Asparagine and sugars are both required to sustain secondary axis elongation after bud outgrowth in Rosa hybrida

BRANCHED1: A Key Hub of Shoot Branching

“…In Rosaceae as in many woody plants, nitrate is reduced and assimilated into amino acids directly in the roots; consequently, asparagine, arginine, aspartate, and glutamine are the main forms of nitrogen translocated to the buds via the xylem sap (Millard et al, 1998; Malaguti et al, 2001; Grassi et al, 2002; Guak et al, 2003; Le Moigne et al, 2018). In rose, asparagine is a major nitrogen form involved in bud outgrowth (Le Moigne et al, 2018); this is in accordance with previous data showing that application of asparagine on the soil of olive trees or on the leaves of poplar trees contributed to enhance bud outgrowth and secondary axis elongation (Proietti and Tombesi, 1996; Cline et al, 2006). In rice, a lack of cytosolic glutamine synthetase1;2 in the vascular tissues of axillary buds severely reduced their outgrowth (Funayama et al, 2013; Ohashi et al, 2015) independently of the SL level (Ohashi et al, 2015).…”

“…In rice, a lack of cytosolic glutamine synthetase1;2 in the vascular tissues of axillary buds severely reduced their outgrowth (Funayama et al, 2013; Ohashi et al, 2015) independently of the SL level (Ohashi et al, 2015). In rose bush, sucrose, glucose, and fructose had to be associated to asparagine to allow for the buds to grow out in vitro (Le Moigne et al, 2018). This effect involved the upregulation of IPT3 gene expression in the stem and in the vicinity of the bud (Le Moigne et al, 2018) and the downregulation of BRC1 (Barbier et al, 2015).…”

“…In rose bush, sucrose, glucose, and fructose had to be associated to asparagine to allow for the buds to grow out in vitro (Le Moigne et al, 2018). This effect involved the upregulation of IPT3 gene expression in the stem and in the vicinity of the bud (Le Moigne et al, 2018) and the downregulation of BRC1 (Barbier et al, 2015). In addition to a nutritional role, asparagine might also be a signal representing the nitrogen status of the plant, so as to counteract BRC1 expression through CK stimulation.…”

“…The currently accepted idea supports that endogenous, developmental, and environmental inputs converge into bud-located integrators, which are at the head of a network of mechanisms governing the ability of buds to grow out. Among these inputs, hormones, sugar, nitrogen, light, and water play a determining role in shoot branching regulation (McSteen, 2009; González-Grandío et al, 2013; Niwa et al, 2013; Li-Marchetti et al, 2015; Rameau et al, 2015; Teichmann and Muhr, 2015; Corot et al, 2017; Le Moigne et al, 2018). Those factors may influence shoot branching via various physiological and molecular mechanisms, targeting different branching-related genes and acting synergistically or antagonistically.…”

Sucrose promotes etiolated stem branching through activation of cytokinin accumulation followed by vacuolar invertase activity

“…Shoot branching is controlled by complex interactions among hormones, nutrients, and environmental cues (Ongaro et al, 2008; Müller and Leyser, 2011; Leduc et al, 2014; Barbier et al, 2015b; Rameau et al, 2015; Roman et al, 2016; Fichtner et al, 2017; Le Moigne et al, 2018). Auxin, strigolactones and cytokinins (CKs) are the main plant hormones involved in the regulation of bud outgrowth, forming a systemic network that orchestrates this process (Ferguson & Beveridge, 2009).…”