AFLP Analysis of Mutations Induced by Gamma Irradiation in 'Rojo Brillante' Persimmon

In the Mediterranean area, the production of persimmon (Diospyros kaki Thunb.) [2n=6x=90] has increased recently as an alternative to the major fruit crops. In Spain, production relies almost exclusively on the 'Rojo Brillante' which accounts for 83% of the crop. Monovarietal culture implies several commercial and phytosanitary problems that can compromise the future of the crop. Main persimmon breeding objectives are focused on obtaining new cultivars with the positive agronomic features of 'Rojo Brillante' but with more diversity in ripening date, astringency and fruit characteristics. In order to increase the genetic variability available for breeding, the strategy of mutagenesis with.-radiation was employed. Shoot buds of the persimmon 'Rojo Brillante' were subjected to various doses of gamma rays, 15 and 20 Gy from a Co-60 source (treatment A) and 20 and 25 Gy with a linear accelerator (treatment B). The genetic variability induced was analyzed in 420 plants using four AFLP primer combinations. Irradiated buds were grafted in the field and bud sprout rate appreciably decreased with the increase of the dose. The most favorable gamma irradiation dose combining survival and mutation induction was 20 Gy. AFLP data analyses revealed high genetic variability produced by 20 Gy: treatment A resulted in 29.8% of polymorphic loci (PPL) and treatment B resulted in 45.8% of PPL.