RÉSUMÉ
Embryogenic cell suspension cultures of garlic (Allium sativum L.) were initiated in liquid medium from friable embryogenic tissue. The optimal parameters for culture maintenance were: (1) an initial cell density of 1-4% (v/v); (2) medium renewal every 14 days and subculturing every 28 days; (3) a low 2,4-dichlorophenoxyacetic acid concentration (0.1-0.3 mg/l). Cultures regenerated during a 14-month period. The cell suspension cultures differentiated embryos following transfer to a semi-solid embryo induction medium, with histological studies confirming and characterising the embryogenic nature of the process. Forty percent of these embryos converted into plantlets, which produced micro bulbs in vitro. The composition of the sulphur compounds of the micro bulbs obtained from cell suspension embryo-derived plantlets differed slightly from those produced by in vitro shoot proliferation-derived plantlets, but after two cycles of multiplication in the field these differences had disappeared.
Sujet(s)
Développement embryonnaire/physiologie , Ail/embryologie , Ail/croissance et développement , Régénération/physiologie , Graines/métabolisme , Acide 2,4-dichlorophénoxy-acétique/pharmacologie , Techniques de culture cellulaire/méthodes , Techniques de culture cellulaire/normes , Différenciation cellulaire/physiologie , Cellules cultivées , Ail/métabolisme , Pousses de plante/croissance et développement , Pousses de plante/métabolisme , Graines/composition chimique , Composés du soufre/analyse , Composés du soufre/métabolismeRÉSUMÉ
Summary Cassava clones traditionally cultivated in Africa, frequentty show some degenerating signs ("African Cassava mosaic"). Refering to an healthy clone from VietNam, the distribution, transmission and progression of the causal agent have been observed from cutting and graft experiments. In vitro culture enable us to adjust thermotherapy treatments leading to the cure of all the studied clones and to obtain an accelarated vegetative multiplication leading to the rapid reconstitution of healthy clones.
Resumo Os clones africanos da mandioca cultivados tradicionalmente na África, apresentam freqüentemente certos sintomas de degenerescência (African Cassava mosaic). A repartição, a transmissão e a progressão do agente patogênico, foram estudadas a partir de experiências feitas através de transplantações ou enxertos, guardando como referência do clone indene de sintomas, proveniente do Vietnã. A cultura in vitro permitiu o aperfeiçoamento dos tratamentos de termoterapia conduzindo à cura de todos os clones estudados, e à obtenção de uma multiplicação vegetativa acelerada, que permite a reconstituição de clones saudáveis em pouco-tempo.
