigated how the different symbioses react to carbon dioxide concentration change. Unexpected similarities The results showed that there were similarities between mucoromycotina- and glomeromycota-liverwort symbioses; both symbioses were mutually beneficial. This means that the fungi provide around as much phosphorus and nitrogen to the liverwort as the liverwort provides carbohydrates to the fungi. There were striking differences between how the two symbioses reacted to changes in carbon dioxide. The glomeromycota were far less efficient if the carbon dioxide supply was reduced than the mucoromycotina. The findings in this study strengthen the view that mucoromycotina fungi were vital to the evolution of early land plants.

Featured Image