Effets de deux sources lumineuses sur la croissance et sur le contenu glucidique et gibbérellinique des feuilles de Cichorium intybus L cultivé in vitro

Des plantules de Cichorium intybus L (cv Flash) cultivées in vitro sont exposées à la lumière fournie soit par des lampes Cool-White, soit par des lampes Gro-Lux. Le développement du feuillage, de même que son contenu en gibbérellines et en glucides alcoolo-solubles sont modifiés par le type d'éclairement. Les lampes Cool-White permettent d'obtenir des feuilles plus grandes et plus riches en gibbérellines. Sous lumière Gro-Lux, les limbes qui contiennent davantage de glucides sont toujours moins développés.Effects of two illumination sources on growth and on carbohydrate and gibberellin leaf contents of in vitro grown Cichorium intybus L. Fourteen-d old seedlings of Cichorium intybus L (cv Flash) were grown in vitro under a 16-h photoperiod (15 ± 1 W m-2 ). Two different spectral emissions (fig 1) were obtained by using Cool-White and Gro-Lux fluorescent lamps. Differences in the growth (table I), of gibberellin (fig 2) and carbohydrate (table II) contents of leaves were observed. Plantlets grown under Cool-White lamps developed larger leaves with a high level of gibberellin-like activity. Carbohydrate content increased in the Gro-Lux illuminated leaves

Pretreatments, conditioned medium and co-culture increase the incidence of somatic embryogenesis of different Cichorium species

Somatic embryogenesis (SE) in Cichorium involves dedifferentiation and redifferentiation of single cells and can be induced by specific in vitro culture conditions. We have tested the effect of various treatments on the incidence of SE (ISE) of an interspecific embryogenic hybrid (C. endivia x C. intybus) and of different commercial chicories (C. endivia and C. intybus) that are typically recalcitrant to SE in standard culture conditions. We found that the ISE of the hybrid is significantly increased by pretreatment of tissues by submersion in solutions of glycerol, abscisic acid, spermine, putrescine or of combinations of these compounds. Interestingly, the most efficient of these pretreatments also had an unexpectedly high effect on the ISE of the C. intybus cultivars. The ISE of the hybrid and of the commercial chicories were increased when explants were co-cultured with highly embryogenic chicory explants or when they were cultured in conditioned medium. These observations established that unidentified SE-promoting factors are released in the culture medium. HPLC analyses of secreted Arabino-Galactan Proteins (AGPs), which are known to stimulate SE, did not allow identifying a fraction containing differentially abundant AGP candidates. However, pointing to their role in promoting SE, we found that the hybrid had a drastically higher ISE when amino sugars and L-Proline, the putative precursors of secreted AGPs, were both added to the medium