lants need nutrients to be able to grow. Unfortunately, many of these nutrients can be scarce in the soil and therefore hard to get hold of. To get around this problem, most plants are able to form friendly relationships – known as symbioses – with soil microbes that can provide them with certain nutrients in exchange for sugars.
Today, around 80% of land plants form symbioses with a group of fungi known as arbuscular mycorrhizal (AM) fungi (1). Fossil evidence suggests that this symbiosis first emerged around 450 million years ago. This is around the same time that plants first started to colonise land. The transition from water to the dry and harsh environments on land would have presented many challenges to the early land plants, for example, how to avoid losing too much water. Another challenge would have been how to access essential nutrients that their ancestor (a type of green algae) would have gained directly from the water.
Via Jean-Michel Ané