A comprehensive evaluation of 515 Korean wheat germplasms, including cultivars, experimental lines, and landraces, was conducted over 2 years under upland field conditions to characterize major agronomic and grain traits. Allelic variation at 13 key functional loci was assessed using Kompetitive Allele-Specific PCR (KASP) and PCR-based markers. The winter-type vrn-A1 with a single copy (CNV=1; 40.2%) advanced heading by approximately 5 days compared to multiple-copy genotypes, and winter-type vrn-B1 (88.5%) advanced heading by 2 days compared to the spring-type. The photoperiod-insensitive alleles Ppd-B1a (5.6%) and Ppd-D1a (76.3%) advanced heading by 3 and 4 days, respectively, with a combined effect of up to 6 days. Semi-dwarfing alleles Rht-B1b and Rht-D1b showed reduced culm lengths of 2.1 cm and 4.7 cm, respectively, and the Rht-B1a/Rht-D1b genotype was 6 cm shorter than Rht-B1a/Rht-D1a. The Pina-D1a/Pinb-D1a genotype had the lowest kernel hardness value (32.2), whereas Pina-D1b/Pinb-D1a had the highest (60.5). The thousand kernel weight ranged from 36.1 mg to 42.5 mg depending on the allelic combinations of TaCwi-A1, TaGW2-6A, and TaSus2-2B. Cultivars and experimental lines were clearly distinguished from landraces based on phenotype-based clustering, with the majority of cultivars (81.6%) and experimental lines (68.3%) grouped into cluster III. In contrast, landraces were predominantly distributed in clusters I (55.1%) and II (29.2%). Random forest analysis identified four genes, Ppd-D1, Pina-D1, Pinb-D1, and WAPO-A1, as major contributors to cluster classification. Cluster III was highly enriched with alleles favorable for earliness (Ppd-D1a, 98.3%) and grain hardness (Pina-D1b and Pinb-D1b, 57.9%). WAPO-A1b, an allele associated with an increased spikelet number per spike, was more frequently observed in clusters I (94.6%) and II (79.1%) than in cluster III (58.4%).

Studies on forest tree breeding (FTB) in South Korea started in the 1950s and have achieved remarkable outcomes through various techniques and methods such as selective breeding, cross breeding, introduction breeding, and biotechnology. Despite these outstanding achievements, no attempt has been made to
objective
ly and quantitatively evaluate the results of domestic FTB research. Here, we quantitatively analyzed past research trends using keywords of published journal papers and compared the current domestic research level of FTB with the international level. Using various keywords in this field, we searched for research articles published in the Journal of Korean Society of Forest Science, the Korean Journal of Breeding Science, and the journals listed on the Science Citation Index from 1962 to present. The analysis of these studies showed that the research on FTB has grown quantitatively in Korea, and has been conducted on various subjects. Research topics from Korea, in terms of purpose and species, are not significantly different from those of foreign countries. The genus Pinus has been the major subject of FTB studies both domestically and internationally. However, in foreign FTB research, the trees used for research have diversified each year, while they were not diverse in Korea. The FTB research capacity of Korean national institutions, such as the National Institute of Forest Science, continues to dramatically increase, while the research capacity of universities is relatively low. Based on the results of this analysis, it is necessary to establish a concrete and effective policy for future research and development of FTB.

Forest tree improvement is relatively a young science and its purpose is to provide guidance for the conservation, management and sustainable utilization of genetic resources of natural and managed forests. In South Korea, forest tree improvement programs started in 1956. The programs had two main aims: to guarantee the genetic origin of the forest reproductive materials used in afforestation and reforestation, and to develop genetically improved individuals and varieties of some commercially important trees. Since the launch of the forest tree improvement programs, biomass production has been the major improvement target, together with overall adaptability to different sites. Further improvement targets have recently been added, including wood quality traits, and more specific targets linked to adaptation to abiotic and biotic factors in response to new socioeconomic needs and global changes. Additionally, since the early 1970s, forest genetic resource conservation and forest fruit and nut tree breeding have progressed in South Korea. Molecular breeding techniques based on omics information are being developed to enhance the efficacy of selection and to accelerate forest tree breeding cycles. Genetic engineering, including gene editing, has also been applied, but is currently limited to research purposes. Forest tree improvement will be an integral part of the bioeconomy in securing the production of good quality raw materials in large quantities, and will play a significant role in sequestering carbon dioxide and decelerating climate change in the long term.