Research


Shashank Pandey is standing in a greenhouse with small aspen trees on a table in front of him and taller ones behind him, he is looking straight in the cameraPhoto: Jasim Basheer

The DECORE project aims to uncover mechanisms by which low temperature controls bud dormancy in hybrid aspen. Recent research in our lab identified AGL8 as a transcription factor involved in the release of bud dormancy. Building on this, we hypothesize that AGL8 regulates gibberellin, the mobile signaling component FT1, and intercellular communication to coordinate the release of bud dormancy.

Plants have an astonishing ability to sense and respond to environmental cues, including seasonal changes. One critical but poorly understood aspect of this responsiveness is the regulation of bud dormancy in trees, a phenomenon central to their survival and growth in temperate regions. My MSCA research, focusing on the experimental model tree hybrid aspen, endeavours to shed light on the intricate mechanisms behind the control of plant development by seasonal cues, especially those related to temperature-mediated bud dormancy.

In temperate and boreal regions, perennial plants experience temperature extremes, from freezing winters to warm summers. To survive, they employ sophisticated mechanisms that detect seasonal variations and adjust their growth accordingly (Fig 1). In late summer, short days trigger the cessation of growth and protect the shoot apical meristem (SAM) and leaf primordia in a bud from winter damage. Dormancy is established to prevent early growth activation until favourable conditions return in spring. As spring arrives, dormancy is released, enabling bud break and initiating the growth cycle (Fig 1). However, the molecular mechanism underlying bud dormancy release has remained a mystery. Recent research has uncovered a novel mechanism involving the control of cell-cell communication via plasmodesmata (PDs), which are intercellular channels responsible for the trafficking of growth regulators. This dynamic regulation of PDs plays a vital role in bud dormancy.

Schematic overview about the dormancy cycle in the apex of aspen: five photos arranged in a circle with arrows inbetween llustrate how the apex looks like at the different stages during the season. Additional information describing the stage of the respective stage is added to each arrow. Fig. 1: Seasonal changes occurring in the apex of hybrid aspen during dormancy
Under long-day (LD) and warm temperature (WT) conditions in the summer, trees grow actively and stop their growth upon sensing short-days (SDs) during early autumn. SDs induce dormancy in the buds in late autumn. Chilling temperatures (LT) during the winter periods promote the release of dormancy. Relatively warmer temperature in the spring promotes the bud burst, followed by active growth again in the summer.

The identification of key genes and factors, including AGL8, FT1, GA-20 oxidase, and the callose-degrading enzyme GH17, as downstream targets of AGL8, provides a unique opportunity to unravel the relationship between gene regulation, hormonal changes, cell-cell communication (via PDs), and their combined role in temperature-mediated bud dormancy control. Based on this, the research project has below objectives:

Elucidating the role of AGL8-mediated FT1 activation in inducing the release of bud dormancy

This objective aims to investigate if FT1 is a downstream target of AGL8 and if so, uncover the significance of FT1 regulation by AGL8 in the release of bud dormancy (Fig. 2). This objective involves utilization of Chromatin Immuno-Precipitation PCR (ChIP-PCR) technique to probe the interaction between AGL8 and the FT1 promoter, which is essential for confirming AGL8 binding to the FT1 promoter. Next, AGL8-overexpressing plants carrying FT1 loss-of-function mutations (AGL8ox/ft1) will be created using CRISPR-Cas9 technology. Finally, dormancy release in the AGL8ox/ft1 double mutant and the AGL8-overexpressing parental line (AGL8ox) is compared using controlled growth conditions, simulating transitions to autumn and winter followed by bud break observation.

Determination of AGL8’s role in hormonal control of bud dormancy release in response to temperature cues

This objective delves into the role of AGL8 in regulating gibberellic acid (GA) biosynthesis, a key hormonal factor influencing bud dormancy release (Fig. 2). It involves measurement of GA levels in buds from wild-type (wt), AGL8-overexpressing (AGL8ox), and AGL8-RNAi plants after dormancy release to assess AGL8's impact on GA biosynthesis. Following that, we will introduce cDNA for GA-2 oxidase, a GA-degrading enzyme, into WT and AGL8ox hybrid aspen plants. Then we will analyse dormancy release in WT and AGL8ox lines expressing GA-2 oxidase under controlled growth conditions to determine the role of GA in low-temperature-induced dormancy release. The expected outcomes of these investigations include insights into AGL8's role as a regulator of GA biosynthesis and its significance in controlling dormancy release in response to low temperatures.

