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The influence of lighting conditions, culture volume and four different auxins (indoleacetic acid (IAA), indolebutyric acid (IBA), 2,4-dichlorophenoxy- acetic acid (2,4-D) or 3-(benzo[b]selenyl)acetic acid (BSAA)) on Panax vietnamensis cell growth was evaluated in flasks. The highest biomass productivity was observed under continuous light and in the presence of IBA (0.36 g DW l−1 d−1) or BSAA (0.5 g DW|−1 d−1). Cultures in bioreactors were performed with these two auxins. The final biomass concentration was 107 g FW|−1 and 373 g FW|−1 in the presence of IBA or BSAA, respectively.

Lignification and xylem cell multiplication for wood formation were examined in in vitro propagated walnut shoot cuttings after transfer on an auxin- containing rooting medium for one week and subsequently during root development in vermiculite in the absence of growth regulators. Lignification in the shoot stems started immediately after the exogenous auxin treatment which implied changes in peroxidase activity and in free IAA levels. Sustained lignification required the completion of the following rooting phases. The lignin was exclusively located in xylem cells, the number of which increased with the number of developing roots. The mutual interactions between the aerial parts of the plants and their roots are discussed.

La regeneration in vitro de plants de Fraisier (Fragaria x ananassa Duch. cv. Elsanta) a partir de bourgeons adventifs stipulaires etait a l'origine de l'obtention d'un clone dont le comportement vegetatif et reproducteur in vivo s'est nettement distingue de celui de son homologue d'origine axillaire. Hormis la couleur claire et la forme arrondie de ses feuilles, ce nouveau clone se caracterise par un rythme plastochronal plus lent qui correspond aussi a la production d'un plus grand nombre de bourgeons axillaires sous forme de stolons. Au niveau floral, le receptacle est moins allonge et se trouve a la hauteur des etamines dont les antheres sont plus volumineuses que celles du clone axillaire. Ce dernier, dont le receptacle emerge au dela des etamines, presente une moins bonne pollinisation qui se traduit par une importante deformation des fruits, surtout en hiver et en l'absence d'agents pollinisateurs.

The PR-10 protein family contains proteins related to pathogenesis and allergenic proteins. They are acidic proteins, with an intracellular localization, usually members of a multigene family and ubiquitous among plant kingdom. They contain a highly conserved motif, identified as a phosphate binding site. Even if the biological function of these proteins is still unknown, many indicators seem to favour the hypothesis of an RNAse activity. Moreover, one of them seems to be a cytokinin specific binding protein. Besides, PR-10 protein expression induction under cytokinin treatment was observed with the Catharanthus roseus CrPR-10a protein. Here, we present the evidence of a significative increase of endogenous cytokinin contents in leaves of transgenic Tobacco plants over-expressing the CrPR-10a protein.