Study on the biological effects of low-energy nitrogen ions implantation on Platycodon grandiflorusm seeds

In order to study the effects of low-energy nitrogen ions injection on the Platycodon grandiflorus seed, the Platycodon grandiflorus seeds were treated by the Nitrogen ion beam with six doses, 2, 4, 6, 8, 10, 12 × 10¹⁶N⁺ · cm^-2 respectively at 25 KeV and 35 KeV. The optimal treatment condition was explored by measuring the survival rate of M₀ generation, and the morphological characteristics were analyzed to select elite mutants. Furthermore, the ISSR molecular markers were employed to analysis the poly morphic loci of the mutant plants. The results showed that the highest survival rate was 77% with the treatment of 12 × 10¹⁶N⁺ · cm^-2 at 25 KeV. In addition, phenotypes changes of the mutants include the flower type, flowering phase, and plant height were obseved, which like the sepal changed into petal, the delayed flowering phase and the shorter plants height. The ISSR analysis showed that 250 loci were amplified in total with 20 pairs of primers, among which 87 loci were polymorphism. The polymorphic rate was 34.80% and 4.35 polymorphism loci in average per pair of primers averagely. This study provides a reference for the mutation breeding of Platycodon grandiflorus by using N⁺ injection. (authors)