Influence of Physico-Chemical Factors on the Efficiency and Metabolite Profile of Adult Pinus radiata D. Don Bud Organogenesis

Genetic improvement programs for conifer forest species face the challenge of propagating elite individuals with superior characteristics in the present landscape of climate change; the problem is focused on the fact that when these individuals have shown the desirable traits, they have changed phase and therefore have lost the ability to be propagated by traditional methods. Based on our previous works on Pinus spp. regeneration of adult trees through organogenesis and trying to improve the protocol in Pinus radiata, our objective was to analyze the influence of collection dates and different 6-benzyladenine (BA) concentrations in the first phase of shoot induction, as well as the effect of different light types on the success of root induction. Moreover, we were interested in studying the effect of the abovementioned physico-chemical factors on the amino acid and carbohydrate content in the shoots developed in vitro. Reinvigorated shoots were obtained in both BA concentrations (22 or 44 mu M), although the highest BA concentration showed the best results in terms of shoot induction (explants forming shoots (46%) and number of shoots per explant (1.95 +/- 0.52)) when using initial explants collected in the first week of February. The percentage of explants forming shoots (EFS) was genotype-dependent. Explants from genotype A induced with the highest BA concentration showed the highest EFS (91%). With respect to the light treatment applied, significant differences in root induction (20%) and in the number of roots per explant (4.62 +/- 0.65) were observed in shoots cultured under white FL. Finally, significant differences in different phases of the rooting process were detected in the amounts of fructose, glucose and sucrose and in the content of threonine and tyrosine.