Résumé
Diploid Citrus x Poncirus rootstock are used by the citrus industry worldwide. A new generation of promising allotetraploid rootstocks has also been developed. The rate of nucellar/zygotic plants among seedlings is a key trait for the production of genetically conform trees by seedlings. Isozymes and SSRs have been successfully used for the detection of zygotic plants in diploid seedlings but their application in heterozygous tetraploids in more difficult. We have developed new nuclear SNPs markers (KASParTM technology) phylogenetically diagnostic of the Poncirus genus (DSNPs) and therefore heterozygous for all intergeneric hybrids for first generation. DSNPs were mined from Sanger Sequencing of candidate genes for abiotic stress tolerances and additional gene sequences providing a coverage of the 9 citrus chromosomes. 23 DSNPs were successfully developed. These markers were efficient for allele doses estimation in polyploids. We applied them to identify zygotic plants in seedlings of diploid and doubled diploid Carrizo citrange, 4475 citrumelo, Cleopatra x Poncirus citrandarin and of the tetraploid somatic hybrid FLHORAG1. The rates of zygotic plants were relatively low (<6%) for mots rootstocks excepted the tetraploid citrumelo 4475 (29%). This high zygotic rate should preclude, the propagation of citrumelo 4475 tetraploid by seeds. (Texte intégral)