The wheat TabZIP2 transcription factor is activated by the nutrient starvation-responsive SnRK3/CIPK protein kinase
The understanding of roles of bZIP factors in biological processes during plant development and under abiotic stresses requires the detailed mechanistic knowledge of behaviour of TFs.
Basic leucine zipper (bZIP) transcription factors (TFs) play key roles in the regulation of grain development and plant responses to abiotic stresses. We investigated the role and molecular mechanisms of function of the TabZIP2 gene isolated from drought-stressed wheat plants. Molecular characterisation of TabZIP2 and derived protein included analyses of gene expression and its target promoter, and the influence of interacting partners on the target promoter activation. Two interacting partners of TabZIP2, the 14-3-3 protein, TaWIN1 and the bZIP transcription factor TaABI5L, were identified in a Y2H screen. We established that under elevated ABA levels the activity of TabZIP2 was negatively regulated by the TaWIN1 protein and positively regulated by the SnRK3/CIPK protein kinase WPK4, reported previously to be responsive to nutrient starvation. The physical interaction between the TaWIN1 and the WPK4 was detected. We also compared the influence of homo- and hetero-dimerisation of TabZIP2 and TaABI5L on DNA binding. TabZIP2 gene functional analyses were performed using drought-inducible overexpression of TabZIP2 in transgenic wheat. Transgenic plants grown under moderate drought during flowering, were smaller than control plants, and had fewer spikes and seeds per plant. However, a single seed weight was increased compared to single seed weights of control plants in three of four evaluated transgenic lines. The observed phenotypes of transgenic plants and the regulation of TabZIP2 activity by nutrient starvation-responsive WPK4, suggest that the TabZIP2 could be the part of a signalling pathway, which controls the rearrangement of carbohydrate and nutrient flows in plant organs in response to drought.
Keywords14-3-3 protein 3D protein molecular modelling Drought Homo- and hetero-dimerisation SnRK3/CIPK protein kinase Wheat
Discrete optimised protein energy
Green fluorescent protein
- HD-Zip I
Homeodomain-leucine zipper class I
International Wheat Genome Sequencing Consortium
Late embryogenesis abundant
Modeller objective function
The plant transformation contribution of Ainur Ismagul is acknowledged. We also thank Ursula Langridge, Larissa Chirkova and Yagnesh Nagarajan for technical assistance, and Julie Hayes and Carl Simmons for critically reading the manuscript. Pradeep K. Agarwal is grateful to the Council of Scientific and Industrial Research of India (Raman Research Fellowship) and Syed Sarfraz Hussain to DuPont Pioneer for funding their fellowships. This work was supported by the Australian Research Council (LP120100201 to MH and SL), the Australian Grains Research and Development Corporation, the Government of South Australia, and DuPont Pioneer, as part of LP120100201.
Conceived, designed experiments and analysed data: SLu, PS, MH and SLo. Plant growth and transformation: PS, NK, OE and PKA. Cloning, Y1H, pull-down and transient expression assays, Q-PCR experiments: WJ, NBa and SLo. Protein–protein interactions: SH and MH. 3D molecular modelling: SLu and MH. Discussed the data and contributed to writing: SLu and PS. Writing of the manuscript: SLo and MH.
Compliance with ethical standards
Conflict of interest
Authors declare that they have no conflict of interest.
