Morphological and Biochemical Responses of Pinus radiata Embryogenic Cultures to Elicitors, Salinity and Heat Stress

Pinus radiata is a commercially valuable forest species whose productivity is increasingly threatened by climate change-related biotic and abiotic stresses, such as diseases, soil salinization, and rising temperatures. Using a sufficiently optimized somatic embryogenesis protocol for radiata pine as a starting point, this study aimed to evaluate the morphological and biochemical responses of embryogenic cell lines subjected to different elicitors, such as methyl jasmonate and tagatose, during proliferation, or to sodium butyrate at the maturation stage. The effect of various stresses, such as salinity and high temperatures, was evaluated at the proliferation and germination stages. Biochemical analyses, including measurements of total protein, hydrogen peroxide, and malondialdehyde contents were carried out in embryogenic tissues and somatic plants, and growth was also evaluated in these tissues and plants. This growth assessment led to the classification of plants according to their suitability for ex vitro planting. Several embryogenic cell lines were tested, and the response to elicitation or stress was found to be highly genotype-dependent; however, some trends were observed, particularly in terms of growth. These results suggest that somatic embryogenesis combined with stress priming or elicitor application may be a viable strategy for improving biotic and abiotic stress response in radiata pine.