Role of ethylene and auxin in regenerative differentiation and orientation of tracheids in Pinus pinea seedlings

Abstract

A low auxin concentration (0.1% naphthalene acetic acid) induced tracheids with longitudinal polarity parallel to the hypocotyl axis in young Pinus pinea seedlings. Application of 0.1% ethrel laterally and 0.1% naphthalene acetic acid apically disturbed axial tracheid polarity and promoted the differentiation of tracheids with a lateral orientation. Ethrel by itself, with no auxin background, did not affect tracheid differentiation. Apical application of 1% gibberellic acid with the low auxin, reversed the polarity disorder induced by ethrel. Disturbance of axial tracheid polarity was observed under a high auxin concentration (0.5% naphthalene acetic acid) which was similar to the combined effect of ethrel and auxin. The high auxin concentration increased tracheid number significantly. This effect was curtailed following treatment with inhibitors of ethylene formation (Co# + ; 1-aminoethoxyvinylglycine) and action (Ag# + ). The role of ethylene in controlling the differentiation of radial tracheids, which characterize the vascular rays of pines, is discussed.

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

“…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). …”