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Background The Auxin Responsive Factor ( ARF ) family plays a crucial role in mediating auxin signal transduction and is vital for plant growth and development. However, the function of ARF genes in Korean pine ( Pinus koraiensis ), a conifer species of significant economic value, remains unclear. Results This study utilized the whole genome of Korean pine to conduct bioinformatics analysis, resulting in the identification of 13 ARF genes. A phylogenetic analysis revealed that these 13 PkorARF genes can be classified into 4 subfamilies, indicating the presence of conserved structural characteristics within each subfamily. Protein interaction prediction indicated that Pkor01G00962.1 and Pkor07G00704.1 may have a significant role in regulating plant growth and development as core components of the PkorARFs family. Additionally, the analysis of RNA-seq and RT-qPCR expression patterns suggested that PkorARF genes play a crucial role in the development process of Korean pine. Conclusion Pkor01G00962.1 and Pkor07G00704.1 , which are core genes of the PkorARFs family, play a potentially crucial role in regulating the fertilization and developmental process of Korean pine. This study provides a valuable reference for investigating the molecular mechanism of embryonic development in Korean pine and establishes a foundation for cultivating high-quality Korean pine.

Background GATA transcription factors, a type of zinc-finger DNA-binding protein, play a crucial role in regulating various biological processes including plant growth, stress response, and hormone signaling by controlling the expression of target genes. Recently, GATA genes have been discovered in numerous plant species. However, they have not yet been reported in Korean pine ( Pinus koraiensis ). Results In this study, a total of 15 PkorGATA genes were identified in the whole genome of Korean pine. These PkorGATA genes are unevenly distributed across nine chromosomes and are categorized into four subfamilies based on their conserved structural domains. The results of cis-acting element analysis, RNA-seq, and qRT-PCR indicate that PkorGATA genes play a significant role in the developmental processes of Korean pine ovules. Moreover, subcellular localization results revealed that PkorGATA2 , PkorGATA3 , PkorGATA8 , PkorGATA9 , PkorGATA10 and PkorGATA11 are localized in the nucleus. The transcriptional activation activity of six PkorGATA proteins in yeast showed that PkorGATA2, PkorGATA3, and PkorGATA10 exhibit transcriptional activation capabilities, suggesting that their potential function as transcription factors within the nucleus. Conclusion In general, this study provides candidate gene resources for functional exploration of GATA genes.

Branch growth is an important aspect of the tree growth process. Studying the branch growth pattern is important for understanding the growth of trees and optimizing forest management decisions. A total of 48 planted Korean pine sample trees from northeast China were selected, and a total of 327 sample branches were measured for branch diameter growth model development and 323 sample branches for branch length. Based on the aforementioned research objectives and the obtained data, the impact of individual tree variables, branch variables, and forest stand competition variables on branch growth were initially investigated in this study. Finally, we constructed nonlinear mixed-effects models at the individual tree level. The results show that the Mitscherlich growth equation had the best fitting accuracy and was selected as the base model for developing the Korean pine branch growth model. Forest stand competition of the ratio of the basal area of the subject tree to the mean basal area of the stand (CI2) and branch variables of the branch length and branch diameter had the most significant contributions and were selected and introduced into the branch growth models. The branch growth became larger with increasing CI2, branch length and branch diameter, but the effects of the branch height and diameter at the breast height on branch growth should be considered in combination with their parameters and other variables together. In addition, the introduction of random effects effectively improves the fitting accuracy of the branch growth model. Overall, the Korean pine branch growth models developed in this study have good fitting performance and have important theoretical and practical value.

As a significant fruit and timber tree species among conifers, Pinus koraiensis remains it evergreen status throughout the harsh winters of the north, a testament to its intricate and prolonged evolutionary adaptation. This study delves into the annual trends of physiological indicators, gene expression levels, and metabolite accumulation to dissect the seasonal adaptability of P. koraiensis needles. Chlorophyll content reaches its zenith primarily between July and September, whereas carotenoids persist until spring. Additionally, notable seasonal variations are observed in the levels of soluble sugar and protein. Transcriptome data is categorized into four distinct stages: spring (S2), summer (S3-S4), autumn (S5), and winter (S6-S1). The differential expression of transcription factor genes, including bHLH, MYB-related, AP2/ERF, C3H, and NAC, provides insights into the needles’ seasonal adaptations. Analysis of chlorophyll and carotenoid metabolism, sugar metabolism, and the MAPK signaling pathway identifies PSY5 (Cluster-50735.3), AMY13 (Cluster-37114.0), pgm1 (Cluster-46022.0), and MEKK1-1 (Cluster-33069.0) may as potential key genes involved in sustaining the needle’s evergreen nature and cold resistance. Ultimately, a comprehensive annual adaptability map for P. koraiensis is proposed, enhancing understanding of its responses to seasonal variations.

