In the past, Ultraviolet B (UV-B) was mainly documented as a stress factor, yet now it is wellknown
that UV-B light affects plant morphology and metabolism through a specific UV-B
photoreceptor pathway (UVR8). In the model dicot plant Arabidopsis, UV-B inhibition of
elongation and cell expansion yields small, compact plants. A large portion of this response is
mediated by UVR8. Although, a role for the plant hormone auxin has been documented
extensively, gibberellins (GA) and brassinosteroids (BR) have been respectively far less or totally
not been studied in this context.
The main objective of this project is to identify crucial downstream components of the UV-B
induced pathway that lead to growth inhibition and to interpret the larger context of mechanisms
that steer UV-B controlled growth. We will attempt to understand the possible role of growth
regulatory bHLH factors in the photomorphogenic UV-B response. Many growth promoting bHLH
factors are under the control of the elongation stimulating hormones BR and GA. At this moment it
is unknown whether and how UV-B impacts on BR and/or GA controlled growth or on growth
regulating bHLH genes. We therefore propose to perform research on a potential physiological link
between UV-B growth regulation and the BR/GA metabolism, signalling and responses.