Co-expression network of transcription factors reveal ethylene-responsive element-binding factor as key regulator of wood phenotype in Eucalyptus tereticornis
Suitability of wood biomass for pulp production is dependent on the cellular architecture and composition of secondary cell wall. Presently, systems genetics approach is being employed to understand the molecular basis of trait variation and co-expression network analysis has enabled holistic understanding of complex trait such as secondary development. Transcription factors (TFs) are reported as key regulators of meristematic growth and wood formation. The hierarchical TF network is a multi-layered system which interacts with downstream structural genes involved in biosynthesis of cellulose, hemicelluloses and lignin. Several TFs have been associated with wood formation in tree species such as Populus, Eucalyptus, Picea and Pinus. However, TF-specific co-expression networks to understand the interaction between these regulators are not reported. In the present study, co-expression network was developed for TFs expressed during wood formation in Eucalyptus tereticornis and ethylene-responsive element-binding factor, EtERF2, was identified as the major hub transcript which co-expressed with other secondary cell wall biogenesis-specific TFs such as EtSND2, EtVND1, EtVND4, EtVND6, EtMYB70, EtGRAS and EtSCL8. This study reveals a probable role of ethylene in determining natural variation in wood properties in Eucalyptus species. Understanding this transcriptional regulation underpinning the complex bio-processing trait of wood biomass will complement the Eucalyptus breeding program through selection of industrially suitable phenotypes by marker-assisted selection.
KeywordsCo-expression network Ethylene Regulation Transcription factor Wood formation
We acknowledge the guidance given by Dr. Jennifer Dewoody, National Forest Genetics Laboratory, USDA Forest Service, Placerville, CA; Dr. Sucheta Tripathy, Structural Biology and Bio-informatics Division, Indian Institute of Chemical Biology, Kolkata, India; Dr. Saravanakumar Selvaraj, Centre for Pharmacology and Toxicology, Hannover Medical School, Hannover, Germany, and Dr. Gayatri Ramakrishnan, Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India, for developing gene regulatory networks. The funding for the research work was provided to Dr. Modhumita Ghosh Dasgupta by Department of Biotechnology, Government of India, under the research project with grant number BT/PR10055/PBD/16/772/2007. The funding support as research fellowship was provided to Dr. Veeramuthu Dharanishanthi by Department of Biotechnology, Government of India.
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Conflict of interest
On behalf of all authors, the corresponding author states that there is no conflict of interest.
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