Organogènesi adventícia i nivells dàcid indol-3-acètic i citocinines endògens en explants de pètals i fulles de clavell ("Dianthus" L.) cultivats "in vitro".

En aquesta tesi sha estudiat el proces dorganogenesi adventicia de brots i rels en el clavell. Duna banda sha demostrat lefecte de genotip en aquest proces, tot sent el cultivar White Sim el mes regeneratiu. Previament shavien estudiat les relacions genetiques entre els vuit cultivars de clavell estudiats, mitjancant analisis RAPDs. Tambe sha trobat un efecte de lexplant en aquest proces morfogenic, tot sent les fulles lleugerament mes regeneratives que els petals. I tambe un efecte del tipus, balanc i concentracio dels reguladors del creixement exogens (lauxina NAA i les citocinines BA i TDZ). Cal destacar el gran efecte morfogenic del thidiazuron (TDZ), comparat amb la benziladenina (BA), i la sinergia trobada entre el TDZ i lacid naftalenacetic (NAA) en la regeneracio de brots. El TDZ ha tingut un efecte organogenic tant directe, com indirecte a traves de promoure un increment en determinades citocinines endogenes. Aquestes shan trobat localitzades (mitjancant la tecnica de la immunolocalitzacio) en els meristemes apicals dels primordis caulinars adventicis en formacio. La concentracio dagar del medi i la humitat relativa del cultiu han influit tambe en la capacitat organogenica dels explants estudiats i en el grau dhiperhidricitat dels brots regenerats. La presencia del gen rolC d"Agrobacterium rhizogenes" en plantes de clavell ha incrementat la capacitat organogenica, tant de brots com de rels, dels explants de clavell, mostrant un efecte similar al de les citocinines i al de les auxines, respectivament. Quantificacions de citocinines endogenes en les diferents linies estudiades han demostrat que les fulles transgeniques presenten nivells mes elevats de citocinines tipus zeatina que les fulles control, mentre que els petals transgenics tenen mes concentracio de citocinines tipus isopenteniladenina (iP). La concentracio diP ens els petals de les diferents linies transgeniques estudiades sha correlacionat amb la capacitat de regeneracio dels petals. Daltra banda, donat que els nivells dauxines de les plantes "rolC" son similars als de les plantes no transgeniques, lefecte dauxina del gen "rolC" sexplicaria per un increment de la sensibilitat a las auxines. Finalment, lestudi de la influencia dels gens "rol" d"Agrobacterium rhizogenes" en plantes ornamentals amb flor ha mostrat que el fenotip obtingut pot ser de gran interes comercial, donat que promouen habits de creixement compactes, una major ramificacio lateral, millor arrelament i un increment en la floracio, la qual, en alguns casos, pot fins i tot avancar-se. La disminucio de la fertilitat masculina, obtinguda en la major part de transformacions, seria practicament lunica caracteristica negativa. Dentre els gens "rol", el "rolC" seria el mes recomanable, donat que els seus efectes son els mes avantatjosos pel que fa a la millora de trets ornamentals i horticulturals. "ENGLISH ABSTRACT: In this thesis we have studied the adventitious organogenesis of shoots and roots in carnation. On one hand, we have found an effect of the genotype in this process, the White Sim cultivar being the most regenerative among the studied cultivars. Previously, we analyzed the genetic relatedness among the eight carnation cultivars. We have also found an effect of the explant in this morphogenic process: leaves were found to be more regenerative than petals. And finally, we have shown an effect of the type, balance and concentration of exogenous plant growth regulators (auxins and cytokinins). It is worth noting the great morphogenic effect of thidiazuron (TDZ), compared with benzyladenine, and the synergy found with TDZ acting together with naphthaleneacetic acid in the adventitious shoot regeneration. TDZ showed a direct effect on the shoot organogenesis, but also an indirect effect by promoting an increase in specific endogenous cytokinins. The cytokinins have been located in the apical meristems of the adventitious shoot primordia formed on the petal surface. The agar concentration of the media and the relative humidity of the culture atmosphere have also influenced the organogenic capacity of the studied explants and the hyperhydricity of the regenerated shoots. The introduction of the rolC gene of Agrobacterium rhizogenes in carnation plants have improved both shoot and root organogenesis of the explants, thus showing a cytokinin-like but also an auxin-like activity. By quantifying the endogenous cytokinins, rolC-transgenic leaves have been found to have higher levels of zeatin-type cytokinins, whereas rolC-transgenic petals have shown higher levels of isopentenyladenine-type cytokinins. On the other hand, since auxin levels of rolC-transgenic plants have not differed from those of non-transgenic plants, the auxin-like effect of the rolC gene could be explained by an increase in auxin sensitivity in transgenic tissues. Finally, the study of the influence of rol genes in floriculture have shown that the obtained phenotype by transforming ornamental flowering plants with rol genes can be commercially desirable, since these genes promote dwarf and bushy phenotypes, promote better rooting and improve flowering, both by increasing the number of flowers and advancing the flowering time. Among rol genes, the rolC gene is the most recommendable. "