Genotypic differences in architectural and physiological responses to water restriction in rose bush

Abstract

The shape and, therefore, the architecture of the plant are dependent on genetic and environmental factors such as water supply. The architecture determines the visual quality, a key criterion underlying the decision to purchase an ornamental potted plant. The aim of this study was to analyze genotypic responses of eight rose bush cultivars to alternation of water restriction and re-watering periods, with soil water potential of -20 and -10 kPa respectively. Responses were evaluated at the architectural level through 3D digitalization using six architectural variables and at the physiological level by measuring stomatal conductance, water content, hormones [abscisic acid (ABA), auxin, cytokinins, jasmonic acid, and salicylic acid (SA)], sugars (sucrose, fructose, and glucose), and proline. Highly significant genotype and watering effects were revealed for all the architectural variables measured, as well as genotype × watering interaction, with three distinct genotypic architectural responses to water restriction – weak, moderate and strong – represented by Hw336, ‘Baipome’ and ‘The Fairy,’ respectively. The physiological analysis explained, at least in part, the more moderate architectural response of ‘Baipome’ compared to ‘The Fairy,’ but not that of Hw336 which is an interspecific hybrid. Such physiological responses in ‘Baipome’ could be related to: (i) the maintenance of the stimulation of budbreak and photosynthetic activity during water restriction periods due to a higher concentration in conjugated cytokinins (cCK) and to a lower concentration in SA; (ii) a better resumption of budbreak during the re-watering periods due to a lower concentration in ABA during this period. When associated with the six architectural descriptors, cCK, SA and ABA, which explained the genotypic differences in this study, could be used as selection criteria for breeding programs aimed at improving plant shape and tolerance to water restriction.

Ornamental plants architectural characteristics in relation to visual sensory attributes: a new approach on the rose bush for objective evaluation of the visual quality

“…commun.). Indeed, to observe plainly the Champagnat model (Hallé et al, 1978;Costes et al, 2014), 'Radrazz' has to develop relay and renewal shoots, seen up to now as reiterated complexes, but quite different from the 'elementary architectural structure stage' (Crespel et al, 2013;Li-Marchetti et al, 2015) and its development. Nonetheless, by definition, total reiteration does not lead to newest axis categories and thus should not be integrated to define neither the architectural model, nor the architectural unit.…”

“…Plant architecture recording was done using the PiafDigit software (Donès et al, 2006). It consisted of encoding with a Fastrack ® 3D digitizer (Polhemus, Colchester, VT, USA) the 3D coordinates of the phytomers constituting all apparent plant axes together with their topological relation (succession or branching) and some morphological features (Crespel et al, 2013;Morel et al, 2009Morel et al, , 2012Li-Marchetti et al, 2015). Branching order notation followed the 'birth' organization of the axes, i.e., the first axis sprouting from the cutting was denoted as the 1 st branching order, its lateral buds growth leading to second branching order axes and so on.…”

“…This primary structure was labeled in this study as the 'elementary architectural system'. Proximal axes sprouting at or under the substrate level, sometimes called 'renewal canes' (Zieslin and Mor, 1981) and empirically seen as total reiterated complexes (Costes et al, 2014;Kawamura et al, 2015) V o l u m e 8 3 | I s s u e 3 | J u n e 2 0 1 8 191 of an 'elementary architectural structure stage' (Crespel et al, 2013;Li-Marchetti et al, 2015), were denoted also as first branching order axes. These axes and all their descendants were further labeled as forming the 'delayed architectural systems'.…”

“…However, nowadays ornamental woody plants are still very often subjected to pruning or growth regulator applications to modulate plant growth for an empirical control of their quality. Knowledge about the variability of the architectural responses against environmental factors represents a valuable way to better control plant visual appearance with more reasoned, cheaper, and greener growing practices (Galopin et al, 2010;Huché-Thélier et al, 2011;Morel et al, 2012;Demotes-Mainard et al, 2013b;Crespel et al, 2014;Li-Marchetti et al, 2015). Understanding and controlling architecture is therefore an interesting lever to address ornamental plant design management, and more specifically to better fulfill expectations of the consumers thanks to knowledge about their requirements.…”

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

“…These new axes result from axillary bud outgrowth, a mechanism dependent on internal factors such as genetic background (Li-Marchetti et al, 2015) and plant metabolism such as plant hormones (Domagalska and Leyser, 2011), sugar signalling (Barbier et al, 2015;Mason et al, 2014) and sugar nutrition (Bonhomme et al, 2010;Girault et al, 2010). These traits are also regulated by external factors such as light quantity and quality , temperature (Djennane et al, 2014), water (DemotesMainard et al, 2013) and nitrogen availability (Huché-Thélier et al, 2011;Furet et al, 2014).…”