Evaluation of Cultivation Conditions and Genotype of Explants for Pinus sylvestris L. Somatic Embryogenesis in Karelian Plant Communities

The effect of 1/2 LV, MSG, DCR-based nutrient media with different content of 2.4-D, BA and carbohydrate sources (maltose, sucrose) on the response of Pinus sylvestris L. megagametophytes containing immature embryos was studied. Plant material was collected from 10–40-year-old trees growing in Petrozavodsk seed orchard, progeny trial, and city park. A total number of 3260 and 1860 megagametophytes were cultivated in vitro in 2022 and 2023, respectively. Most frequently embryonal-suspensor mass formation occurred from explants collected from plus trees’ clones at Petrozavodsk seed orchard and did not exceed 0.3%. The study identified a donor-tree genotype (864-2) whose explants, collected in different years, formed embryogenic cell masses proliferating for 9–10 months. It has been recommended to use the MSG nutrient medium for the successful embryonal-suspensor mass initiation. Prolonged embryonal-suspensor mass cultivation on the medium with high phytohormone content led to its degradation and required subculturing on the substrate with lower auxin and cytokinin content. In this study, we have induced the process of Pinus sylvestris somatic embryos maturation up to the clearly visible globular stage.