The Molecular Mechanism Of Zinc Finger Protein ZHE1 Involved In Photomorphogenesis Of Arabidopsis

Photoreceptors mediate the perception of light signals in the environment by plants and interact with signal proteins to transmit light signals in cells,thereby regulating the photomorphogensis of plants.Photomorphogenesis is an important physiological development process for light-dependent cell differentiation and organ formation of plants.However,the molecular mechanism of photomorphogenesis is not completely clear.By large-scale phenotypic screen,a C3 H zinc finger protein gene with unknown function was isolated from a transgenic plant population in which ?2,000 transcription factors are individually expressed and named as ZHE1(Zinc finger-controlled Hypocotyl Elongation1).Overexpression of ZHE1 enervated light sensitivity which leads to over-elongated hypocotyl,on the contrary,zhe1 mutants showed a reduced hypocotyl length,suggesting that ZHE1 is a light signaling protein that plays an important role in Arabidopsis photomorphogenesis.Therefore,this paper carried out related research on ZHE1 protein,and the results shows that:(1)under different light conditions,both ZHE1 transgenic lines and zhe1 mutants have different phenotypes in hypocotyl length from that of the wild type,and the different hypocotyl phenotypes only appeared under short day rather than long day condition.This suggests that ZHE1 involved in the regulation of Arabidopsis photomorphogenesis and plays a role as an inhibitor in the light signaling pathway.(2)ZHE1 transgenic lines showed obvious developmental phenotypes such as premature leaf senescence and early flowering under long day condition,indicating that ZHE1 could also play an important role in the growth and development of Arabidopsis.(3)ZHE1 is a cytoplasmic zinc finger protein,and no matter the transcriptional level or protein abundance of ZHE1 is not regulated by light,suggesting that ZHE1 is a stable protein in dark or light,and its regulating mechanism in hypocotyl growth may be accomplished by protein-protein interaction.(4)ZHE1 interacting proteins were identified by immunoprecipitation-mass spectrometry analysis in Arabidopsis.These interacting proteins included:red/far red light receptor phy A,blue light receptors CRY1 and CRY2,a regulator of phy A karyopherin-FHY3,FRS7 and FRS12 that form a large number of heterodimers under short day condition.We also verified these interactions in the HEK293 T system.The results are similar.All these results indicate that ZHE1 may play important roles in multiple light signaling pathways.Furthermore,the hypocotyl phenotypes of ZHE1 transgenic lines and zhe1 mutants under different lights and short day condition may also be related to these interacting proteins.(5)ZHE1 was verified to interact with the Pr(inactive)form of phy A by HEK293 T system.It was observed by laser confocal microscopy that in the dark ZHE1 could co-localize in the cytoplasm with the Pr form of phy A.After exposure to the light,a part of phy A proteins in ZHE1 transgenic plants were retained in the cytoplasm rather than entering into the nucleus,leading to the slow degradation of phy A and finally regulating the photomorphogenesis in red/far red light.In summary,ZHE1 can participate in the regulation of hypocotyl growth in the light signaling pathways under red/far-red light,blue light and short day condition.Moreover,the special developmental phenotype of ZHE1 transgenic lines under long day condition also indicated that ZHE1 could regulate various growth and development processes of Arabidopsis.These results provide a theoretical basis for further study on the functional diversity of ZHE1 in light signal transduction and the mechanism of ZHE1 in regulating various growth and development signals in Arabidopsis.