Molecular identification of F1 hybrids of Fraxinus mandshurica × Fraxinus chinensis using SSR markers

Abstract

To breed new Fraxinus varieties with superior traits including rapid growth, drought tolerance, and salinity resistance, this study established 480 F₁ interspecific hybrid progeny through controlled pollination, using Fraxinus mandshurica Rupr. as the female parent and Fraxinus chinensis Roxb. as the male parent. Early-stage hybrid identification was performed using SSR (simple sequence repeat) markers. From 37 candidate SSR primers, two highly polymorphic pairs were selected for hybrid verification via polyacrylamide gel electrophoresis. Of the 480 offspring, 280 were confirmed as true hybrids, yielding a hybrid purity of 58.33 %. Primer pair Fm19 detected 62.29 % of hybrids, with partial overlap (shared detection) with primer pair Fc1. The polymorphism information content (PIC) ranged from 0.93 to 0.97 (mean: 0.95). Polymorphic alleles from both primers were converted into binary data (1 = present, 0 = absent) to generate unique molecular IDs for 144 hybrid offspring. This work established an efficient SSR-based method for early hybrid identification in F. mandshurica and F. chinensis, facilitating accelerated breeding and variety development.