Publications des agents du Cirad


Biotechnology for triploid mandarin breeding

Ollitrault P., Dambier D., Sudahono, Mademba-Sy F., Vanel F., Luro F., Aubert B.. 1999. In : Aubert B. (ed.). 5th world congress of the International Society of Citrus Nurserymen. Proceedings of the congress = [Cinquième congrès mondial de la Société Internationale des Pépiniéristes d'Agrumes. Actes du congrès]. Montpellier : CIRAD, p. 337-337. World Congress of the International Society of Citrus Nurserymen. 5, 1997-03-05/1997-03-08, Montpellier (France).

Introduction. As seedlessness is a major criteria for the citrus fresh fruit market, breeding triploid individuals appears promising. Three strategies are currently under development by Cirad-Flhor and Inra (France) for triploid citrus breeding with the support of biotechnology. Materials and methods. Spontaneous triploids were researched in clementin zygotic embryos collected in mature fruit small seeds (strategy 1). Somatic hybridization was used either to obtain allotetraploids for subsequent hybridization with diploids (strategy 2) or, directly, for haploid and diploid protoplast fusion (strategy 3). Regenerated plants, embryos or calli were studied by flow cytometry and by isozyme analysis to assess their ploidy level and the origins of their nuclear genomes. Results and discussion : ¿ a total of 85 triploid hybrids is currently propagated in greenhouse for further evaluation under mediterranean and tropical conditions. As several mechanisms appear to be at the origin of triploid progenies, additional molecular marker studies are necessary to correctly assess the rules of the spontaneous triploid formation in citrus; ¿ tetraploid somatic hybrids were selected from 16 intraspecific, interspecific and intergeneric combinations.They will be used for pollination of diploid monoembryonic mandarins and should generate heterozygous and polymorphic triploid progenies; ¿ somatic hybridization between haploid and diploid protoplasts was achieved with a haploid embryogenic callus line of clementine and several diploid callus lines or mesophyll protoplasts. Conclusion. A proper choice between these strategies, according to specific objectives and heterozygosity of diploid genitors, will result in large triploid populations with a high potential for the selection of new easy peeler seedless citrus cultivars.

Mots-clés : citrus; biotechnologie végétale; sélection; variété apyrène; fusion de protoplastes; hybridation somatique; tétraploïdie; triploïdie; diploïdie

Communication de congrès

Agents Cirad, auteurs de cette publication :