Plants have a love-hate relationship with sunlight. While some wavelengths are indispensable to them for performing photosynthesis, others, such as UV-B, are deleterious. Therefore, plants are equipped to detect these highly toxic rays and mount their defences. A team led by Roman Ulm, Professor at the Faculty of Sciences at the University of Geneva (UNIGE), Switzerland, has generated a transgenic plant which acclimatises constitutively, regardless of the level of UV-B. This plant possesses a constantly active receptor, which endows it with a higher UV resistance, associated with increased flavonoid production, substances which function as a 'sunscreen' and as antioxidants. Flavonoid-rich plants also provide a powerful source of antioxidants for humans. As described in the journal PNAS, this transgenic plant is an excellent model system within the framework of basic research, as well as studies aiming at improving crop plants.
Plants have an arsenal of receptors that enable them to benefit from all components of solar radiation. While the energy of some photons is captured by chlorophyll to produce sugar, other wavelengths regulate essential processes, such as flowering, seed germination, shade avoidance and phototropism. 'Even ultraviolet B rays, despite their harmfulness, are used by plants as an environmental stimulus and influence plant growth and development', points out Roman Ulm, Professor at the UNIGE Department of Botany and Plant Biology.
A maximal survival response
Ultraviolet B rays (UV-B), which account for 0.5% of light energy, are dangerous for living organisms as they lead to the formation of free radicals in cells and damage their DNA. Unable to escape them, plants are forced to find a way to protect themselves. They detect UV-B rays thanks to a receptor knows as UVR8, thus triggering a biochemical chain reaction within the cells and allowing them to mount their defences. These are notably made up of flavonoids, which
|Contact: Roman Ulm|
Universit de Genve