Chatfield SP, Capron R, Severino A, Penttila PA, Alfred S, Nahal H, Provart NJ
Plant J. 2012 Nov;:
PubMed PMID: 23181633
Abstract
Adventitious shoot organogenesis contributes to the fitness of diverse plant species, and control of this process is a vital step in plant transformation and in vitro propagation. New shoot meristems (SMs) can be induced by conversion of lateral root primorida/meristems (LRP/LRMs) or callus expressing markers for this identity. To study this important and fascinating process we developed a high-throughput methodology for synchronous initiation of LRP by auxin, and subsequent cytokinin-induced conversion of these LRP to SMs. Cytokinin treatment induces expression of the shoot meristematic gene WUSCHEL (WUS) in converting LRP (cLRP) within 24-30 hours, and WUS is required for LRP-SM conversion. Subsequently, a transcriptional reporter for CLAVATA3 (CLV3) appeared 32-48 hours after transfer to cytokinin, marking presumptive shoot stem cells at the apex of cLRP. Thus the spatial expression of these two components (WUS and CLV3) of a regulatory network maintaining SM stem cells already resembles that seen in a vegetative SAM, suggesting very rapid initiation and establishment of the new SMs. Our high-throughput methodology enabled us to successfully apply a systems approach to the study of plant regeneration. Herein we characterize transcriptional reporter expression and global gene expression changes during LRP-SM conversion, elaborate the role of WUS and WUS-responsive genes in the conversion process, identify and test putative functional targets, perform a comparative analysis of domain specific expression in cLRP and SM tissue, and develop a bioinformatic tool for examining gene expression in diverse regeneration systems. © 2012 The Authors. The Plant Journal © 2012 Blackwell Publishing Ltd.