Best known for kissing under at Christmas-time, mistletoe (Viscum album) is a parasitic plant. It has been culturally important for centuries: in Roman mythology, the hero Aeneas used it to enter the underworld.
Living off others
Although mistletoe can gather energy by photosynthesis, it gets most of its nutrients and water by parasitism. It forms a specialised structure which invades the branch of a host tree, tapping into the vessels which transport water and sugar.
Mistletoe plants produce berries which are eaten by many birds. The seeds are coated in a very sticky substance called viscin which remains even after it has passed through the bird’s digestive system. If a seed lands on a tree branch it will stick tightly, then germinate into a new mistletoe plant, ready to invade a new host tree.
After germinating, mistletoe shoots force their way between the cells of a tree branch, stealing nutrients and water from the host.
A sticky problem
Viscin contains a network of cellulose and sugar molecules. Many other plants produce similar networks, but these are nowhere near as sticky or extensible as viscin. Yoshihisa has found that the structure of one of the sugars is different from those in other plants. He is currently investigating the structure of the other sugars in viscin and how they interact with cellulose, with the aim of understanding how viscin has such remarkable properties.
Yoshihisa Yoshimi (Department of Biochemistry)
About 80% of all carbon on earth is locked away as cellulose and sugar molecules in plant cell walls. Yoshihisa is excited by the potential to use cell walls for new materials. His research focuses on the composition of cell walls, aiming to explore the relationship between their architecture and function. This could also give us a better understanding of how plants grow and develop.