EFFICIENT HAPLOID PRODUCTION ON 'WILKING' MANDARIN BY INDUCED GYNOGENESIS

Seedlessness is a major criterion for the citrus fresh fruit market. Therefore, triploidy breeding appears very promising for the selection of new citrus cultivars. CIRAD has developed a method to produce triploid hybrids by somatic hybridization between diploid and haploid lines and demonstrate the potential for haploid citrus production by induced gynogenesis in clementine. In this work we analyzed the efficiency of induced gynogenesis by irradiated pollen in ‘Wilking’ mandarin (Citrus reticulate). Four doses of gamma irradiation of ‘Meyer’ lemon pollen were tested (150, 200, 250, 300 Grays). Embryos were extracted from small seeds, obtained in immature fruits, and cultivated in vitro. The ploidy level of plantlets was determined by flow cytometry analysis. Irradiated pollen appeared to be efficient for gynogenesis induction in ‘Wilking’. A relatively high number of haploids (7 plantlets) was obtained, essentially after hybridisation with pollen irradiated at 250 Grays. The ploidy level of all haploid plantlets was confirmed by chromosome count. These haploid lines should be useful for triploid breeding by somatic hybridisation and also constitute interesting resources for genomic studies.