Publications des agents du Cirad


Citrus germplasm exploitation by somatic hybridization

Ollitrault P., Dambier D., Lotfy S., Rist D., Mas O., Luro F., Froelicher Y.. 2000. In : International Society of Citriculture. 9th ISC Congress, 3-7 December 2000, Orlando (Etats-Unis). s.l. : s.n., p. 122-122. Congress of the International Society of Citriculture. 9, 2000-12-03/2000-12-07, Orlando (Etats-Unis).

Somatic hybridization is a means of increasing genetic variability of several crops gene pool. not only by overcoming sexual incompatibility between species, but also by combining nuclear, chloroplastic, and milochondrial genomes in new patterns. It appears particularly adapted for citrus regarding the constraint of ils breeding system and the genetic structure of the gene pool. This poster present the major applications of somatic hybridization in citrus on the basis of Cirad and Inra works. Somatic hybridization is done by electrofusion of proloplasts. The regenerated plantlets are characterised by flow cytometry, isozyme analysis, and CAPS cytoplasmic markers Io assess, respectively, the ploidy level and the nuclear and cytoplasmic origins. Somatic hybridization allows the exploitation of polyembryonic (apomictic) and sterile cultivars for the diversification of the tetraploid gene pool. The tetraploid hybrids, that we have obtained for 20 combinations, will be used for further sexual crosses with diploid to create seedless triploid cultivars. Direct triploid synthesis by somatic hybridization between diploid cultivars and haploid lines is also mastered and several hundred tetraploid and triploid plants are in field evaluation under tropical and Mediterranean conditions. The total addition of the genes of the two parents, irrespective to their heterozygosity, finds important applications for rootstock breeding. An intergeneric hybrid (P. trifoliata + C. deliciosa) is very promising for the constraints of the Mediterranean Basin. Alloplasmic plants have been obtained and pave the way for the study of the interaction between nuclear and cytoplasmic genomes.
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