The transcriptional repressor ARR1-SRDX suppresses pleiotropic cytokinin activities in Arabidopsis
The transcriptional repressor ARR1-SRDX suppresses pleiotropic cytokinin activities in Arabidopsis
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DOI：
10.1104/pp.107.115436
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发表时间：
2008-07-01
期刊：
影响因子：
7.4
通讯作者：
Schmuelling, Thomas
中科院分区：
文献类型：
--
作者：
Heyl, Alexander;Ramireddy, Eswar;Schmuelling, Thomas
植物激素细胞分裂素的信号转导是由一个多步骤的组氨酸-天冬氨酸磷酸化系统介导的。该系统的一个组成部分是B型反应调节因子，转录因子介导至少部分对细胞分裂素的反应。在植物功能分析这个家庭是阻碍了高水平的功能冗余的11个成员。为了研究B型反应调节因子对细胞分裂素活性的贡献程度，我们利用嵌合阻遏物沉默技术构建了拟南芥反应调节因子ARR 1（ARR 1-SRDX）的显性阻遏物。在原生质体测试系统中，ARR 1- SRDX抑制不同B型ARR对ARR 6：β-葡萄糖醛酸酶报告基因的激活。35S：ARR 1- SRDX转基因拟南芥植物表现出的表型变化，让人联想到植物细胞分裂素的状态，如强烈减少叶片大小，增强根系，和更大的种子。一些生物测定表明，35 S：ARR 1- SRDX植物对细胞分裂素的抗性增加。大部分细胞分裂素反应基因的快速诱导受到抑制。在35 S：ARR 1- SRDX转基因幼苗中，超过500个基因的转录水平降低了2.5倍以上，表明B型ARR具有广泛的功能。总的来说，由B型ARR的显性阻遏物版本对多效性细胞分裂素活性的抑制表明，该蛋白质家族参与介导拟南芥中的大多数（如果不是全部）细胞分裂素活性。此外，35 S：ARR 1- SRDX种子对光敏色素B介导的远红光萌发抑制的抗性支持了B型ARR在介导与其他途径的串扰中的作用。这项研究证明了嵌合阻遏物沉默技术的有用性，以克服冗余的转录因子家族的功能研究。
The signal transduction of the phytohormone cytokinin is mediated by a multistep histidine- to-aspartate phosphorelay system. One component of this system are B-type response regulators, transcription factors mediating at least part of the response to cytokinin. In planta functional analysis of this family is hampered by the high level of functional redundancy of its 11 members. We generated a dominant repressor version of the Arabidopsis ( Arabidopsis thaliana) response regulator ARR1 ( ARR1-SRDX) using chimeric repressor silencing technology in order to study the extent of the contribution of B-type response regulators to cytokinin activities. In a protoplast test system, ARR1- SRDX suppressed ARR6: beta- glucuronidase reporter gene activation by different B-type ARRs. 35S: ARR1- SRDX transgenic Arabidopsis plants showed phenotypic changes reminiscent of plants with a reduced cytokinin status, such as a strongly reduced leaf size, an enhanced root system, and larger seeds. Several bioassays showed that 35S: ARR1- SRDX plants have an increased resistance toward cytokinin. The rapid induction of a large part of the cytokinin response genes was dampened. The transcript levels of more than 500 genes were more than 2.5- fold reduced in 35S: ARR1- SRDX transgenic seedlings, suggesting a broad function of B-type ARRs. Collectively, the suppression of pleiotropic cytokinin activities by a dominant repressor version of a B-type ARR indicates that this protein family is involved in mediating most, if not all, of the cytokinin activities in Arabidopsis. In addition, a role for B-type ARRs in mediating cross talk with other pathways is supported by the resistance of 35S: ARR1- SRDX seeds to phytochrome B-mediated inhibition of germination by far-red light. This study demonstrates the usefulness of chimeric repressor silencing technology to overcome redundancy in transcription factor families for functional studies.