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Regulation of and by the Plant Cell Wall

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Front. Plant Sci. | doi: 10.3389/fpls.2018.01669

A new calmodulin-binding protein expresses in the context of secondary cell wall biosynthesis and impacts biomass properties in Populus

  • 1Biosciences Division, Oak Ridge National Laboratory, United States
  • 2Georgia Institute of Technology, United States
  • 3ArborGen LLC, United States
  • 4National Renewable Energy Laboratory (DOE), United States
  • 5Oak Ridge National Laboratory (DOE), United States

A greater understanding of biosynthesis, signaling and regulatory pathways involved in determining stem growth and secondary cell wall chemistry is important for enabling pathway engineering and genetic optimization of biomass properties. The present study describes a new functional role of PdIQD10, a Populus gene belonging to the IQ67-Domain1 family of IQD genes, in impacting biomass formation and chemistry. Expression studies showed that PdIQD10 has enhanced expression in developing xylem and tension-stressed tissues in Populus deltoides. Molecular dynamics simulation and yeast two-hybrid interaction experiments suggest interactions with two calmodulin proteins, CaM247 and CaM014, supporting the sequence-predicted functional role of the PdIQD10 as a calmodulin-binding protein. PdIQD10 was found to interact with specific Populus isoforms of the Kinesin Light Chain protein family, shown previously to function as microtubule-guided, cargo binding and delivery proteins in Arabidopsis. Subcellular localization studies showed that PdIQD10 localizes in the nucleus and plasma membrane regions. Promoter-binding assays suggest that a known master transcriptional regulator of secondary cell wall biosynthesis (PdWND1B) may be upstream of an HD-ZIP III gene that is in turn upstream of PdIQD10 gene in the transcriptional network. RNAi-mediated downregulation of PdIQD10 expression resulted in plants with altered biomass properties including higher cellulose, wall glucose content and greater biomass quantity. These results present evidence in support of a new functional role for an IQD gene family member, PdIQD10, in secondary cell wall biosynthesis and biomass formation in Populus.

Keywords: Secondary cell wall (SCW), Populus, Cellulose, signaling, Kinesin, Calcium-calmodulin, biomass, IQD

Received: 29 Jun 2018; Accepted: 26 Oct 2018.

Edited by:

Laura E. Bartley, University of Oklahoma, United States

Reviewed by:

Rui Shi, North Carolina State University, United States
Jenny C. Mortimer, Lawrence Berkeley National Laboratory (LBNL), United States  

Copyright: © 2018 Badmi, Payyavula, Bali, Guo, Jawdy, Gunter, Yang, Winkeler, Collins, Rottmann, Yee, Rodriguez Jr, Sykes, Decker, Davis, Ragauskas, Tuskan and Kalluri. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Udaya C. Kalluri, Oak Ridge National Laboratory (DOE), Oak Ridge, United States, kalluriudayc@ornl.gov