title: Influence of plant maturity, shoot reproduction and sex on vegetative growth in the dioecious plant Urtica dioica.
abstract: OBJECTIVE
  Stinging nettle (Urtica dioica) is a herbaceous, dioecious perennial that is widely distributed around the world, reproduces both sexually and asexually, and is characterized by rapid growth. This work was aimed at evaluating the effects of plant maturity, shoot reproduction and sex on the growth of leaves and shoots.
  
  
  METHODS
  Growth rates of apical shoots, together with foliar levels of phytohormones (cytokinins, auxins, absicisic acid, jasmonic acid and salicylic acid) and other indicators of leaf physiology (water contents, photosynthetic pigments, alpha-tocopherol and F(v)/F(m) ratios) were measured in juvenile and mature plants, with a distinction made between reproductive and non-reproductive shoots in both males and females. Vegetative growth rates were not only evaluated in field-grown plants, but also in cuttings obtained from these plants. All measurements were performed during an active vegetative growth phase in autumn, a few months after mature plants reproduced during spring and summer.
  
  
  RESULTS
  Vegetative growth rates in mature plants were drastically reduced compared with juvenile ones (48 % and 78 % for number of leaves and leaf biomass produced per day, respectively), which was associated with a loss of photosynthetic pigments (up to 24 % and 48 % for chlorophylls and carotenoids, respectively) and increases of alpha-tocopherol (up to 2.7-fold), while endogenous levels of phytohormones did not differ between mature and juvenile plants. Reductions in vegetative growth were particularly evident in reproductive shoots of mature plants, and occurred similarly in both males and females.
  
  
  CONCLUSIONS
  It is concluded that (a) plant maturity reduces vegetative growth in U. dioica, (b) effects of plant maturity are evident both in reproductive and non-reproductive shoots, but particularly in the former, and (c) these changes occur similarly in both male and female plants.
authors.affiliation: Departament de Biologia Vegetal, Facultat de Biologia, Universitat de Barcelona, E-08028 Barcelona, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Oñate
authors.forename: Sergi
authors.initials: S
authors.lastname: Munné-Bosch
mesh_terms: D000040:Abscisic Acid / Q000032:analysis; D002734:Chlorophyll / Q000032:analysis; D003517:Cyclopentanes / Q000032:analysis; D003583:Cytokinins / Q000032:analysis; D007210:Indoleacetic Acids / Q000032:analysis; D007541:Isopentenyladenosine / Q000031:analogs & derivatives / Q000032:analysis; D054883:Oxylipins / Q000032:analysis; D018515:Plant Leaves / Q000737:chemistry / Q000254:growth & development; D018520:Plant Shoots / Q000254:growth & development / Q000502:physiology; D012098:Reproduction / Q000502:physiology; D020156:Salicylic Acid / Q000032:analysis; D026982:Urtica dioica / Q000254:growth & development* / Q000502:physiology; D015026:Zeatin / Q000032:analysis; D024502:alpha-Tocopherol / Q000032:analysis
chemical_list: D003517:Cyclopentanes; D003583:Cytokinins; D007210:Indoleacetic Acids; D054883:Oxylipins; D002734:Chlorophyll; C011006:jasmonic acid; D000040:Abscisic Acid; D007541:Isopentenyladenosine; D015026:Zeatin; C009699:zeatin riboside; D024502:alpha-Tocopherol; D020156:Salicylic Acid