Kim Young-Mi, Woo Je-Chang, Song Pill-Soon, Soh Moon-Soo
Kumho Life & Environmental Science Laboratory, 1 Oryong-Dong, Buk-Gu, Gwangju 500-712, Republic of Korea.
Plant J. 2002 Jun;30(6):711-9. doi: 10.1046/j.1365-313x.2002.01326.x.
HFR1, a basic helix-loop-helix protein, is known to be required for a subset of phytochrome A (phyA)-dependent photoresponses. To investigate the role of HFR1 in light signalling, we have examined the genetic interaction between HFR1 and HY5, a positive regulator of light signalling, and COP1, a repressor of photomorphogenesis. Double mutant analysis suggests that HFR1 mediates phyA-dependent inhibition of hypocotyl elongation independently of HY5. HFR1 was shown to be necessary for a subset of cop1-triggered photomorphogenic phenotypes in the dark, including inhibition of hypocotyl elongation, gravitropic hypocotyl growth, and expression of the light-inducible genes CAB and RBCS. Phenotypic analysis of the triple mutant cop1hy5hfr1 indicated that both HFR1 and HY5 are required for cop1-mediated photomorphogenic seedling development in darkness, consistent with their additive roles in phyA-dependent signalling. Taken together, these results suggest that HFR1 might act downstream of COP1, in a separate pathway from HY5, to mediate photomorphogenesis in Arabidopsis.
HFR1是一种碱性螺旋-环-螺旋蛋白，已知它是一部分依赖于光敏色素A（phyA）的光反应所必需的。为了研究HFR1在光信号传导中的作用，我们检测了HFR1与光信号的正向调节因子HY5以及光形态建成的抑制因子COP1之间的遗传相互作用。双突变体分析表明，HFR1独立于HY5介导phyA依赖的下胚轴伸长抑制。研究表明，HFR1对于黑暗中cop1触发的一部分光形态建成表型是必需的，包括下胚轴伸长的抑制、下胚轴的向重力性生长以及光诱导基因CAB和RBCS的表达。三重突变体cop1hy5hfr1的表型分析表明，HFR1和HY5都是黑暗中cop1介导的光形态建成幼苗发育所必需的，这与其在依赖于phyA的信号传导中的累加作用一致。综上所述，这些结果表明，HFR1可能在COP1的下游起作用，通过一条独立于HY5的途径介导拟南芥中的光形态建成。
