Cross-talk between ethylene and drought signalling pathways is mediated by the sunflower Hahb-4 transcription factor
Cross-talk between ethylene and drought signalling pathways is mediated by the sunflower Hahb-4 transcription factor
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DOI：
10.1111/j.1365-313x.2006.02865.x
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发表时间：
2006-10-01
期刊：
影响因子：
7.2
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.;Arce, Agustin L.;Chan, Raquel L.
Hahb-4是向日葵（向日葵）HD-Zip蛋白亚家族I的成员，其转录受水分利用率和脱落酸调节。过表达该转录因子（TF）的转基因拟南芥植物表现出包括对水分胁迫的强耐受性的特征表型。在这里，我们表明，这种TF是乙烯信号通路的一个新的组成部分，它诱导衰老的显着延迟。过表达Hahb-4的植物对外部乙烯的敏感性较低，进入衰老途径较晚，不显示典型的三重响应。此外，在其自身的诱导型启动子的控制下表达该基因的转基因植物表现出乙烯敏感性和Hahb-4水平之间的负相关。通过使用微阵列和定量RT-PCR比较Hahb-4转化的和野生型植物的转录组来鉴定Hahb-4的潜在靶标。该TF的表达对与乙烯合成相关的基因（如ACO和SAM）和与乙烯信号传导相关的基因（如ERF 2和ERF 5）具有主要的抑制作用。向日葵中的表达研究表明，Hahb-4转录水平在成熟/衰老叶中升高。Hahb-4的表达由乙烯诱导，伴随着与转录组分析中鉴定的靶同源的几个基因（HA-ACOa和HA-ACOb）。向日葵叶片的瞬时转化证明了Hahb- 4在乙烯相关基因的调节中的作用。我们建议，Hahb- 4参与了一个新的保守机制，乙烯介导的衰老，功能，以提高脱水耐受性。
Hahb-4 is a member of the Helianthus annuus ( sunflower) subfamily I of HD-Zip proteins that is transcriptionally regulated by water availability and abscisic acid. Transgenic Arabidopsis thaliana plants over expressing this transcription factor ( TF) exhibit a characteristic phenotype that includes a strong tolerance to water stress. Here we show that this TF is a new component of ethylene signalling pathways, and that it induces a marked delay in senescence. Plants overexpressing Hahb-4 are less sensitive to external ethylene, enter the senescence pathway later and do not show the typical triple response. Furthermore, transgenic plants expressing this gene under the control of its own inducible promoter showed an inverse correlation between ethylene sensitivity and Hahb-4 levels. Potential targets of Hahb-4 were identified by comparing the transcriptome of Hahb-4-transformed and wild-type plants using microarrays and quantitative RT-PCR. Expression of this TF has a major repressive effect on genes related to ethylene synthesis, such as ACO and SAM, and on genes related to ethylene signalling, such as ERF2 and ERF5. Expression studies in sunflower indicate that Hahb-4 transcript levels are elevated in mature/senescent leaves. Expression of Hahb-4 is induced by ethylene, concomitantly with several genes homologous to the targets identified in the transcriptome analysis ( HA-ACOa and HA-ACOb). Transient transformation of sunflower leaves demonstrated the action of Hahb- 4 in the regulation of ethylene-related genes. We propose that Hahb- 4 is involved in a novel conserved mechanism related to ethylene-mediated senescence that functions to improve desiccation tolerance.