Korean pine broadleaf mixed forest is an important ecosystem for maintaining biodiversity in Northeast China. Korean pine is also an important species for the production of timber and nuts in the mountainous areas of Northeast China. In this study, we compared three types of Korean pine callus and found that embryogenic callus had high amounts of storage substances (protein, sugar and starch). Non-embryonic callus had high levels of polyphenols and polyphenol oxidation, while callus that lost somatic embryogenesis potential had lower levels of storage substances (protein, sugar and starch) and higher contents of peroxidase and catalase. These results indicate that high contents of storage substances (protein, sugar and starch), and low levels of polyphenols and polyphenol oxidase can be used as physiological markers of callus with somatic embryogenic potential. During the development process of Korean pine somatic embryos, fresh weight and dry weight gradually increased, while water content gradually decreased. Soluble protein, starch, soluble sugar and superoxide dismutase also increased during development, while peroxidase and catalase levels reduced over time. These results indicate that somatic embryogenesis involves energy storage, and antioxidant enzymes cooperate to regulate the occurrence and development of embryos. These results provide physiological markers for identification of embryogenic callus with somatic embryogenesis, to evaluate callus suitable for somatic embryogenesis, and provide basis for further research on the molecular mechanisms of somatic embryogenesis.

Abstract Understanding the natural regeneration of Korean pine (Pinus koraiensis Sieb. et Zucc.) in mixed broadleaved–Korean pine (MBK) forests is crucial for MBK forest conservation and secondary deciduous broadleaved forest restoration. We hypothesized the ratio of Korean pine basal area (RKp) in MBK stands affected its natural regeneration. Regeneration censuses, including the height, root collar diameter, age, and growth stages (younger seedling, older seedling, smaller sapling, and taller sapling) of Korean pine, were conducted in northeast China. Results indicated the stem density and age composition of younger seedlings were positively correlated with RKp, whereas those of the saplings were negatively correlated with RKp. In the stands with lower RKp (<80% in Lesser Khingan Mountains [LKM]; <40% in Lushuihe Forestry Bureau [LFB]), individuals in all growth stages regenerated well with an age span of 65 yr. However, the regeneration of taller saplings was severely inhibited with increasing RKp (LKM: RKp ≥ 80%; LFB: RKp ≥ 40%). In summary, RKp significantly affected the natural regeneration of Korean pine in MBK forests. The basal-area thresholds limiting regeneration were found to be 80% in LKM stands and 40% in LFB stands. These basal-area thresholds provided evidence of why the zonal climax was MBK forests rather than pure Korean pine forests.

Korean pine (Pinus koraiensis Sieb. et Zucc.) is the most important forest vegetation in northeast China. The timber quality of this tree species is largely driven by branch growth and distribution within the crown. Thus, developing branch diameter and length models, especially those that include competition indices, is essential. A total of 48 Korean pine trees were selected to conduct destructive measurements of branch characteristics. This was carried out on all live branches, and a branch diameter and length model was developed. Various indices, including the absolute depth into the branch base (DINC) from tree tip, were used. The equation with the largest Radj2 and smallest root mean square error (RMSE) values was selected as the best model. Each parameter from the best model was reparameterized to the tree variables and competition indices. Finally, the branch diameter model that included diameter at the breast height (DBH), tree height (HT), and the crown length index (CLI), and the branch length model that included DBH and HT exhibited the best performance. The Radj2 and RMSE values were 0.42 and 4 mm, respectively, for the branch diameter model, and 0.77 and 63 cm, respectively, for the branch length model. Branch diameter and length increased as DBH increased and decreased as HT increased. Furthermore, branch diameter decreased as the CLI increased.

