Establishment of regeneration system of Pyrus and the genetic stability analysis of regenerated population

Genetic assessment of pear regeneration population is very important for genetic fidelity maintenance in genetic engineering breeding. In this research, a regeneration system for a pear dwarfing rootstock cultivar, ‘Qingzhen D1’, was established using NN69 medium supplemented with different concentrations of thidiazuron (TDZ) and indole-3-butyric acid (IBA). The genetic stability of the regenerated population was evaluated through flow cytometry (FCM) and whole genome resequencing techniques. The highest regeneration rate (93%) was induced on NN69 medium supplemented with 3.0mg·L − 1 TDZ and 2.4mg·L − 1 IBA, with 3.9 adventitious buds per leaf. No phenotypes and ploidy changes were detected in regeneration population. But a high variation frequency (5.0 × 10 − 4 ) at a single site was detected. The mutations occurred most frequently on chromosome 5, 10 and 15, while least 4. High-impact changes only accounted for 0.065% of single-nucleotide polymorphism (SNPs) and 1.429% of insertions or deletions of nucleotides from a sequence (Indels) of all polymorphisms, most of which caused by frameshift. Functional analysis of genes affected by high-impact variants showed that they were mainly related to adaptation to environment. This study will provide a theoretical basis for the application of pear genetic engineering breeding in the future.