Uncovering the role of AGL8-regulated PD opening in bud dormancy release

It focuses on the role of PDs and their connection to bud dormancy (Fig. 2). We aim to understand if AGL8, a key gene identified in our research, activates GH17, an enzyme linked to the breakdown of callose, which in turn opens the PDs, enabling dormancy release by employing employ transmission electron microscopy and immunogold labelling approaches.

Scheme illustrating the key objectives of the research project: Identifying how low temperature regulates dormancy release through AGL8 FT1 activation (objective !), GA biosynthesis (objective 2) and opening of plasmodesmata (objective 3)Fig. 2: Key project objectives to elucidate the dormancy release.

In summary, this research project seeks to unravel the mysteries behind bud dormancy in trees by investigating the interactions between genes, hormones, and cell-cell communication. The findings will not only advance our understanding of how plants adapt to seasonal changes but will also contribute to the competitiveness of European research, particularly in the field of developmental adaptation to seasonal variations.  

Logo of Marie Skłodowska-Curie ActionsThis project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 101025929.

  2024 (1)
Molecular Advances of Bud Dormancy in Trees. Ding, J., Wang, K., Pandey, S., Perales, M., Allona, I., Khan, M. R. I., Busov, V. B, & Bhalerao, R. P Journal of Experimental Botany,erae183. April 2024.
Molecular Advances of Bud Dormancy in Trees [link]Paper   doi   link   bibtex   abstract  
  2023 (1)
LBD18 and IAA14 antagonistically interact with ARF7 via the invariant Lys and acidic residues of the OPCA motif in the PB1 domain. Nguyen, U. T., Pandey, S. K., & Kim, J. Planta, 258(2): 26. June 2023.
LBD18 and IAA14 antagonistically interact with ARF7 via the invariant Lys and acidic residues of the OPCA motif in the PB1 domain [link]Paper   doi   link   bibtex   abstract  
  2022 (1)
Understanding the Modus Operandi of Class II KNOX Transcription Factors in Secondary Cell Wall Biosynthesis. Nookaraju, A., Pandey, S. K., Ahlawat, Y. K., & Joshi, C. P. Plants, 11(4): 493. January 2022. Number: 4 Publisher: Multidisciplinary Digital Publishing Institute
Understanding the Modus Operandi of Class II KNOX Transcription Factors in Secondary Cell Wall Biosynthesis [link]Paper   doi   link   bibtex   abstract  
  2021 (1)
Recent advances in peptide signaling during Arabidopsis root development. Jeon, B. W., Kim, M., Pandey, S. K, Oh, E., Seo, P. J., & Kim, J. Journal of Experimental Botany, 72(8): 2889–2902. April 2021.
Recent advances in peptide signaling during Arabidopsis root development [link]Paper   doi   link   bibtex   abstract  
  2019 (2)
LBD13 positively regulates lateral root formation in Arabidopsis. Cho, C., Jeon, E., Pandey, S. K., Ha, S. H., & Kim, J. Planta, 249(4): 1251–1258. April 2019.
LBD13 positively regulates lateral root formation in Arabidopsis [link]Paper   doi   link   bibtex   abstract  
LBD16 and LBD18 acting downstream of ARF7 and ARF19 are involved in adventitious root formation in Arabidopsis. Lee, H. W., Cho, C., Pandey, S. K., Park, Y., Kim, M., & Kim, J. BMC Plant Biology, 19(1): 46. January 2019.
LBD16 and LBD18 acting downstream of ARF7 and ARF19 are involved in adventitious root formation in Arabidopsis [link]Paper   doi   link   bibtex   abstract  
  2018 (2)
Coiled-coil motif in LBD16 and LBD18 transcription factors are critical for dimerization and biological function in arabidopsis. Pandey, S. K., & Kim, J. Plant Signaling & Behavior, 13(1): e1411450. January 2018. Publisher: Taylor & Francis _eprint: https://doi.org/10.1080/15592324.2017.1411450
Coiled-coil motif in LBD16 and LBD18 transcription factors are critical for dimerization and biological function in arabidopsis [link]Paper   doi   link   bibtex   abstract  
