Multi-strategy approach towards optimization of maturation and germination in radiata pine somatic embryogenesis

Abstract

Somatic embryogenesis is a powerful technique for forestry improvement programs when implementing multi-varietal forestry. However, it still faces some bottlenecks to be efficient in many forestry species. In this work we have studied the effect of some physico-chemical modifications at proliferation, maturation and germination stages of Pinus radiata D. Don somatic embryogenesis, as well as the impact of this modifications on plant conversion, survival, and on the morphology and biochemical profile (carbohydrate and amino acid analysis) of the resulting plantlets. Given the long culture period needed for maturation and germination in radiata pine, an increase of the plant yield could be very beneficial for its commercial application. Following these premises and based on the experiments performed, a preculture of 14 days without plant growth regulators before maturation seems to be beneficial for the development and germination of somatic embryos. Before germination, a cold storage at 4 °C had no detrimental effect and even increased plant conversion in some embryogenic cell lines (85% of germination and 64.6% of planted explants). During germination, supplementation of the culture medium with glutamine and a reduction of the sucrose content had a significant effect on germination (88%) and doubled the percentage of planted explants. Similarly, germinants were demonstrated to be influenced by the light source: fluorescent light enhanced root formation, whereas blue LED light increased the shoot height of somatic plants. Moreover, the highest plants showed lower contents of arginine, asparagine and total carbohydrates. Modification of the physico-chemical environment before or during somatic embryo maturation and germination improves the success of the process.