To improve the ecological and economic benefits of Korean pine (Pinus koraiensis), we analysed and evaluated its germplasm resources. This promotes in-depth research and utilisation of germplasm resources, providing excellent genetic resources for Korean pine breeding. We performed genetic analysis based on morphological and physiological traits and nuclear SSR molecular marker data was performed by collecting 314 clones (5 ramets of each clone) of Korean pine from eight (8) locations within the Korean pine range. The core collection underwent testing and evaluation for representativeness using variable rate (VR), coincidence rate (CR), variance difference percentage (VD), mean difference percentage (MD), Shannon index (I), and other indicators. The results indicated significant differences in morphological and physiological traits among the populations. All traits had a coefficient of variation (CV) greater than 10%, except for the water content of the needles (WC), which had an average CV of 17.636%. The populations showed high overall genetic diversity, with the HL (Helong) population exhibiting the highest genetic diversity, with an Ne (number of effective alleles), I, and He (expected heterozygosity) of 3.171, 1.103, and 0.528, respectively. Genetic variation mainly originated from individuals within populations, while the variation between populations was relatively small, at only 3%. The population did not exhibit any distinct subpopulation structures and was mainly derived from two admixed gene pools. Six core sets were obtained using different sampling strategies, and subset 6 was identified as the core collection, consisting of 114 individuals, representing a selection rate of 36.31%. In conclusion, the most appropriate method for constructing the core collection of Korean pines is the M-strategy (maximizing the number of alleles), based on both phenotypic and molecular data. The resulting core collection effectively represents the genetic diversity of the entire population effectively.

AP2/ERF is an important transcription factor family involved in physiological processes such as plant development and hormone signaling. In this study, based on the available transcriptome data of hybrid larch during floral induction, 13 DREB genes belonging to the AP2/EREBP family with complete CDS regions were identified through alignment using the NCBI website. We conducted a bioinformatics analysis on the gene sequences, examining their tissue specificity, response to hormone treatment, and response to environmental factors. The DREB genes in hybrid larch (Larix kaempferi × Larix olgensis) showed tissue-specific expression, with DREB7, DREB8, DREB10, DREB12, and DREB13 exhibiting higher expression levels in nascent buds and higher expression in female cones compared to male cones. They also showed high expression during signal convergence and floral induction, and were highly expressed in materials with good fertility, suggesting their positive role in the cone-setting process of hybrid larch. Additionally, 13 DREB genes were all induced by abscisic acid (ABA), gibberellin 3 (GA₃), and indoleacetic acid (IAA), with the most pronounced expression changes observed after ABA treatment, indicating that these genes might be mainly regulated by ABA. In response to temperature and photoperiod treatments, DREB7, DREB8, DREB10, DREB12, and DREB13 showed significant responses, with increased expression levels induced by low temperature, while no clear pattern was observed after long or short-day treatments. These results of the study provide a reference for understanding the function of the DREB gene family in hybrid larch, offer a theoretical basis for inducing floral bud differentiation in hybrid larch, and contribute to a better understanding of the molecular mechanisms underlying cone-setting in hybrid larch.

Korean pine (Pinus koraiensis Siebold & Zucc.) is an important timber and economic tree species in northeast China. Its seeds serve as both a primary means of propagation and a significant economic product. In this study, we identified 12 full-length MADS-box genes based on the Korean pine flower-induced transcriptome data available in our laboratory. These genes were identified through multiple sequence alignment and screening for conserved structural domains. We analyzed the genetic relationships of these genes and predicted their physicochemical properties. Additionally, we examined the expression patterns of three SHORT VEGETATIVE PHASE (SVP) genes across different tissues and developmental stages of Korean pine. The results indicate that the amino acid composition, molecular weight, isoelectric point, and other physicochemical properties of the MADS-box gene family in Pinus koraiensis are generally similar, though some individual variations are observed. A total of 12 MADS-box family genes were identified from the Korean pine transcriptome, distributed across five subfamilies. Conserved motif analysis revealed that these genes share similar conserved sequences. Structural and physicochemical analyses showed that genes with similar sequences exhibited comparable characteristics. Expression levels of the SVP genes varied significantly across different developmental stages and tissues, with the expression of the three SVP genes in leaves being markedly higher than in buds (approximately 200-fold). The expression levels of these genes in leaves were not only higher than in buds but also exceeded those in other tissues. Based on these findings, we conclude that these three SVP genes primarily play a suppressive role in the process of flower bud formation, helping Korean pine maintain a juvenile state under certain conditions, and are also involved in the growth and development of its leaves. This research provides a basis for future studies on the flowering induction mechanism in Korean pine.

With the intensification of global climate change and the frequent occurrence of extreme drought events, forest production is facing severe challenges. This study imposed drought stress and exogenous abscisic acid (ABA) treatment on Larix gmelini seedlings, evaluated their physiological characteristics, and analyzed the transcriptional response mechanism using transcriptome sequencing. The results showed that drought stress induced organ-specific changes in superoxide dismutase (SOD) and peroxidase (POD) activities, malondialdehyde (MDA) accumulation, and soluble protein content. SOD activity in leaves significantly increased, while POD activity, MDA content, and soluble protein levels in roots exhibited more dynamic changes. After ABA application, SOD activity in leaves reached its peak at 24 h, which was opposite to the situation in roots and stems, where POD activity was highest at 24 h. At 48 h, MDA accumulation was most significant in roots, while the early response in leaves was minimal. At 24 h, the soluble protein increase was most significant in stems. In addition, at this time point, ABA application significantly increased the soluble protein content in all three organs. Transcriptome sequencing analysis further identified core response genes involved in the MAPK signaling pathway, plant hormone signal transduction, starch and sucrose metabolism, and flavonoid biosynthesis pathways, including SNRK2, MAPKKK17, PYL, PP2C, XRN4, TMEM, TIR1, and TGA. In summary, Larix gmelini seedlings alleviate the inhibitory effect of drought stress on growth through a synergistic mechanism, specifically by activating the antioxidant system, initiating the MAPK signaling pathway, regulating plant hormone signal transduction, and reshaping carbon metabolism pathways, thereby enhancing stress resistance.