LBD18 uses a dual mode of a positive feedback loop to regulate ARF expression and transcriptional activity in Arabidopsis. Pandey, S. K., Lee, H. W., Kim, M., Cho, C., Oh, E., & Kim, J. The Plant Journal, 95(2): 233–251. 2018. _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/tpj.13945
LBD18 uses a dual mode of a positive feedback loop to regulate ARF expression and transcriptional activity in Arabidopsis [link]Paper   doi   link   bibtex   abstract  
  2017 (1)
Dimerization in LBD16 and LBD18 Transcription Factors Is Critical for Lateral Root Formation. Lee, H. W., Kang, N. Y., Pandey, S. K., Cho, C., Lee, S. H., & Kim, J. Plant Physiology, 174(1): 301–311. May 2017.
Dimerization in LBD16 and LBD18 Transcription Factors Is Critical for Lateral Root Formation [link]Paper   doi   link   bibtex   abstract  
  2016 (2)
Expression and Protein Interaction Analyses Reveal Combinatorial Interactions of LBD Transcription Factors During Arabidopsis Pollen Development. Kim, M., Kim, M., Pandey, S., & Kim, J. Plant and Cell Physiology, 57(11): 2291–2299. November 2016.
Expression and Protein Interaction Analyses Reveal Combinatorial Interactions of LBD Transcription Factors During Arabidopsis Pollen Development [link]Paper   doi   link   bibtex   abstract  
Virus-induced gene silencing (VIGS)-mediated functional characterization of two genes involved in lignocellulosic secondary cell wall formation. Pandey, S. K., Nookaraju, A., Fujino, T., Pattathil, S., & Joshi, C. P. Plant Cell Reports, 35(11): 2353–2367. November 2016.
Virus-induced gene silencing (VIGS)-mediated functional characterization of two genes involved in lignocellulosic secondary cell wall formation [link]Paper   doi   link   bibtex   abstract  
  2014 (1)
Enhanced accumulation of fatty acids and triacylglycerols in transgenic tobacco stems for enhanced bioenergy production. Nookaraju, A., Pandey, S. K., Fujino, T., Kim, J. Y., Suh, M. C., & Joshi, C. P. Plant Cell Reports, 33(7): 1041–1052. July 2014.
Enhanced accumulation of fatty acids and triacylglycerols in transgenic tobacco stems for enhanced bioenergy production [link]Paper   doi   link   bibtex   abstract  
  2013 (1)
Designing Cell Walls for Improved Bioenergy Production. Nookaraju, A., Pandey, S. K., Bae, H., & Joshi, C. P. Molecular Plant, 6(1): 8–10. January 2013.
Designing Cell Walls for Improved Bioenergy Production [link]Paper   doi   link   bibtex  
  2012 (2)
Plant disease resistance genes: Current status and future directions. Gururani, M. A., Venkatesh, J., Upadhyaya, C. P., Nookaraju, A., Pandey, S. K., & Park, S. W. Physiological and Molecular Plant Pathology, 78: 51–65. April 2012.
Plant disease resistance genes: Current status and future directions [link]Paper   doi   link   bibtex   abstract  
Role of Ca2+-mediated signaling in potato tuberization: An overview. Nookaraju, A., Pandey, S., Upadhyaya, C., Heung, J. J., Kim, H. S, Chun, S. C., Kim, D. H., & Park, S. W. Botanical Studies, 53: 177–189. 2012.
Role of Ca2+-mediated signaling in potato tuberization: An overview [link]Paper   link   bibtex   abstract  
  2011 (1)
An Update on Biotechnological Approaches for Improving Abiotic Stress Tolerance in Tomato. Pandey, S. K., Nookaraju, A., Upadhyaya, C. P., Gururani, M. A., Venkatesh, J., Kim, D., & Park, S. W. Crop Science, 51(6): 2303–2324. 2011. _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.2135/cropsci2010.10.0579
An Update on Biotechnological Approaches for Improving Abiotic Stress Tolerance in Tomato [link]Paper   doi   link   bibtex   abstract  
  2010 (1)
Molecular approaches for enhancing sweetness in fruits and vegetables. Nookaraju, A., Upadhyaya, C. P., Pandey, S. K., Young, K. E., Hong, S. J., Park, S. K., & Park, S. W. Scientia Horticulturae, 127(1): 1–15. November 2010.
Molecular approaches for enhancing sweetness in fruits and vegetables [link]Paper   doi   link   bibtex   abstract