Glc- and simulated shade-mediated transcriptional regulation of RSS1 in Arabidopsis. (a) Relative expression of RSS1 on different sugar treatment shows that RSS1 is specifically repressed by Glc and sucrose (Suc), seedlings treated with sugar free ½ MS media were considered as control. (b) The HXK1-dependent Glc signaling mutant gin2-1 showed relatively higher RSS1 transcript accumulation as compared with WT. (c) Analysis of Glc mediated repression of RSS1 transcript levels in HXK1-dependent and HXK1-independent Glc signaling mutants suggested involvement of HXK1-dependent signaling pathway in controlling RSS1 transcription. (d) Effect of EODFR mediated simulated shade conditions on RSS1 transcript abundance. 3-d-old WT (Col-0) seedlings growing under short day (SD) conditions were exposed to FR light at the end-of the light and RSS1 transcript levels were quantified after various time points. The RSS1 transcripts were significantly induced within 15 min reaching a maximum level at 1 h exposure to EODFR pulse suggesting RSS1 to be an early shade inducible gene. (e) The RSS1pro:GUS reporter expression was significantly induced upon 1 h EODFR exposure as compared with SD control. (f) Increasing Glc concentration could significantly repress RSS1pro:GUS reporter expression under control conditions whereas under shaded conditions, RSS1 expression was enhanced in presence of Glc. Expression values represent the average of two biological replicates with three technical replicates each and error bar represents SE. (Student’s t-test; P < 0.05; *control vs. treatment; **WT vs. mutant).