Shoot branching is an important aspect of plant architecture because it substantially affects plant biology and agricultural performance. Sugars play an important role in the induction of shoot branching in several species, including potato (Solanum tuberosum L.). However, the mechanism by which sugars affect shoot branching remains mostly unknown. In the present study, we addressed this question using sugar-mediated induction of bud outgrowth in potato stems under etiolated conditions. Our results indicate that sucrose feeding to detached stems promotes the accumulation of cytokinin (CK), as well as the expression of vacuolar invertase (VInv), an enzyme that contributes to sugar sink strength. These effects of sucrose were suppressed by CK synthesis and perception inhibitors, while CK supplied to detached stems induced bud outgrowth and VInv activity in the absence of sucrose. CK-induced bud outgrowth was suppressed in vinv mutants, which we generated by genome editing. Altogether, our results identify a branching-promoting module, and suggest that sugar-induced lateral bud outgrowth is in part promoted by the induction of CK-mediated VInv activity.

• MeSH
• cytokininy metabolismus   MeSH
• genetická variace MeSH
• geneticky modifikované rostliny růst a vývoj   metabolismus   MeSH
• genotyp MeSH
• mutace MeSH
• regulátory růstu rostlin metabolismus   MeSH
• sacharosa metabolismus   MeSH
• Solanum tuberosum růst a vývoj   metabolismus   MeSH
• výhonky rostlin růst a vývoj   metabolismus   MeSH
• zemědělské plodiny růst a vývoj   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH
• srovnávací studie MeSH
• Geografické názvy
• Izrael MeSH
• Názvy látek
• cytokininy MeSH
• regulátory růstu rostlin MeSH
• sacharosa MeSH

Cross-talk between phytohormones and sugars is intensely involved in plant metabolism, growth and regeneration. We documented alterations in cytokinin (CK) homeostasis in four developmental stages during de novo shoot organogenesis (DNSO) of kohlrabi (Brassica oleracea var. gongylodes cv. Vienna Purple) seedlings induced by exogenous CKs, trans-zeatin (transZ) and thidiazuron (TDZ), added together with elevated sucrose concentration (6% and 9%). Significant impact of CK and sucrose treatment and their interaction was recorded in all investigated stages, including plantlet development before calli formation (T1 and T2), calli formation (T3) and shoot regeneration (T4). Results showed remarkable increase in total CK levels for transZ treatment, particularly with 9% sucrose. This trend was observed for all physiological and structural groups of CKs. Application of TDZ contributed to little or no increase in CK levels regardless of sucrose concentration. Analysis of expression profiles of organogenesis-related genes involved in auxin transport, CK response, shoot apical meristem formation and cell division revealed that higher sugar concentration significantly downregulated the analysed genes, particularly in T3. This continued on TDZ, but transZ induced an opposite effect with 9% sucrose in T4, increasing gene activity. Our results demonstrated that phytohormone metabolism might be triggered by sucrose signalling in kohlrabi DNSO.

• MeSH
• Brassica genetika   růst a vývoj   metabolismus   MeSH
• fenylmočovinové sloučeniny farmakologie   MeSH
• homeostáza MeSH
• meristém účinky léků   genetika   růst a vývoj   MeSH
• regulace genové exprese u rostlin MeSH
• regulátory růstu rostlin farmakologie   MeSH
• rostlinné geny * MeSH
• sacharosa metabolismus   MeSH
• thiadiazoly farmakologie   MeSH
• zeatin farmakologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• fenylmočovinové sloučeniny MeSH
• regulátory růstu rostlin MeSH
• sacharosa MeSH
• thiadiazoly MeSH
• thidiazuron MeSH Prohlížeč
• zeatin MeSH

Bud outgrowth is controlled by environmental and endogenous factors. Through the use of the photosynthesis inhibitor norflurazon and of masking experiments, evidence is given here that light acts mainly as a morphogenic signal in the triggering of bud outgrowth and that initial steps in the light signaling pathway involve cytokinins (CKs). Indeed, in rose (Rosa hybrida), inhibition of bud outgrowth by darkness is suppressed solely by the application of CKs. In contrast, application of sugars has a limited effect. Exposure of plants to white light (WL) induces a rapid (after 3-6 h of WL exposure) up-regulation of CK synthesis (RhIPT3 and RhIPT5), of CK activation (RhLOG8), and of CK putative transporter RhPUP5 genes and to the repression of the CK degradation RhCKX1 gene in the node. This leads to the accumulation of CKs in the node within 6 h and in the bud at 24 h and to the triggering of bud outgrowth. Molecular analysis of genes involved in major mechanisms of bud outgrowth (strigolactone signaling [RwMAX2], metabolism and transport of auxin [RhPIN1, RhYUC1, and RhTAR1], regulation of sugar sink strength [RhVI, RhSUSY, RhSUC2, and RhSWEET10], and cell division and expansion [RhEXP and RhPCNA]) reveal that, when supplied in darkness, CKs up-regulate their expression as rapidly and as intensely as WL Additionally, up-regulation of CKs by WL promotes xylem flux toward the bud, as evidenced by Methylene Blue accumulation in the bud after CK treatment in the dark. Altogether, these results suggest that CKs are initial components of the light signaling pathway that controls the initiation of bud outgrowth.

• MeSH
• biologické modely MeSH
• časové faktory MeSH
• cytokininy metabolismus   farmakologie   MeSH
• meristém genetika   růst a vývoj   metabolismus   MeSH
• polymerázová řetězová reakce s reverzní transkripcí MeSH
• regulace genové exprese u rostlin účinky léků   účinky záření   MeSH
• regulátory růstu rostlin metabolismus   farmakologie   MeSH
• Rosa genetika   růst a vývoj   metabolismus   MeSH
• rostlinné proteiny genetika   metabolismus   MeSH
• signální transdukce účinky léků   genetika   účinky záření   MeSH
• světlo * MeSH
• tma MeSH
• výhonky rostlin genetika   růst a vývoj   metabolismus   MeSH
• vývojová regulace genové exprese účinky léků   účinky záření   MeSH
• xylém genetika   růst a vývoj   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• cytokininy MeSH
• regulátory růstu rostlin MeSH
• rostlinné proteiny MeSH