Sucrose synthase expression pattern in the rhythmically growing shoot of common oak (Quercus robur L.)

Abstract

-In the search for a trophic control of rhythmic growth of young oak seedlings, sucrose synthase accumulation, localization and activity were studied in the apex, underlying internodes and leaves, during the second flush of shoot growth. The use of an anti-SuSy antibody raised against the Vicia faba protein allowed the detection of SuSy, which showed a 90 kDa subunit. This antibody, used to immunolocalize the SuSy protein in oak revealed a positive signal in the reserve parenchyma tissues of the apex and in the leaf vascular tissues and underlying internodes. The study of SuSy activity along with the growth pattern of the different organs, suggested that SuSy may be involved in the control of rhythmic growth through the mobilization of sucrose in storage tissues and through loading/unloading processes. Such activities would help to bring enough nutrients to support the high morphogenic and growth processes during the rhythmic growth of the shoot.common oak / rhythmic growth / bud / sugar metabolism / sink strength Résumé -Localisation et activité de la saccharose synthase au cours de la croissance rythmique de l'axe aérien du chêne pédonculé (Quercus robur L.). Afin d'évaluer l'existence d'un contrôle trophique dans la croissance rythmique, l'accumulation, la localisation et l'activité de la saccharose synthase ont été étudiées au sein de l'apex, de l'entre-noeud sous-jacent et des feuilles au cours de la deuxième vague de croissance chez le chêne pédonculé. L'utilisation d'un anticorps anti-SuSy de Vicia faba a permis de détecter la protéine SuSy chez le chêne, qui présente une sous-unité de 90 kDa. Cet anticorps a révélé un signal positif dans les parenchymes de réserves de l'apex et dans les tissus vasculaires des feuilles et des entre-noeuds sous-jacents. L'étude de l'activité SuSy au cours de la croissance des différents territoires suggère que cette enzyme pourrait être impliquée dans le contrôle de la croissance rythmique au travers de la mobilisation des réserves glucidiques et des processus de chargement/déchargement phloémien. Ces activités apporteraient l'énergie nécessaire aux processus de morphogenèse et de croissance observés durant la croissance rythmique de la tige. chêne pédonculé / croissance rythmique / bourgeon / métabolisme glucidique / force de puits

Endogenous rhythmic growth in oak trees is regulated by internal clocks rather than resource availability

“…This high carbohydrate status is balanced by N acquisition, as indicated by increased 15 N excess and up-regulated ammonium and nitrate/peptide transporter expression. These results confirm findings of Le Hir et al (2005 a ), that sucrose synthase activity relates to shoot rhythmic growth in Q. robur seedlings. On Q. pubescens , Willaume and Pages (2011) hypothesized that the response of root growth to areal periodic growth is largely controlled by carbohydrate availability.…”

“…The massive transcript down-regulation in LRs during RGC indicates that plants’ physiological efforts are intensely biased towards the above-ground compartment during shoot flushing. At stage C, high resource consumption to build up the new shoot flush is confirmed by enrichment among up-regulated contigs of the leaf-specific GO terms ‘starch metabolic process’ and ‘sucrose transport’, and supports the finding of Le Hir et al (2005 a ) that mobilization of starch by conversion to sucrose in storage tissues supports the strong morphogenic processes during shoot development.…”

“…Initial studies on rhythmic growth in young oak seedlings focused on the shoot and the role of shifts in carbohydrate concentration ( Alaoui-Sossé et al , 1994 ). Le Hir et al (2005 a ) detected concomitance between shoot rhythmic growth and variations in sucrose synthase expression. They also related rhythmic shifts in sucrose concentration in apical tissues to alternating formation of normal and aborted leaves without lamina ( Le Hir et al , 2005 b ).…”

Sugars are under light control during bud burst in Rosa sp.

“…1999; Aue, Lecomte & Pétel 2000; Malus domestica , Brunel 2001). In breaking down starch or sucrose in simple sugars, enzymes such as amylases, sucrose synthase (Le Hir et al. 2005) and invertases (Maurel et al.…”