Molecular Mechanism Of Adult Plant Growth Regulated By UV-B Light In Arabidopsis

Light is one of the most critical environmental factors for plant development.UV-B light(280-315 nm)is an intrinsic part of the sunlight.UV RESISTANCE LOCUS 8(UVR8)is the UV-B photoreceptor in Arabidopsis.Long-wavelength and low-fluence UV-B regulates plant growth and develop ment such as the inhibition of hypocotyl elongation and the induction of flavonoid accumulation,and the regulation of UV-B to plant development has been linked to UVR8 photoreceptor activity.UVR8-mediated UV-B signaling is very important for plant,but the mechanism of UVR8-mediated UV-B signaling is not particularly clear.A previous study of UV-B photoreceptor UVR8 in our lab indicated that the component of Evening Complex(EC),ELF4 might interact with UVR8.EC is an essential component of the evening transcription loop,consisting of EARLY FLOWERING3,4(ELF3 and 4)and LUX ARRYTHMO(LUX).We performed luciferase complementary imaging assay and in vitro pull-down assay and found that the components of EC physically interacted with UVR8.At the adult stage of Arabidopsis,the components of EC acted as positive regulators in UV-B-inhibited petiole elongation and flowering.We also found that UV-B inhibited the expression of genes which were involved in regulating petiole elongation and flowering and it depend on UVR8 and the components of EC.However,we observed that ELF3 and LUX were not involved in UV-B-induced photomorphogenesis and ELF4 acted as a negative regulator at the seedling stage.Taken together,this study reveals that the components of EC are involved in UV-B and UVR8-mediated plant development by regulating the transcription of genes involved in regulating petiole elongation and flowering at the adult stage.