Arabidopsis SHORT HYPOCOTYL UNDER BLUE1 contains SPX and EXS domains and acts in cryptochrome signaling
Arabidopsis SHORT HYPOCOTYL UNDER BLUE1 contains SPX and EXS domains and acts in cryptochrome signaling
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DOI：
10.1105/tpc.105.037879
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发表时间：
2006-04-01
期刊：
影响因子：
11.6
通讯作者：
Ni, M
中科院分区：
文献类型：
--
作者：
Kang, XJ;Ni, M
光形态发生受红色/远红光吸收光敏色素和蓝色/UV-A 光吸收隐花色素的调节。我们分离出拟南芥蓝光突变体，即蓝色1（shb1）下的短下胚轴，这是一种敲除等位基因。然而，显性等位基因 shb1-D 在红光、远红光和蓝光下表现出长下胚轴表型。 shb1-D 赋予的表型是由 SHB1 转录物过度积累引起的，并通过拟南芥中 SHB1 的过度表达来概括。因此，SHB1 在隐花色素信号传导中发挥作用，但过度表达可能会将其信号传导活性扩展到红光和远红光。与此一致的是，SHB1 的过表达增强了红光下 PHYTOCHROME-INTERACTING FACTOR4 (PIF4) 的表达。 PIF4 似乎在红光下特异性介导 SHB1 对下胚轴伸长和叶绿素 a/b 结合蛋白 3 或查尔酮合成酶表达的调节。 SHB1的过度表达还促进了蛋白酶体介导的光敏色素A的降解和远红光下下胚轴的伸长。在蓝光下，shb1 抑制 LONG HYPOCOTYL IN FAR-RED LIGHT1 (HFR1) 的表达，并显示出几种与 hfr1-201 类似的脱黄化表型。然而，shb1的下胚轴和子叶开放表型与hfr1-201相反，并且HFR1作用于SHB1的下游。 SHB1 编码一种核蛋白和胞质蛋白，其基序与 SYG1 蛋白家族成员同源。因此，我们的研究揭示了调节隐花色素和可能的光敏色素介导的光反应的信号传导步骤。
Photomorphogenesis is regulated by red/far-red light-absorbing phytochromes and blue/UV-A light-absorbing cryptochromes. We isolated an Arabidopsis thaliana blue light mutant, short hypocotyl under blue1 (shb1), a knockout allele. However, shb1-D, a dominant allele, exhibited a long-hypocotyl phenotype under red, far-red, and blue light. The phenotype conferred by shb1-D was caused by overaccumulation of SHB1 transcript and recapitulated by overexpression of SHB1 in Arabidopsis. Therefore, SHB1 acts in cryptochrome signaling but overexpression may expand its signaling activity to red and far-red light. Consistent with this, overexpression of SHB1 enhanced the expression of PHYTOCHROME-INTERACTING FACTOR4 (PIF4) under red light. PIF4 appears to specifically mediate SHB1 regulation of hypocotyl elongation and CHLOROPHYLL a/b BINDING PROTEIN3 or CHALCONE SYNTHASE expression under red light. Overexpression of SHB1 also promoted proteasome-mediated degradation of phytochrome A and hypocotyl elongation under far-red light. Under blue light, shb1 suppressed LONG HYPOCOTYL IN FAR-RED LIGHT1 (HFR1) expression and showed several deetiolation phenotypes similar to hfr1-201. However, the hypocotyl and cotyledon-opening phenotypes of shb1 were opposite to those of hfr1-201, and HFR1 acts downstream of SHB1. SHB1 encodes a nuclear and cytosolic protein that has motifs homologous with SYG1 protein family members. Therefore, our studies reveal a signaling step in regulating cryptochrome- and possibly phytochrome-mediated light responses.