The sunflower HD-Zip transcription factor HAHB4 is up-regulated in darkness, reducing the transcription of photosynthesis-related genes
The sunflower HD-Zip transcription factor HAHB4 is up-regulated in darkness, reducing the transcription of photosynthesis-related genes
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DOI：
10.1093/jxb/ern170
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发表时间：
2008-08-01
影响因子：
6.9
通讯作者：
Chan, Raquel L.
中科院分区：
文献类型：
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作者：
Manavella, Pablo A.;Dezar, Carlos A.;Chan, Raquel L.
HAHB 4属于HD-Zip蛋白的向日葵亚家族I，并且参与耐旱性反应和乙烯介导的衰老。最近描述了通过该转录因子的这两个过程之间的串扰。在这项研究中，它表明，HAHB 4的表达诱导在黑暗中，并迅速消失，当植物暴露于光。通过使用带有构建体的转基因拟南芥植物在转录水平上证实了HAHB 4的这种调节，其中HAHB 4启动子的不同片段与报告基因GUS融合。连同电泳迁移率变动与向日葵核蛋白进行测定，这些实验允许参与这种反应的顺式作用元件被定位。瞬时过表达的HAHB 4 cDNA在向日葵叶盘和HAHB 4敲低的iRNA进行，证明了这种转录因子的参与，在转录下调的一大组光合作用相关基因。与编码叶绿素a/b结合蛋白的转录物的减少一致，这些色素的含量在拟南芥HAHB 4表达转基因植物中减少。因此，似乎HAHB 4可能与其他因子一起参与黑暗中光合机制的复杂调节机制。
HAHB4 belongs to the sunflower subfamily I of HD-Zip proteins and is involved in drought-tolerance response and ethylene-mediated senescence. Cross-talk between these two processes through this transcription factor was recently described. In this study it is shown that the expression of HAHB4 is induced in darkness and quickly disappears when plants are exposed to light. This regulation of HAHB4 was confirmed at the transcriptional level through the use of transgenic Arabidopsis plants bearing constructs in which different segments of the HAHB4 promoter were fused with the reporter gene GUS. Together with electrophoretic mobility shift assays performed with sunflower nuclear proteins, these experiments allowed a cis-acting element involved in this response to be located. Transient overexpression of the HAHB4 cDNA in sunflower leaf discs and HAHB4 knockdown by iRNA were performed, demonstrating the participation of this transcription factor in the transcriptional down-regulation of a large group of photosynthesis-related genes. In accordance with the reduction in the transcripts encoding chlorophyll a/b-binding proteins, the content of these pigments is diminished in Arabidopsis HAHB4-expressing transgenic plants. Thus, it appears that HAHB4 may participate with other factors in the intricate regulation mechanism of the photosynthetic machinery in darkness.