title: Apical dominance in saffron and the involvement of the branching enzymes CCD7 and CCD8 in the control of bud sprouting.
abstract: BACKGROUND
  In saffron (Crocus sativus), new corms develop at the base of every shoot developed from the maternal corm, a globular underground storage stem. Since the degree of bud sprouts influences the number and size of new corms, and strigolactones (SLs) suppress growth of pre-formed axillary bud, it was considered appropriate to investigate SL involvement in physiology and molecular biology in saffron. We focused on two of the genes within the SL pathway, CCD7 and CCD8, encoding carotenoid cleavage enzymes required for the production of SLs.
  
  
  RESULTS
  The CsCCD7 and CsCCD8 genes are the first ones isolated and characterized from a non-grass monocotyledonous plant. CsCCD7 and CsCCD8 expression showed some overlapping, although they were not identical. CsCCD8 was highly expressed in quiescent axillary buds and decapitation dramatically reduced its expression levels, suggesting its involvement in the suppression of axillary bud outgrowth. Furthermore, in vitro experiments showed also the involvement of auxin, cytokinin and jasmonic acid on the sprouting of axillary buds from corms in which the apical bud was removed. In addition, CsCCD8 expression, but not CsCCD7, was higher in the newly developed vascular tissue of axillary buds compared to the vascular tissue of the apical bud.
  
  
  CONCLUSIONS
  We showed that production and transport of auxin in saffron corms could act synergistically with SLs to arrest the outgrowth of the axillary buds, similar to the control of above-ground shoot branching. In addition, jasmonic acid seems to play a prominent role in bud dormancy in saffron. While cytokinins from roots promote bud outgrowth. In addition the expression results of CsCCD8 suggest that SLs could positively regulate procambial activity and the development of new vascular tissues connecting leaves with the mother corm.
authors.forename: Angela
authors.initials: A
authors.lastname: Rubio-Moraga
authors.forename: Oussama
authors.initials: O
authors.lastname: Ahrazem
authors.forename: Rosa M
authors.initials: RM
authors.lastname: Pérez-Clemente
authors.forename: Aurelio
authors.initials: A
authors.lastname: Gómez-Cadenas
authors.forename: Koichi
authors.initials: K
authors.lastname: Yoneyama
authors.forename: Juan Antonio
authors.initials: JA
authors.lastname: López-Ráez
authors.forename: Rosa Victoria
authors.initials: RV
authors.lastname: Molina
authors.affiliation: Departamento de Ciencia y Tecnología Agroforestal y Genética, Facultad de Farmacia, Instituto Botánico, Universidad de Castilla-La Mancha, Campus Universitario s/n, 02071 Albacete, Spain. marialourdes.gomez@uclm.es.
authors.forename: Lourdes
authors.initials: L
authors.lastname: Gómez-Gómez
mesh_terms: D015061:1,4-alpha-Glucan Branching Enzyme / Q000235:genetics / Q000378:metabolism*; D001681:Biological Assay; D027622:Crocus / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000502:physiology*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D018525:Germination / Q000187:drug effects / Q000235:genetics; D007783:Lactones / Q000378:metabolism; D018519:Meristem / Q000187:drug effects / Q000254:growth & development; D010802:Phylogeny; D010937:Plant Growth Regulators / Q000494:pharmacology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018520:Plant Shoots / Q000187:drug effects / Q000201:enzymology* / Q000254:growth & development*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
chemical_list: D007783:Lactones; D010937:Plant Growth Regulators; D010940:Plant Proteins; D012333:RNA, Messenger; D015061:1,4-alpha-Glucan Branching Enzyme