Genetic Improvement of Pinus koraiensis in China: Current Situation and Future Prospects

Pinus koraiensis (Sieb.et Zucc) is an economically and ecologically important tree species, naturally distributed in northeastern China. Conservation efforts and genetic improvement for this species began in the 1960s and 1980s, with the establishment of several primary seed orchards based on range-wide provenance evaluations. The original breeding objective was to improve growth and wood yield, but during the recent decade, it was redefined to include other traits, such as an enhancement of wood properties, seed oil content, cone yield, and the development of elite provenance with families, clones, and varieties with good tolerance to biotic and abiotic stresses. However, improvement processes are slow due to a long breeding cycle, and the number of improved varieties is still low. In this review, we summarize the recent progress in the selective improvement of P. koraiensis varieties, such as elite provenance, family, and clones, using various breeding procedures. We collate information on advances in the improvement of P. koraiensis, based on conventional breeding and molecular marker-assisted breeding methods; identify gaps in our understanding of the tree improvement processes; and propose future research directions, which will provide new insight for subsequent genetic breeding research on P. koraiensis.