Integrating traditional breeding with modern biotechnology: Innovative practices in the construction of second-generation breeding populations of Korean pine

The primary aim of this study was to shorten the traditionally 25- to 50-year breeding cycle of Pinus koraiensis through molecular marker-assisted early selection and establish a second-generation breeding population, thereby providing a theoretical foundation and elite germplasm resources for advanced-generation breeding research on Korean pine. Preliminary family selection was conducted on the basis of the diameter at breast height (DBH) of 117 Korean pine open-pollinated families in Weihe Forest Enterprise of Heilongjiang Province, China. Between September and December 2024, this study conducted a comprehensive evaluation of breeding materials by integrating acoustic velocity with Kompetitive Allele Specific PCR (KASP) marker genotyping associated with economically significant traits. A combination of SSR markers and conifer traits was employed to analyse genetic diversity and construct the breeding population. A total of 477 plus trees were selected for incorporation into the breeding population. A total of 14.32 % of the molecular variation was observed among families, and the progeny exhibited excessive heterozygosity. A total of 259 individuals with homozygous mutant genotypes for both markers Pk3270935 and Pk1780727 were selected as an elite fruiting population. Furthermore, 206 individuals were selected in their entirety to constitute an elite wood property population. On the basis of these two elite populations, a breeding population for excellent fruiting (Pop1) and a breeding population for superior wood properties (Pop2) were established according to genetic and phenotypic diversity, consisting of 127 and 110 individuals respectively. The breeding populations display considerable genetic diversity while maintaining the original phenotypic variation. The combination of family and individual selection in the construction of the second-generation Korean pine breeding population allows for the effective balancing of genetic gain and genetic diversity. The implementation of KASP genotyping and wood properties in the screening of breeding materials has the potential to significantly increase breeding efficiency and achieve precision breeding. This, in turn, provides a foundation for the planned implementation of high-generation hybrid breeding in Korean pine. • Molecular marker-assisted early selection in Korean pine drastically shortens the traditional 25–50 year breeding cycle. • Built a 2nd-generation breeding population by integrating phenotype and KASP marker genotyping. • Formed two elite sub-populations: 259-tree elite fruiting population (homozygous at key markers) and a 206-tree wood‑trait group. • Developed diverse breeding populations for high fruiting (127 trees) and superior wood (110 trees), balancing genetic gain and diversity. • KASP genotyping combined with wood traits boosts breeding efficiency and enables precision breeding for advanced-generation hybrids.