<p> Genome-wide analysis unravelling the puzzle of phytohormones acting in concert during storage root initiation of cassava</p><p>Punchapat Sojikul 1 *, Treenut Saithong2, Saowalak Kalapanulak2, Nuttapat Pisuttinusart3, Siripan Limsirichaikul3, Maho Tanaka4, Yoshinori Utsumi4, Tetsuya Sakurai5, Motoaki Seki4, and Jarunya Narangajavana1</p><p>1) Center for Cassava Molecular Biotechnology, Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand 2) Bioinformatics and Systems Biology Program, School of Bioresources and Technology; Systems Biology and Bioinformatics Laboratory, Pilot Plant Development and Training Institute, King Mongkut’s University of Technology, Thonburi, Thailand 3) Department of Biopharmacy, Faculty of Pharmacy, Silpakorn University, Nakhon Pathom, Thailand 4) Plant Genomic Network Research Team, RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, Japan 5) Integrated Genome Informatics Research Unit, RIKEN Plant Science Center, Yokohama, Kanagawa, Japan *[email protected], Registrant ID# 0001</p><p>In storage root developmental process, a phase change from cell division and elongation to radial growth and accumulation of reserve substances such as starch is observed. In this study, transcription profiling of fibrous, intermediate and storage roots at 8-week-olds were investigated using a 60-mer-oligo microarray. The key regulating processes during the transition stage from fibrous to intermediate roots were transcription and gene expression. Whereas, the key regulating processes during intermediate roots to storage roots were homeostasis and signal transduction. Clustering analysis of significant genes indicated that phytohormone-related transcription factors were differentially expressed. A network of correlative nodes showed the relationship between KNOX1 and phytohormones during storage root initiation. Exogeneous treatment of phytohormones N6-benzylaminopurine (BAP) and 1-Naphthaleneacetic acid (NAA) were then used to investigate differential gene expressions at the storage root initiation stage. The results suggest that phytohormones are acting in concert to regulate the onset of cassava storage root development. In addition, when the root tip becomes swollen, the diminished of MeAGL20 and upregulated of MeCDPK might play important roles at the onset of storage root initiation. </p><p>Sojikul, P., Saithong, T., Kalapanulak, S., Pisuttinusart, N., Limsirichaikul, S., Tanaka, M., Utsumi, Y., Sakurai, T., Seki, M. and Narangajavana, J. (2015) Genome-wide analysis reveals phytohormone action during cassava storage root initiation. Plant Mol. Biol., 1-13. DOI:10.1007/s11103-015-0340-z</p>