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

Abstract

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 μM), 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.

Testing Explant Sources, Culture Media, and Light Conditions for the Improvement of Organogenesis in Pinus ponderosa (P. Lawson and C. Lawson)

“…Contrary to our results, in P. radiata , in vitro shoots growing under FL showed high NR/E [ 42 ]. Regarding LLR, shoots under white LEDs and FL light showed longer primary roots.…”

“…In our experiments, BA at the concentrations tested (4.4, 22, and 44 µM) showed efficient organogenic response for NS, and, although not significant, a slightly higher response in whole zygotic embryos cultured in HLP supplemented with 22 µM BA was observed. A similar tendency was observed in several micropropagation protocols in Pinus where the culture medium was supplemented with BA (from 1 to 50 µM) to obtain bud induction [ 19 , 27 , 39 , 40 , 41 , 42 ].…”

“…A similar pattern was reported in Handroanthus ochraceus where plants showed higher root length values when exposed to low FL irradiances [ 12 ]. In contrast, longer roots were obtained in plants of P. radiata and Vitis ficifolia growing under red LEDs [ 42 , 57 ].…”

Adult Trees Cryptomeria japonica (Thunb. ex L.f.) D. Don Micropropagation: Factors Involved in the Success of the Process

“…In Pinus pseudostrobus shoots exposed to red LEDs, the best rooting rates were observed at 30 days of evaluation [26]. Contrary to our results, P. radiata and P. ponderosa shoots grown under white fluorescent light and white LEDs, respectively, displayed the highest rooting responses [43,47]. Regarding LLR, shoots under fluorescent light showed longer primary roots.…”

“…During Experiment 2, explants cultured with BA or m-T showed an efficient organogenic response regarding shoot induction percentage, and although not significant, a slightly higher response in BT explants induced with BA was observed. Analogous results were obtained in several organogenesis protocols from adult trees of Pinus pinea, P. radiata, Sequoia sempervirens, and P. halepensis, where, to obtain an in vitro shoot response, BA at concentrations ranging from 4.4 to 50 µM was utilized [10,[40][41][42][43].…”