A Novel System for Xylem Cell Differentiation in Arabidopsis thaliana

Abstract

During vascular development, procambial and cambial cells give rise to xylem and phloem cells. Because the vascular tissue is deeply embedded, it has been difficult to analyze the processes of vascular development in detail. Here, we establish a novel in vitro experimental system in which vascular development is induced in Arabidopsis thaliana leaf-disk cultures using bikinin, an inhibitor of glycogen synthase kinase 3 proteins. Transcriptome analysis reveals that mesophyll cells in leaf disks synchronously turn into procambial cells and then differentiate into tracheary elements. Leaf-disk cultures from plants expressing the procambial cell markers TDR(pro):GUS and TDR(pro):YFP can be used for spatiotemporal visualization of procambial cell formation. Further analysis with the tdr mutant and TDIF (tracheary element differentiation inhibitory factor) indicates that the key signaling TDIF-TDR-GSK3s regulates xylem differentiation in leaf-disk cultures. This new culture system can be combined with analysis using the rich material resources for Arabidopsis including cell-marker lines and mutants, thus offering a powerful tool for analyzing xylem cell differentiation.

Phosphosite charge rather than shootward localization determines OCTOPUS activity in root protophloem

“…So far the VISUAL assay was the only system in which we were able to isolate sufficient OPS protein for proteomic analyses, but even then abundance of individual OPS-derived peptides was low, precluding quantitative evaluation of a differential OPS phosphorylation state. In addition, the VISUAL transdifferentiation process, including OPS induction, is strictly dependent on the presence of bikinin (29,32), a GSK3/BIN2 inhibitor (33). Therefore, it is at present not possible to create differential BIN2 activity states in this system that would then allow quantitative assessment of OPS phosphorylation status.…”

Xylogenesis in zinnia (Zinnia elegans) cell cultures: unravelling the regulatory steps in a complex developmental programmed cell death event

“…The processes of transdifferentiation and the cellular demise are closely connected and proceed through well-concerted interplay of plant hormones, metabolic pathways, molecular and genetic factors. The recognition of the regulatory network of the TE differentiation cascade in the zinnia cell system has led to accumulation of significant amount of theoretical and experimental knowledge providing a platform for investigation of TE development in other cell cultures and xylem formation in planta (Basile et al 1973; Kuriyama and Fukuda 2000; Groover et al 1997; Roberts and McCann 2000; Dengler 2001; Kubo et al 2005; Oda et al 2005; Turner et al 2007; Jung et al 2008; Pesquet et al 2010; Bollhöner et al 2012; Demura 2014; Escamez and Tuominen 2014; Kondo et al 2015; Fukuda 2016). The implementation of the basic findings into practical aspects is expected to result in creation of plants with improved xylem properties related to plant survival under conditions of water stress and for production of biofuel and biomaterials.…”

“…These factors can impair the transdifferentiation if not properly considered (Supplemental File S2). The basic principles of the procedure for establishment of zinnia cell system have been developed for establishing xylogenic cultures of other species such Arabidopsis and for elaboration of new models for induction of xylogenesis on cultured leaf segments (Kubo et al 2005; Oda et al 2005; Turner et al 2007; Avci et al 2008; Jung et al 2008; de Rybel et al 2009, 2016; Ohashi-Ito et al 2010; Pesquet et al 2010, 2013; Bollhöner et al 2013; Schuetz et al 2013; Escamez and Tuominen 2014; Devillard and Walter 2014; Kondo et al 2015; Fukuda 2016). …”

“…A network of signalling interactions, metabolic pathways and gene and transcriptional factors involved in zinnia differentiation and PCD in vitro has been described also during xylem genesis in other cell and in planta model systems such as Arabidopsis thaliana , Populus, Pinus, Phyllostachys bamboo, Musa banana and others (Fukuda and Komamine 1980; Iwasaki et al 1986; Aloni 1987; Church and Galston 1989; Church 1993; Fukuda 1992, 1994, 1996, 1997, 2000, 2004, 2016; Kalev and Aloni 1998a, b; Yamamoto et al 1997, 2001, 2007; Krishnamurthy et al 1999; Kuriyama and Fukuda 2000; McCann 1997; Sachs 2000; Demura et al 2002; Pesquet et al 2003, 2004; 2013; Nieminen et al 2004; Kubo et al 2005; Turner et al 2007; Jung et al 2008; Motose et al 2009; Pesquet and Tuominen 2011; Ogita et al 2012; Bollhöner et al 2012; Milhinhos and Miguel 2013; Escamez and Tuominen 2014; Aloni 2015; Demura 2014; Didi et al 2015; Negi et al 2015; Růžika et al 2015; Kondo et al 2015). …”

Thinking Outside the Plant: Exploring Phloem Development Using VISUAL

“…Kondo et al (2016) developed a powerful system for analyzing phloem differentiation called VISUAL (Vascular Cell Induction Culture System Using Arabidopsis Leaves). In this system, mesophyll cells from Arabidopsis thaliana leaf discs or cotyledons are induced to form procambial cells, which then develop into xylem (Kondo et al, 2015) or phloem cells. To unlock the capacity of mesophyll cells to form vascular cells in vitro, including sieve element (SE)-like phloem cells and tracheary elements (xylem), the cells are treated with bikinin, an inhibitor of the kinase GSK3, which normally suppresses vascular tissue differentiation.…”