- Alonso R, Oñate-Sánchez L, Weltmeier F, Ehlert A, Diaz I, Dietrich K, Vicente-Carbajosa J, Dröge-Laser W (2009) A pivotal role of the basic leucine zipper transcription factor bZIP53 in the regulation of Arabidopsis seed maturation gene expression based on heterodimerization and protein complex formation. Plant Cell 21:1747–1761CrossRefPubMedPubMedCentralGoogle Scholar
- Amalraj A, Luang S, Kumar MY, Sornaraj P, Eini O, Kovalchuk N, Bazanova N, Li Y, Yang N, Eliby S, Langride P, Hrmova M, Lopato S (2016) Change of function of the wheat stress-responsive transcriptional repressor TaRAP2.1L by repressor motif modification. Plant Biotechnol J 14:820–832CrossRefPubMedGoogle Scholar
- Eini O, Yang N, Pyvovarenko T, Pillman K, Bazanova N, Tikhomirov N, Eliby S, Shirley N, Sivasankar S, Tingey S, Langridge P, Hrmova M, Lopato S (2013) Complex regulation by Apetala2 domain-containing transcription factors revealed through analysis of the stress-responsive TdCor410b promoter from durum wheat. PLoS ONE 8:e58713CrossRefPubMedPubMedCentralGoogle Scholar
- Fujita Y, Nakashima K, Yoshida T, Katagiri T, Kidokoro S, Kanamori N, Umezawa T, Fujita M, Maruyama K, Ishiyama K, Kobayashi M, Nakasone S, Yamada K, Ito T, Shinozaki K, Yamaguchi-Shinozaki K (2009) Three SnRK2 protein kinases are the main positive regulators of abscisic acid signaling in response to water stress in Arabidopsis. Plant Cell Physiol 50:2123–2132CrossRefPubMedGoogle Scholar
- Gonzalez-Guzman M, Pizzio GA, Antoni R, Vera-Sirera F, Merilo E, Bassel GW, Fernández MA, Holdsworth MJ, Perez-Amador MA, Kollist H, Rodriguez PL (2012) Arabidopsis PYR/PYL/RCAR receptors play a major role in quantitative regulation of stomatal aperture and transcriptional response to abscisic acid. Plant Cell 24:2483–2496CrossRefPubMedPubMedCentralGoogle Scholar
- Hrmova M, Lopato S (2014) Enhancing abiotic stress tolerance in plants by modulating properties of stress responsive transcription factors. In: Tuberosa R, Graner A, Frison E (eds) Genomics of plant genetic resources, vol 2, Part II: Crop productivity, food security and nutritional quality pp 291–316. Springer Verlag, Netherlands, ISBN 978-94-007-7574-9CrossRefGoogle Scholar
- Kobayashi Y, Murata M, Minami H, Yamamoto S, Kagaya Y, Hobo T, Yamamoto A, Hattori T (2005) Abscisic acid-activated SNRK2 protein kinases function in the gene-regulation pathway of ABA signal transduction by phosphorylating ABA response element-binding factors. Plant J 44:939–949CrossRefPubMedGoogle Scholar
- Uno Y, Furihata T, Abe H, Yoshida R, Shinozaki K, Yamaguchi-Shinozaki K (2000) Arabidopsis basic leucine zipper transcription factors involved in an abscisic acid-dependent signal transduction pathway under drought and high-salinity conditions. Proc Natl Acad Sci USA 97:11632–11637CrossRefPubMedPubMedCentralGoogle Scholar
- Yang Y, Luang S, Harris J, Riboni M, Li Y, Bazanova N, Hrmova M, Haefele S, Kovalchuk N, Lopato S (2017) Overexpression of the class I homeodomain transcription factor TaHDZipI-5 increases drought and frost tolerance in transgenic wheat. Plant Biotechnol J. https://doi.org/10.1111/pbi.12865 Google Scholar
- Yoshida T, Fujita Y, Sayama H, Kidokoro S, Maruyama K, Mizoi J, Shinozaki K, Yamaguchi-Shinozaki K (2010) AREB1, AREB2, and ABF3 are master transcription factors that cooperatively regulate ABRE-dependent ABA signaling involved in drought stress tolerance and require ABA for full activation. Plant J 61:672–685CrossRefPubMedGoogle Scholar
- Yoshida T, Fujita Y, Maruyama K, Mogami J, Todaka D, Shinozaki K, Yamaguchi-Shinozaki K (2015) Four Arabidopsis AREB/ABF transcription factors function predominantly in gene expression downstream of SnRK2 kinases in abscisic acid signalling in response to osmotic stress. Plant Cell Environ 38:35–49CrossRefPubMedGoogle Scholar