The water retention capacity of forest leaf litter was estimated through lysimeter measurements under field conditions. Six lysimeters were placed in Pinus koraiensis and Quercus acutissima forests and filled with the surrounding leaf litter to represent the effects of litter type on the water retention capacity. Two years of measurements for rainfall and litter weight have been conducted in all lysimeters at 30 min intervals. Field measurements showed that P. koraiensis litter stored more water during rainfall periods than did Q. acutissima litter. As a result, immediately after the cessation of rainfall, 1.82 mm and 3.00 mm of water were retained per unit mass of Q. acutissima and P. koraiensis litter, respectively. Following rainfall, after the gravitational flow had entirely drained, the remaining water adhered to the litter was estimated to be 1.66 ± 1.72 mm and 2.72 ± 2.82 mm per unit mass per rainfall event for Q. acutissima and P. koraiensis litter, respectively. During the study period, approximately 83.7% of incident rainfall drained into the uppermost soil layer below the Q. acutissima litter, whereas 84.5% of rainfall percolated through the P. koraiensis litter. The moisture depletion curves indicated that 50% of the water retained in the Q. acutissima and P. koraiensis litter was lost via evaporation within 27 h and 90 h after the cessation of rainfall, respectively. This study demonstrated the water retention storage of leaf litter and its contribution to the water balance over floor litter according to litter and rainfall characteristics. The results also proved that lysimetry is a reliable method to quantify the variation of litter moisture under natural conditions.

Studying the genetic diversity and population structure of natural forest populations is essential for evaluating their ability to survive under future environmental changes and establishing conservation strategies. Pinus koraiensis is a conifer species with high ecological and economic value in Northeast China. However, its natural forests have been greatly reduced in recent years, mostly due to over exploitation and over utilization. Here, we evaluated the genetic diversity and population structure of seven populations of P. koraiensis located throughout its native distribution. A total of 204 samples were genotyped with nine polymorphic nuclear SSR (simple sequence repeat) markers. The results showed high genetic diversity in all populations, with an average expected heterozygosity of 0.610, and the northern-most populations (Dailin (DL) and Fenglin (FL)) showed slightly higher diversity than the other five populations. The level of genetic differentiation among populations was very low (FST = 0.020). Analysis of molecular variance (AMOVA) showed that only 2.35% of the genetic variation existed among populations. Moreover, STRUCTURE analysis clearly separated the seven populations into two clusters. Populations DL and FL from the Xiaoxinganling Mountains comprised cluster I, while cluster II included the five populations from the Changbai Mountains and adjacent highlands. Our research on the genetic diversity and population structure of P. koraiensis in natural forests of China can provide a basis for the implementation of programs for the conservation and utilization of P. koraiensis genetic resources in the future.

, as a keystone tree species, possesses immense economic and ecological value. However, the present cultivation of high-quality seedlings in plantations remains hindered by prohibitively high costs and inadequate technological advancements. Additionally, the species' prolonged growth cycle and low yield, when compounded by issues such as excessive harvesting, may result in supply constraints. Plant growth regulators (PGRs), a class of naturally occurring or synthetically derived chemical compounds, are capable of modulating plant development and physiology. These regulators exert notable effects by enhancing root proliferation, facilitating lignification, influencing plant architecture, and augmenting yield. Owing to their operational simplicity and relatively low cost, PGR applications hold substantial promise for cultivating seedlings with superior traits. In this study, four-year-old seedlings were employed to evaluate the impacts of three PGRs (paclobutrazol, chlormequat chloride, and diethyl aminoethyl hexanoate), alongside varied application methods (dosage and frequency), on the growth, physiological, and photosynthetic parameters of the seedlings. The findings revealed that treatment with 1.5 g/L paclobutrazol produced the most pronounced effects across a range of indicators. Specifically, this treatment markedly enhanced growth traits (e.g., branch diameter, new shoot length, lateral branch length, aboveground fresh and dry weights, root fresh and dry weights, lateral root dry weight, and number of second-order roots), physiological attributes (e.g., increased superoxide dismutase and peroxidase activities, elevated lignin content, and reduced relative conductivity and malondialdehyde levels), and photosynthetic metrics (e.g., elevated net photosynthetic rate, stomatal conductance, transpiration rate, and maximum net photosynthetic rate), thereby constituting the optimal treatment combination.