Sugar availability suppresses the auxin‐induced strigolactone pathway to promote bud outgrowth

• DOI: 10.1111/nph.16201
• Publication Date: 2019-09-17T15:33:12Z
• Authors: Jessica Bertheloot; François Barbier; Frédéric Boudon; Maria Dolores Per...; Thomas Péron; Sylvie Citerne; Elizabeth Dun; Christine Beveridge; Christophe Godin; Soulaiman Sakr
• Keywords: 0301 basic medicine; 570; Sucrose; Cytokinins; Physiology; F60 - Physiologie et biochimie végétale; http://aims.fao.org/aos/agrovoc/c_5968; F62 - Physiologie végétale - Croissance et développement; Plant Science; strigolactones; Flowers; Rosa; Models, Biological; Lactones; 03 medical and health sciences; 1110 Plant Science; branching; [SDV.BV]Life Sciences [q-bio]/Vegetal Biology; [SDV.BV] Life Sciences [q-bio]/Vegetal Biology; Pisum sativum; 580; 0303 health sciences; model; hormones; Indoleacetic Acids; bourgeon; sucrose; 1314 Physiology; bud; [SDV.BV.AP]Life Sciences [q-bio]/Vegetal Biology/Plant breeding; sucre; sugar; Mutation; [SDV.BV.AP] Life Sciences [q-bio]/Vegetal Biology/Plant breeding; http://aims.fao.org/aos/agrovoc/c_1135; substance de croissance végétale; auxin; Sugars; http://aims.fao.org/aos/agrovoc/c_7498

Summary

Apical dominance occurs when the growing shoot tip inhibits the outgrowth of axillary buds. Apically‐derived auxin in the nodal stem indirectly inhibits bud outgrowth via cytokinins and strigolactones. Recently, sugar deprivation was found to contribute to this phenomenon. Using rose and pea, we investigated whether sugar availability interacts with auxin in bud outgrowth control, and the role of cytokinins and strigolactones, in vitro and in planta. We show that sucrose antagonises auxin’s effect on bud outgrowth, in a dose‐dependent and coupled manner. Sucrose also suppresses strigolactone inhibition of outgrowth and the rms3 strigolactone‐perception mutant is less affected by reducing sucrose supply. However, sucrose does not interfere with the regulation of cytokinin levels by auxin and stimulates outgrowth even with optimal cytokinin supply. These observations were assembled into a computational model in which sucrose represses bud response to strigolactones, largely independently of cytokinin levels. It quantitatively captures our observed dose‐dependent sucrose‐hormones effects on bud outgrowth and allows us to express outgrowth response to various combinations of auxin and sucrose levels as a simple quantitative law. This study places sugars in the bud outgrowth regulatory network and paves the way for a better understanding of branching plasticity in response to environmental and genotypic factors.