SOMNUS, a CCCH-type zinc finger protein in Arabidopsis, negatively regulates light-dependent seed germination downstream of PIL5
SOMNUS, a CCCH-type zinc finger protein in Arabidopsis, negatively regulates light-dependent seed germination downstream of PIL5
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DOI：
10.1105/tpc.108.058859
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发表时间：
2008-05-01
期刊：
影响因子：
11.6
通讯作者：
Choi, Giltsu
中科院分区：
文献类型：
--
作者：
Kim, Dong Hwan;Yamaguchi, Shinjiro;Choi, Giltsu
拟南芥种子光敏色素吸收的光至少部分地通过光敏色素相互作用因子3样5（PIL 5）调节脱落酸（阿坝）和赤霉酸（GA）信号通路。在这里，我们报告了一个新的突变体，somnus（som），在黑暗中发芽，独立于各种光照方案。SOM编码一种核定位的CCCH型锌指蛋白。由于阿坝和GA代谢基因的表达变化，som突变体具有较低的阿坝水平和升高的GA水平。然而，与PIL 5不同的是，SOM不调节GA不敏感和GA 1的恢复（RGA/RGA 1）的表达，这两个DELLA基因编码GA负信号组分。我们的体内分析表明，PIL 5激活SOM的表达，直接结合到其启动子，表明PIL 5调节阿坝和GA代谢基因部分通过SOM。与这些结果一致，我们还观察到PIL 5过表达系的降低的发芽频率被som突变拯救，并且这种拯救伴随着阿坝和GA代谢基因的表达变化。综上所述，我们的研究结果表明，SOM是植物光敏色素信号转导途径中的一个组成部分，在种子萌发过程中调节PIL 5下游的激素代谢基因。
Light absorbed by seed phytochromes of Arabidopsis thaliana modulates abscisic acid (ABA) and gibberellic acid (GA) signaling pathways at least partly via PHYTOCHROME-INTERACTING FACTOR3-LIKE5 (PIL5), a phytochrome-interacting basic helix-loop-helix transcription factor. Here, we report a new mutant, somnus (som), that germinates in darkness, independently of various light regimens. SOM encodes a nucleus-localized CCCH-type zinc finger protein. The som mutant has lower levels of ABA and elevated levels of GA due to expressional changes in ABA and GA metabolic genes. Unlike PIL5, however, SOM does not regulate the expression of GA-INSENSITIVE and REPRESSOR OF GA1 (RGA/RGA1), two DELLA genes encoding GA negative signaling components. Our in vivo analysis shows that PIL5 activates the expression of SOM by binding directly to its promoter, suggesting that PIL5 regulates ABA and GA metabolic genes partly through SOM. In agreement with these results, we also observed that the reduced germination frequency of a PIL5 overexpression line is rescued by the som mutation and that this rescue is accompanied by expressional changes in ABA and GA metabolic genes. Taken together, our results indicate that SOM is a component in the phytochrome signal transduction pathway that regulates hormone metabolic genes downstream of PIL5 during seed germination.