Hypocotyl development in Arabidopsis thaliana is regulated by light and endogenous hormonal cues, mak- ing it an ideal model to study the interplay between light and endogenous growth regulators. BBX21, a B-box （BBX...Hypocotyl development in Arabidopsis thaliana is regulated by light and endogenous hormonal cues, mak- ing it an ideal model to study the interplay between light and endogenous growth regulators. BBX21, a B-box （BBX）-Iike zinc-finger transcription factor, integrates light and abscisic acid signals to regulate hypocotyl elongation in Arabidopsis. Heterotrimeric G-proteins are pivotal regulators of plant development. The short hypocotyl phenotype of the G-protein I^-subunit （AGB1） mutant （agbl-2） has been previously identified, but the precise role of AGB1 in hypocotyl elongation remains enigmatic. Here, we show that AGB1 directly interacts with BBX21, and the short hypocotyl phenotype of agbl-2 is partially suppressed in agb1-2bbx21-1 double mutant. BBX21 functions in the downstream of AGB1 and overexpression of BBX21 in agbl-2 causes a more pronounced reduction in hypocotyl length, indicating that AGB1 plays an oppositional role in relation to BBX21 during hypocotyl development. Furthermore, we demonstrate that the C-terminal region of BBX21 is important for both its intracellular localization and its transcriptional activation activity that is inhibited by interaction with AGB1. ChiP assays showed that BBX21 specifically associates with its own promoter and with those of BBX22, HY5, and GA2oxl. which is not altered in agbl-2. These data suggest that the AGB1-BBX21 interaction only affects the transcrip- tional activation activity of BBX21 but has no effect on its DNA binding ability. Taken together, our data demonstrate that AGB1 positively promotes hypocotyl elongation through repressing BBX21 activity.展开更多
Light is one of the most essential environmental factors that tightly and precisely control various physiological and developmental processes in plants.B-box CONTAINING PROTEINs(BBXs)play central roles in the regulati...Light is one of the most essential environmental factors that tightly and precisely control various physiological and developmental processes in plants.B-box CONTAINING PROTEINs(BBXs)play central roles in the regulation of light-dependent development.In this study,we report that BBX9 is a positive regulator of light signaling.BBX9 interacts with the red light photoreceptor PHYTOCHROME B(phyB)and transcription factors PHYTOCHROME-INTERACTING FACTORs(PIFs).phyB promotes the stabilization of BBX9 in light,while BBX9 inhibits the transcriptional activation activity of PIFs.In turn,PIFs directly bind to the promoter of BBX9 to repress its transcription.On the other hand,BBX9 associates with the positive regulator of light signaling,BBX21,and enhances its biochemical activity.BBX21 associates with the promoter regions of BBX9 and transcriptionally up-regulates its expression.Collectively,this study unveiled that BBX9 forms a negative feedback loop with PIFs and a positive one with BBX21 to ensure that plants adapt to fluctuating light conditions.展开更多
文摘Hypocotyl development in Arabidopsis thaliana is regulated by light and endogenous hormonal cues, mak- ing it an ideal model to study the interplay between light and endogenous growth regulators. BBX21, a B-box （BBX）-Iike zinc-finger transcription factor, integrates light and abscisic acid signals to regulate hypocotyl elongation in Arabidopsis. Heterotrimeric G-proteins are pivotal regulators of plant development. The short hypocotyl phenotype of the G-protein I^-subunit （AGB1） mutant （agbl-2） has been previously identified, but the precise role of AGB1 in hypocotyl elongation remains enigmatic. Here, we show that AGB1 directly interacts with BBX21, and the short hypocotyl phenotype of agbl-2 is partially suppressed in agb1-2bbx21-1 double mutant. BBX21 functions in the downstream of AGB1 and overexpression of BBX21 in agbl-2 causes a more pronounced reduction in hypocotyl length, indicating that AGB1 plays an oppositional role in relation to BBX21 during hypocotyl development. Furthermore, we demonstrate that the C-terminal region of BBX21 is important for both its intracellular localization and its transcriptional activation activity that is inhibited by interaction with AGB1. ChiP assays showed that BBX21 specifically associates with its own promoter and with those of BBX22, HY5, and GA2oxl. which is not altered in agbl-2. These data suggest that the AGB1-BBX21 interaction only affects the transcrip- tional activation activity of BBX21 but has no effect on its DNA binding ability. Taken together, our data demonstrate that AGB1 positively promotes hypocotyl elongation through repressing BBX21 activity.
基金supported by the Natural Science Foundation of Jiangsu for Distinguished Young Scholars(BK20211525)the Fundamental Research Funds for the Central Universities(YDZX2024045)+3 种基金the National Natural Science Foundation of China(32270256)the Postdoctoral Fellowship Program of CPSF(GZB20240319)the Core Technology Development for Breeding Program of Jiangsu Province(JBGS‐2021‐014)the Jiangsu Collaborative Innovation Center for Modern Crop Production(to D.X.)。
文摘Light is one of the most essential environmental factors that tightly and precisely control various physiological and developmental processes in plants.B-box CONTAINING PROTEINs(BBXs)play central roles in the regulation of light-dependent development.In this study,we report that BBX9 is a positive regulator of light signaling.BBX9 interacts with the red light photoreceptor PHYTOCHROME B(phyB)and transcription factors PHYTOCHROME-INTERACTING FACTORs(PIFs).phyB promotes the stabilization of BBX9 in light,while BBX9 inhibits the transcriptional activation activity of PIFs.In turn,PIFs directly bind to the promoter of BBX9 to repress its transcription.On the other hand,BBX9 associates with the positive regulator of light signaling,BBX21,and enhances its biochemical activity.BBX21 associates with the promoter regions of BBX9 and transcriptionally up-regulates its expression.Collectively,this study unveiled that BBX9 forms a negative feedback loop with PIFs and a positive one with BBX21 to ensure that plants adapt to fluctuating light conditions.
