ELSEVI ER Plant Science 127 (1997) 39-51 Photosynthetic ability of in vitro grown coconut zy (Cocus nucifera L.) plantlets derived from zygotic embryos Karine Triques zyxwvu a , Alain Rival a,*, Thierry Bedé a, Michel Puard zyx b, Jacques Roy zy ‘, Aimé Nato d, Danièle Lavergne d, Michel Havaux zyxw e, Jean-Luc Verdeil a , Alassane Sangare ‘, Serge Hamon a a ORSTOM-CIRAD, Laboratoire de Ressources Génétiques et Amélioration des Plantes Tropicales, 91 1 Avenue d’Agropolis, BP 5045, F-34 032 Montpellier Cedex 01, France CIRAD-CA, UR Fonctioïtneinent du Peuplement Végétal, BP 5035, F-34 032 Montpellier Cedex 01, France CNRS, Centre d’Ecologie Fonctionnelle et Evolutive, F-34293 Montpellier Cedex 05, France Université de Paris XI, Ceïitre d‘Orsay, Laboratoire de Morphogenèse Végétale Expérinientale, Bat. 360, F-91405 Orsay, France zy e CEA Sciences du Vivant, Départeineïit d’Ecopliysiologie Végétale et de Microbiologie, Ceritre d‘Etudes de Cadarache, F-I3 108 Saint Paul lez Durance, Frame ‘ IDEFOR-DPO, Station Marc Delorme, Port Bou&?, 07 BP13, Abiajan 07, Côte d’Ivoire Received 11 March 1997; accepted 30 April 1997 zyxwv Abstract Photosynthetic parameters have been investigated using complementary approaches throughout the in vitro development of coconut zygotic embryos into plantlets. Patterns of chlorophyll fluorescence were comparable in in vitro grown coconut plantlets (OFAx = 0.72 and O, = 0.45) and in autotrophic adult palms zyx (OpAX = 0.76 and Bp=0.5O). Chlorophyll content was lower in in vitro-cultured plantlets (0.92 mg/g fresh weight (FW)) than in autotrophic plants (2.43 mg/g FW). The photosynthetic rate (1.14 pmol CO,/m’ per s) of autotrophic palms was half that of in vitro grown plantlets, while transpiration rates were similar in both. Changes in the PEPC:RubisCO ratio during the development of in vitro grown plantlets (from 89.17 to 0.04 pmol COJh per mg total soluble protein (TSP)) reflected a transition from a heterotrophic towards a RubisCO-mediated mode of CO, fixation. The RubisCO enzyme capacity (2.83 pmol CO,/h per mg TSP) and content (172.8 mg/g TSP) measured in in vitro-cultured plantlets were lower than those measured in autotrophic palms (6.60 pmol CO,/h per mg TSP and 217.6 mg/g TSP respectively). Transmission electronic microscopy (TEM) observations showed a complete ultrastructural organisation of chloroplasts in plantlets at the end of the in vitro culture process (6 weeks under light). All the studied parametersj Abbreoiatiotis: Chl a, Chlorophyll a; Chl b, Chlorophyll b; FW, Fresh weight; PAR, Photosynthesis active radiations; PEPC, Phosphoenolpyruvate carboxylase; PVP, Polyvinyl pyrrolidone; RH, Relative humidity; RubisCO, Ribulose 1,5-bisphosphate carboxylase oxygenase; To, Temperature; TCA cycle, Tricarboxylic acid or Krebs cycle; TEM, Transmission electronic microscopy; TSP, Total soluble proteins. * Corresponding author. E-mail: rival@orstom.fr 0168-9452/97/$17.00 O 1997 Elsevier Science Ireland Ltd. All rights reserved. PII SO168-9452(97)00113-1