Harris John C, Sornaraj Pradeep, Taylor Mathew, Bazanova Natalia, Baumann Ute, Lovell Ben, Langridge Peter, Lopato Sergiy, Hrmova Maria
From the Australian Centre for Plant Functional Genomics, School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, SA, 5064, Australia.
South Australian Research and Development Institute, Waite Campus, Glen Osmond, SA, 5064, Australia.
Plant Mol Biol. 2016 Mar;90(4-5):435-52. doi: 10.1007/s11103-015-0427-6. Epub 2016 Jan 23.
The γ-clade of class I homeodomain-leucine zipper (HD-Zip I) transcription factors (TFs) constitute members which play a role in adapting plant growth to conditions of water deficit. Given the importance of wheat (Triticum aestivum L.) as a global food crop and the impact of water deficit upon grain yield, we focused on functional aspects of wheat drought responsive HD-Zip I TFs. While the wheat γ-clade HD-Zip I TFs share significant sequence similarities with homologous genes from other plants, the clade-specific features in transcriptional response to abiotic stress were detected. We demonstrate that wheat TaHDZipI-3, TaHDZipI-4, and TaHDZipI-5 genes respond differentially to a variety of abiotic stresses, and that proteins encoded by these genes exhibit pronounced differences in oligomerisation, strength of DNA binding, and trans-activation of an artificial promoter. Three-dimensional molecular modelling of the protein-DNA interface was conducted to address the ambiguity at the central nucleotide in the pseudo-palindromic cis-element CAATNATTG that is recognised by all three HD-Zip I proteins. The co-expression of these genes in the same plant tissues together with the ability of HD-Zip I TFs of the γ-clade to hetero-dimerise suggests a role in the regulatory mechanisms of HD-Zip I dependent transcription. Our findings highlight the complexity of TF networks involved in plant responses to water deficit. A better understanding of the molecular complexity at the protein level during crop responses to drought will enable adoption of efficient strategies for production of cereal plants with enhanced drought tolerance.
I 类同源异型域 - 亮氨酸拉链（HD - Zip I）转录因子（TFs）的γ分支成员在使植物生长适应水分亏缺条件方面发挥作用。鉴于小麦（Triticum aestivum L.）作为全球粮食作物的重要性以及水分亏缺对谷物产量的影响，我们聚焦于小麦干旱响应HD - Zip I转录因子的功能方面。虽然小麦γ分支HD - Zip I转录因子与其他植物的同源基因具有显著的序列相似性，但检测到了其在对非生物胁迫的转录响应中的分支特异性特征。我们证明，小麦TaHDZipI - 3、TaHDZipI - 4和TaHDZipI - 5基因对多种非生物胁迫有不同的响应，并且这些基因编码的蛋白质在寡聚化、DNA结合强度以及人工启动子的反式激活方面表现出明显差异。对蛋白质 - DNA界面进行了三维分子建模，以解决由所有三种HD - Zip I蛋白质识别的假回文顺式元件CAATNATTG中中央核苷酸的模糊性问题。这些基因在同一植物组织中的共表达以及γ分支HD - Zip I转录因子异源二聚化的能力表明其在HD - Zip I依赖性转录的调控机制中发挥作用。我们的研究结果突出了植物对水分亏缺响应中涉及的转录因子网络的复杂性。更好地理解作物对干旱响应过程中蛋白质水平的分子复杂性将有助于采用有效的策略来培育耐旱性增强的谷类植物。
